methylnaltrexone and Constipation

Preclinical and clinical studies suggest that activation of the µ-opioid receptor may reduce overall survival and increase the risk for all-cause mortality in patients with cancer and noncancer pain. Methylnaltrexone, a selective, peripherally acting µ-opioid receptor antagonist, has demonstrated efficacy for the treatment of opioid-induced constipation. This retrospective analysis of 12 randomized, double-blind, placebo-controlled studies of methylnaltrexone evaluated the treatment of opioid-induced bowel disorders in patients with advanced illness or noncancer pain.. The risk of all-cause mortality within 30 days after the last dose of study medication during the double-blind phase was compared between methylnaltrexone and placebo groups. The data were further stratified by cancer vs noncancer, age, gender, and acute vs chronic diagnoses.. Pooled data included 2,526 methylnaltrexone-treated patients of which 33 died, and 1,192 placebo-treated patients of which 35 died. The mortality rate was 17.8 deaths/100 person-years of exposure in the methylnaltrexone group and 49.5 deaths/100 person-years of exposure for the placebo group. The all-cause mortality risk was significantly lower among patients receiving methylnaltrexone compared with placebo (hazard ratio: 0.399, 95% confidence interval: 0.25, 0.64; P = .0002), corresponding to a 60% risk reduction. Significant risk reductions were observed for those receiving methylnaltrexone who had cancer or chronic diagnoses. Methylnaltrexone-treated patients had a significantly reduced mortality risk compared with placebo regardless of age or gender.. Methylnaltrexone reduced all-cause mortality vs placebo treatment across multiple trials, suggesting methylnaltrexone may confer survival benefits in patients with opioid-induced bowel disorders taking opioids for cancer-related or chronic noncancer pain.

Topics: Analgesics, Opioid; Chronic Pain; Constipation; Double-Blind Method; Humans; Naltrexone; Narcotic Antagonists; Randomized Controlled Trials as Topic; Retrospective Studies

Opioid-induced constipation (OIC) is a frequent consequence of opioid analgesia that may increase patient risk for emergency department visits and hospitalization. Methylnaltrexone is a peripherally acting µ-opioid receptor antagonist indicated for the treatment of OIC.. To assess the safety and efficacy of a single methylnaltrexone dose.. Results were pooled from three randomized, placebo-controlled methylnaltrexone (MNTX) studies in opioid-treated patients with advanced illness and OIC, despite treatment with conventional laxatives. Baseline assessments included demographics, disease/treatment characteristics, and functional levels. Efficacy endpoints included rescue-free laxation (RFL) rates within 4 and 24 h, time to first RFL, pain score change, and adverse events (AEs) after a single MNTX dose or placebo.. The analysis included 281 patients receiving MNTX and 237 receiving placebo. Mean age was 66.2 years for MNTX and 65.8 for placebo; ∼50% were men. The most frequent primary diagnosis was cancer (MNTX = 70.5%; placebo = 66.2%) and most (∼98%) were receiving at least one laxative at baseline. RFL occurred in 61.4% vs. 16.0%, and 72.1% vs. 40.1% MNTX vs. placebo patients, within 4 and 24 h of the initial dose, respectively. Relative to placebo, MNTX use reduced the time to first RFL, with most MNTX-treated patients achieving RFL within 2 h. Baseline and posttreatment pain scores were similar (p = 0.9556 vs. placebo for current and worst pain change from baseline), demonstrating that MNTX did not negatively affect opioid analgesia. Most AEs were gastrointestinal related and dissipated by the second dose.. Methylnaltrexone provides early RFL without compromising analgesia in patients receiving chronic opioid therapy.

Topics: Aged; Analgesics, Opioid; Constipation; Humans; Male; Naltrexone; Opioid-Induced Constipation; Quaternary Ammonium Compounds

To summarize and evaluate the existing literature regarding medications to treat opioid-induced constipation (OIC) in patients with chronic noncancer pain (CNCP).. PubMed, EMBASE, and Web of Science were searched using the following terms: constipation, opioid, chronic, pain, noncancer, nonmalignant, methylnaltrexone, alvimopan, lubiprostone, naloxegol, and naldemedine.. The search was limited to randomized controlled trials reporting human outcomes. Data extracted included the following: study design, population, intervention, control, outcomes related to OIC and safety, and potential biases assessed using Cochrane Collaboration's Risk of Bias Assessment Tool.. After assessment, 16 of the 190 studies were included: methylnaltrexone (n = 4), naloxegol (n = 3), naldemedine (n = 2), lubiprostone (n = 3), and alvimopan (n = 4). Lubiprostone was the only nonperipherally acting µ-opioid receptor antagonist included. Only 1 study (naloxegol) used "usual care" (nonstudy laxative) rather than placebo as a comparator. Placebo-controlled trials demonstrated benefit for methylnaltrexone, naloxegol, naldemedine, and lubiprostone, with conflicting evidence for alvimopan. No data suggest that one agent is better than another. Overall risk of bias across all studies was low to moderate.. With risk of bias determined to be low to moderate, published data to date suggest that methylnaltrexone, naloxegol, and naldemedine may be appropriate to treat OIC in patients with CNCP.

Topics: Analgesics, Opioid; Chronic Pain; Constipation; Evidence-Based Practice; Humans; Laxatives; Lubiprostone; Morphinans; Naltrexone; Narcotic Antagonists; Piperidines; Polyethylene Glycols; Quaternary Ammonium Compounds; Randomized Controlled Trials as Topic

Topics: Analgesics, Opioid; Cancer Pain; Constipation; Enema; Gastrointestinal Agents; Gastrostomy; Humans; Laxatives; Morphinans; Naltrexone; Piperidines; Polyethylene Glycols; Practice Guidelines as Topic; Quaternary Ammonium Compounds

Opioid-induced bowel dysfunction (OIBD) is characterised by constipation, incomplete evacuation, bloating, and gastric reflux. It is one of the major adverse events of treatment for pain in cancer and in palliative care, resulting in increased morbidity and reduced quality of life.This is an update of two Cochrane reviews. One was published in 2011, Issue 1 on laxatives and methylnaltrexone for the management of constipation in people receiving palliative care; this was updated in 2015 and excluded methylnaltrexone. The other was published in 2008, Issue 4 on mu-opioid antagonists (MOA) for OIBD. In this updated review, we only included trials on MOA (including methylnaltrexone) for OIBD in people with cancer and people receiving palliative care.. To assess the effectiveness and safety of MOA for OIBD in people with cancer and people receiving palliative care.. We searched the Cochrane Central Register of Controlled Trials, MEDLINE, Embase, CINAHL, and Web of Science to August 2017. We also searched clinical trial registries and regulatory websites. We contacted manufacturers of MOA to identify further data.. We included randomised controlled trials (RCTs) that assessed the effectiveness and safety of MOA for OIBD in people with cancer and people at a palliative stage irrespective of the type of terminal disease they experienced.. Two review authors assessed risk of bias and extracted data. The appropriateness of combining data from the trials depended upon sufficient homogeneity across the trials. Our primary outcomes were laxation, impact on pain relief, and adverse events. Impact on pain relief was a primary outcome because a possible adverse effect of MOAs is a reduction in pain relief from opioids. We assessed the evidence on these outcomes using GRADE.. We identified four new trials for this update, bringing the total number included in this review to eight. In total, 1022 men and women with cancer irrespective of stage or at a palliative care stage of any disease were randomised across the trials. The MOAs evaluated were oral naldemedine and naloxone (alone or in combination with oxycodone), and subcutaneous methylnaltrexone. The trials compared with MOA with a placebo or with the active intervention administered at different doses or in combination with other drugs. The trial of naldemedine and the two of naloxone in combination with oxycodone were in people with cancer irrespective of disease stage. The trial on naloxone alone was in people with advanced cancer. The four trials on methylnaltrexone were undertaken in palliative care where most participants had cancer. All trials were vulnerable to biases; four were at a high risk as they involved a sample of fewer than 50 participants per arm.In the trial of naldemedine compared to placebo in 225 participants, there were more spontaneous laxations over the two-week treatment for the intervention group (risk ratio (RR) 1.93, 95% confidence intervals (CI) 1.36 to 2.74; moderate-quality evidence). In comparison with higher doses, lower doses resulted in fewer spontaneous laxations (0.1 mg versus 0.2 mg: RR 0.73, 95% CI 0.55 to 0.95; 0.1 mg versus 0.4 mg: RR 0.69, 95% CI 0.53 to 0.89; moderate-quality evidence). There was moderate-quality evidence that naldemedine had no effect on opiate withdrawal. There were five serious adverse events. All were in people taking naldemedine (low-quality evidence). There was an increase in the occurrence of other (non-serious) adverse events in the naldemedine groups (RR 1.36, 95% CI 1.04 to 1.79, moderate-quality evidence). The most common adverse event was diarrhoea.The trials on naloxone taken either on its own, or in combination with oxycodone (an opioid) compared to oxycodone only did not evaluate laxation response over the first two weeks of administration. There was very low-quality evidence that naloxone alone, and moderate-quality evidence that oxycodone/naloxone, had no effect on analgesia. There was low-quality evidence that oxycodone/naloxone did not increase the risk of serious adverse events and moderate-quality evidence that it did not increase risk of adverse events.In combined analysis of two trials of 287 participants, we found methylnaltrexone compared to placebo induced more laxations within 24 hours (. In this update, the conclusions for naldemedine are new. There is moderate-quality evidence to suggest that, taken orally, naldemedine improves bowel function over two weeks in people with cancer and OIBD but increases the risk of adverse events. The conclusions on naloxone and methylnaltrexone have not changed. The trials on naloxone did not assess laxation at 24 hours or over two weeks. There is moderate-quality evidence that methylnaltrexone improves bowel function in people receiving palliative care in the short term and over two weeks, and low-quality evidence that it does not increase adverse events. There is a need for more trials including more evaluation of adverse events. None of the current trials evaluated effects in children.

Topics: Constipation; Defecation; Female; Gastrointestinal Agents; Humans; Intestinal Diseases; Male; Nalbuphine; Naloxone; Naltrexone; Narcotic Antagonists; Neoplasms; Opioid-Related Disorders; Oxycodone; Palliative Care; Piperidines; Quaternary Ammonium Compounds; Randomized Controlled Trials as Topic; Receptors, Opioid, mu

The extensive and alarming use of opioids for pain management in patients with chronic pain receiving palliative care is associated with non-tolerable gastrointestinal (GI) adverse effects. Opioid-induced constipation (OIC) is the most common adverse effect impairing patient quality of life (QOL). In addition, OIC is one of the treatment limiting consequences of opioid analgesics. Management of OIC is becoming a challenge since traditional laxatives have limited efficiency. Peripherally acting mu-opioid receptor antagonists (PAMORA) have been developed for the treatment of OIC with methylnaltrexone bromide being the first approved to treat OIC in adults with advanced illness undergoing palliative care. Areas covered: The authors systematically review the clinical evidence for methylnaltrexone bromide including a review of the pharmacokinetic and pharmacodynamic data along with clinical effectiveness and cost-effectiveness. Though there is a need for further long-term clinical investigation, there is a large body of evidence for both its efficacy and safety in the treatment of OIC. Expert opinion: Methylnaltrexone has both subcutaneous injection and oral dosage forms available in the market. The lack of more evidence in specific populations such as pregnant women, pediatrics and elderly still remains. The global consumption of methylnaltrexone shows a projection of increased use since its approval worldwide in 2008.

Topics: Analgesics, Opioid; Chronic Pain; Clinical Trials as Topic; Constipation; Government Regulation; Half-Life; Humans; Naltrexone; Quality of Life; Quaternary Ammonium Compounds; Treatment Outcome

Opioids have been used for centuries, mostly as a sedative and to treat pain. Currently, they are used on a global scale for the treatment of acute and chronic pain in diseases as osteoarthritis, fibromyalgia, and low back pain. Binding of opioids on opioid receptors can cause a range of different effects such as changes in stress response, analgesia, motor activity and autonomic functions. This review provide a synthetic summary of the most recent literature on the use of drugs acting on mu-receptors to treat two prevalent functional bowel disorders, presenting with opposite bowel habit. Eluxadoline and naloxegol, methylnaltrexone and naldemedine are recently FDA and/or EMA approved drugs demonstrated to be effective and safe for treatment respectively of irritable bowel syndrome subtype diarrhea and opioid induced constipation.

Topics: Analgesics, Opioid; Animals; Antidiarrheals; Constipation; Defecation; Diarrhea; Gastrointestinal Motility; Gastrointestinal Tract; Humans; Imidazoles; Inflammatory Bowel Diseases; Laxatives; Morphinans; Naltrexone; Narcotic Antagonists; Phenylalanine; Polyethylene Glycols; Quaternary Ammonium Compounds; Receptors, Opioid, mu; Signal Transduction

More than 6 million people in Germany suffer from chronic pain which greatly impairs their wellbeing. Often the only therapeutic option is to use class 2 or 3 analgesic opioids in the WHO classification, as class 1 analgesics may be toxic or of limited efficacy. However, the high incidence of opioid side effects leads to high discontinuation rates. Thus, the success of opioid treatment is also highly dependent on the management of the safety and tolerability of the treatment. Most opioid side effects, such as nausea and sedation, predominantly occur in the initial phase of therapy. In contrast, opioid-induced constipation can last throughout opioid therapy. First-line treatment with laxatives does not solve the problem in all patients. Possible second-line therapies include opioid receptor antagonists, such as Naloxone, oral-administered Naloxegol, or subcutaneously given Methylnaltrexone. The discussion also covers the management of other common side effects of opioids, such as nausea, vomiting, sedation, pruritus, micturition disorder, and further symptoms.

Topics: Administration, Cutaneous; Administration, Oral; Analgesics, Opioid; Chronic Pain; Constipation; Drug-Related Side Effects and Adverse Reactions; Germany; Humans; Morphinans; Naltrexone; Narcotic Antagonists; Polyethylene Glycols; Quaternary Ammonium Compounds; Treatment Outcome

Opioid-related bowel dysfunction is a common and potentially severe adverse effect from treatment with opioid analgesics. Its development is not dose related, nor do patients develop tolerance. Opioid-induced constipation (OIC) can lead to fecal impaction, bowel obstruction, and bowel perforation as well as noncompliance with opioid analgesics and poor quality of life. Routine administration of laxatives is necessary to maintain bowel function, and, in refractory cases, other modalities must be pursued. Available options are limited but include peripherally acting μ-opioid receptor antagonists (PAMORAs), including methylnaltrexone. Naloxegol is a newly developed PAMORA that is available through the oral route. At the therapeutic dose of 25 mg daily, naloxegol is effective and safe, with a limited side effect profile and is associated with preservation of centrally mediated analgesia. In this article, we discuss the pharmacokinetics, pharmacodynamics, adverse effects, clinical trials, and cost considerations of naloxegol. Finally, we discuss its potential role as a novel key treatment for OIC in palliative medicine patients.

Topics: Analgesics, Opioid; Constipation; Drug Interactions; Humans; Morphinans; Naltrexone; Narcotic Antagonists; Pain; Polyethylene Glycols; Quality of Life; Quaternary Ammonium Compounds; Randomized Controlled Trials as Topic

Opioid-based management of noncancer pain has become much more prevalent over the last 2 decades and is responsible for a wide range of side-effects, particularly affecting the intestinal tract causing opioid-induced constipation (OIC). This review will consider results of recent clinical trials that have provided evidence of new pharmacological management options for the treatment of OIC.. Supportive use of conventional agents, such as stool softeners, osmotic laxatives, and stimulating laxatives in OIC has limited efficacy. The peripheral μ-opioid receptor antagonist (PAMORA) methylnaltrexone (MNTX) was first FDA approved for OIC in patients with advanced illness and later also for OIC in noncancer pain patients; clinical trial results indicated MNTX did not reverse opioid analgesia and did not trigger central opioid withdrawal. Another PAMORA, the orally available naloxegol, has also gained recent FDA approval for the treatment of OIC in adults with chronic, noncancer pain. Lubiprostone, a bicyclical fatty acid acting via activation of intestinal chloride channel-2 (ClC-2), was also approved for OIC treatment in patients with noncancer pain.. PAMORA MNTX and naloxegol and the intestinal chloride channel-2 (ClC-2) activator lubiprostone represent additional possible therapeutic options for the management of OIC in patients with chronic noncancer pain.

Topics: Analgesics, Opioid; Chloride Channel Agonists; Chronic Pain; Constipation; Humans; Lubiprostone; Morphinans; Naltrexone; Narcotic Antagonists; Polyethylene Glycols; Quaternary Ammonium Compounds; Receptors, Opioid, mu

Constipation is a common adverse effect in patients requiring long-term opioid therapy for pain control. Methylnaltrexone, a quaternary peripheral mu-opioid receptor antagonist, is an effective treatment of opioid induced constipation (OIC) without affecting centrally mediated analgesia. Our objective was to conduct a review and meta-analysis to evaluate the efficacy of methylnaltrexone for treatment of OIC, as well as to provide a clinical discussion regarding newly developed alternatives and provide the current treatment algorithm utilized at our institution.. We performed a systematic review and meta-analysis of randomized control trials using Cochrane Collaboration Databases and MEDLINE from 2007-present. Literature related to methylnaltrexone, opioids, opioid receptors, opioid antagonists, opioid-induced constipation were reviewed. A meta-analysis was completed with the primary outcome of rescue-free bowel movement (RFBM) within four hours of administration. All pooled analyses were based on random-effects models.. 1239 patients were analyzed; 599 received methylnaltrexone and 640 received placebo. With a 95% CI calculated, the true risk difference is between 0.267 and 0.385, demonstrating a statistically significant difference in RFBM between treatment and placebo groups (p < 0.0001). Both the 0.15 mg/kg, 0.30 mg/kg doses every other day, and 12 mg/day dose were found to have increased risk of RFBM compared to placebo.. Results support the use of methylnaltrexone. Furthermore, the use of methylnaltrexone to induce laxation may decrease use of health care resources, increase work productivity, and improve cost utilization. New treatments have been made available; however, controlled clinical studies are needed to demonstrate long-term efficacy, safety and cost-effectiveness. Possible limitations of this study include the relatively small number of randomized, placebo-controlled trials investigating the efficacy of methylnaltrexone versus placebo. There is also the possibility of publication bias, which may lead to overestimating the efficacy of methylnaltrexone in treating OIC.

Topics: Analgesics, Opioid; Chronic Pain; Constipation; Humans; Naltrexone; Narcotic Antagonists; Quaternary Ammonium Compounds; Receptors, Opioid, mu; Treatment Outcome

Constipation is a common and often debilitating condition in the elderly, which may be caused by underlying disease conditions, structural abnormalities in the bowel, and a variety of medications such as anticholinergics, antidepressants, and opiates. In this review, we focus on opioid-induced constipation (OIC), which is often underrecognized and undertreated in the elderly. When opioid therapy is initiated, healthcare providers are encouraged to evaluate risk factors for the development of constipation as part of a thorough patient history. To this end, the patient assessment should include the use of validated instruments, such as the Bristol Stool Scale and Bowel Function Index, to confirm the diagnosis and provide a basis for evaluating treatment outcomes. Healthcare providers should use a stepwise approach to the treatment of OIC in the elderly. Conventional laxatives are a first-line option and considered well tolerated with short-term use as needed; however, evidence is lacking to support their effectiveness in OIC. Moreover, because of the risk of adverse events and other considerations, such as chewing difficulties and swallowing disorders, conventional oral laxatives may be inappropriate for the treatment of OIC in the elderly. Thus, the availability of new pharmacologic agents such as the peripherally acting µ-opioid receptor antagonists methylnaltrexone and naloxegol, which target the underlying causes of OIC, and the secretagogue lubiprostone may provide more effective treatment options for elderly patients with OIC.

Topics: Aged; Analgesics, Opioid; Constipation; Health Personnel; Humans; Laxatives; Naltrexone; Narcotic Antagonists; Pain; Quaternary Ammonium Compounds; Receptors, Opioid, mu; Treatment Outcome

This article describes the second update of a Cochrane review on the effectiveness of laxatives for the management of constipation in people receiving palliative care. Previous versions were published in 2006 and 2010 where we also evaluated trials of methylnaltrexone; these trials have been removed as they are included in another review in press. In these earlier versions, we drew no conclusions on individual effectiveness of different laxatives because of the limited number of evaluations. This is despite constipation being common in palliative care, generating considerable suffering due to the unpleasant physical symptoms and the availability of a wide range of laxatives with known differences in effect in other populations.. To determine the effectiveness and differential efficacy of laxatives used to manage constipation in people receiving palliative care.. We searched the Cochrane Central Register of Controlled Trials (CENTRAL; The Cochrane Library), MEDLINE, EMBASE, CINAHL and Web of Science (SCI & CPCI-S) for trials to September 2014.. Randomised controlled trials (RCTs) evaluating laxatives for constipation in people receiving palliative care.. Two authors assessed trial quality and extracted data. The appropriateness of combining data from the studies depended upon clinical and outcome measure homogeneity.. We identified five studies involving the laxatives lactulose, senna, co-danthramer, misrakasneham, docusate and magnesium hydroxide with liquid paraffin. Overall, the study findings were at an unclear risk of bias. As all five studies compared different laxatives or combinations of laxatives, it was not possible to perform a meta-analysis. There was no evidence on whether individual laxatives were more effective than others or caused fewer adverse effects.. This second update found that laxatives were of similar effectiveness but the evidence remains limited due to insufficient data from a few small RCTs. None of the studies evaluated polyethylene glycol or any intervention given rectally. There is a need for more trials to evaluate the effectiveness of laxatives in palliative care populations. Extrapolating findings on the effectiveness of laxatives evaluated in other populations should proceed with caution. This is because of the differences inherent in people receiving palliative care that may impact, in a likely negative way, on the effect of a laxative.

Topics: Analgesics, Opioid; Anthraquinones; Cathartics; Constipation; Humans; Lactulose; Magnesium Hydroxide; Naltrexone; Palliative Care; Paraffin; Quaternary Ammonium Compounds; Randomized Controlled Trials as Topic; Senna Extract

Constipation is a common adverse effect of opioids. As an example, constipation is reported in 52% of people with advanced malignancy, and this figure rises to 87% in people who are terminally ill and taking opioids. There is no reason to believe that people with chronic non-malignant disease who are prescribed opioids will be any less troubled by this adverse effect.. We conducted a systematic overview and aimed to answer the following clinical question: What are the effects of opioid antagonists for constipation in people prescribed opioids? The population we studied included people with any condition, although most studies were in people with cancer pain. We searched Medline, Embase, The Cochrane Library, and other important databases up to May 2014 (Clinical Evidence reviews are updated periodically; please check our website for the most up-to-date version of this review).. At this update, searching of electronic databases retrieved 162 studies. After deduplication and removal of conference abstracts, 84 records were screened for inclusion in the review. Appraisal of titles and abstracts led to the exclusion of 47 studies and the further review of 37 full publications. Of the 37 full articles evaluated, two systematic reviews and one RCT were included at this update. We performed a GRADE evaluation for three PICO combinations.. In this systematic overview we categorised the efficacy for three interventions based on information relating to the effectiveness of alvimopan, methylnaltrexone, and naloxone.

Topics: Analgesics, Opioid; Constipation; Gastrointestinal Agents; Humans; Naloxone; Naltrexone; Narcotic Antagonists; Piperidines; Quaternary Ammonium Compounds; Treatment Outcome

The prevalence of constipation in palliative care patients varies. There is uncertainty about the choice from varying recommendations for pharmacological management of constipation and a varying clinical practice in palliative care settings. The purpose of the review was to evaluate the current recommendations of therapy guidelines and to determine the effectiveness and safety of laxative administration for the management of constipation in palliative care patients.. Despite the clinical importance, there are limited data on the efficacy and safety of laxatives in palliative care patients. The social acceptability varies from country to country, but overall, oral laxatives should, where possible, be used in preference. Systemic opioid antagonists, such as naloxone and methylnaltrexone have been studied in few clinical trials. There is a paucity of well designed, prospective, randomized controlled trials with large enough numbers of patients suffering from constipation and treated with pharmacological methods.. There are limited data available on the conventional pharmacological treatment of constipation in palliative care patients due to insufficient randomized controlled trials. However, subcutaneously administered methylnaltrexone was found to be effective in aiding of laxation and well tolerated with limited or transient side effects in palliative care patients.

Topics: Analgesics, Opioid; Constipation; Humans; Injections, Subcutaneous; Laxatives; Naltrexone; Narcotic Antagonists; Palliative Care; Practice Guidelines as Topic; Quaternary Ammonium Compounds

There has been no definitive synthesis of the evidence for any benefit of available pharmacological therapies in opioid-induced constipation (OIC). We conducted a systematic review and meta-analysis to address this deficit.. We searched MEDLINE, EMBASE, EMBASE Classic, and the Cochrane central register of controlled trials through to December 2012 to identify placebo-controlled trials of μ-opioid receptor antagonists, prucalopride, lubiprostone, and linaclotide in the treatment of adults with OIC. No minimum duration of therapy was required. Trials had to report a dichotomous assessment of overall response to therapy, and data were pooled using a random effects model. Effect of pharmacological therapies was reported as relative risk (RR) of failure to respond to therapy, with 95% confidence intervals (CIs).. Fourteen eligible randomized controlled trials (RCTs) of μ-opioid receptor antagonists, containing 4,101 patients, were identified. These were superior to placebo for the treatment of OIC (RR of failure to respond to therapy=0.69; 95% CI 0.63-0.75). Methylnaltrexone (six RCTs, 1,610 patients, RR=0.66; 95% CI 0.54-0.84), naloxone (four trials, 798 patients, RR=0.64; 95% CI 0.56-0.72), and alvimopan (four RCTs, 1,693 patients, RR=0.71; 95% CI 0.65-0.78) were all superior to placebo. Total numbers of adverse events, diarrhea, and abdominal pain were significantly commoner when data from all RCTs were pooled. Reversal of analgesia did not occur more frequently with active therapy. Only one trial of prucalopride was identified, with a nonsignificant trend toward higher responder rates with active therapy. Two RCTs of lubiprostone were found, with significantly higher responder rates with lubiprostone in both, but reporting of data precluded meta-analysis.. μ-Opioid receptor antagonists are safe and effective for the treatment of OIC. More data are required before the role of prucalopride or lubiprostone in the treatment of OIC are clear.

Topics: Alprostadil; Analgesics, Opioid; Benzofurans; Constipation; Female; Gastrointestinal Agents; Humans; Lubiprostone; Male; Naloxone; Naltrexone; Narcotic Antagonists; Peptides; Piperidines; Quaternary Ammonium Compounds; Receptors, Opioid, mu

Topics: Analgesics, Opioid; Combined Modality Therapy; Constipation; Delayed-Action Preparations; Diet Therapy; Humans; Laxatives; Life Style; Naloxone; Naltrexone; Narcotic Antagonists; Piperidines; Quaternary Ammonium Compounds

Topics: Administration, Oral; Aged; Constipation; Dose-Response Relationship, Drug; Female; Humans; Injections, Subcutaneous; Laxatives; Male; Middle Aged; Naltrexone; Narcotic Antagonists; Palliative Care; Quaternary Ammonium Compounds; Randomized Controlled Trials as Topic

Most prescribed opioids exert their analgesic effects via activation of central μ-opioid receptors. However, μ-opioid receptors are also located in the gastrointestinal (GI) tract, and activation of these receptors by opioids can lead to GI-related adverse effects, in particular opioid-induced constipation (OIC). OIC has been associated with increased use of healthcare resources, increased healthcare costs, and decreased quality of life for patients. Nonpharmacologic (e.g., increased fiber uptake) and pharmacologic agents (e.g., laxatives) may be considered for the treatment and prevention of OIC. However, many interventions, such as laxatives alone, are generally insufficient to reverse OIC because they do not target the underlying cause of OIC, opioid activation of μ-opioid receptors in the GI tract. Therefore, there has been keen interest in antagonism of the μ-opioid receptor in the periphery to inhibit the effects of opioids in the GI tract. In this review, currently available pharmacologic therapies for the treatment and prevention of OIC are summarized briefly, with a primary focus on the administration of the peripheral μ-opioid receptor antagonist methylnaltrexone bromide in patients with OIC and advanced illness who are receiving palliative care. Also, clinical trial data of methylnaltrexone treatment in patients with OIC and other pain conditions (i.e., chronic noncancer pain and pain after orthopedic surgery) are reviewed. Data support that methylnaltrexone is efficacious for the treatment of OIC and has a favorable tolerability profile.

Topics: Analgesics, Opioid; Clinical Trials as Topic; Constipation; Dietary Fiber; Humans; Laxatives; Naltrexone; Narcotic Antagonists; Pain; Quaternary Ammonium Compounds; Receptors, Opioid, mu

Topics: Administration, Cutaneous; Administration, Oral; Analgesics, Opioid; Constipation; Drug Therapy, Combination; Gastrointestinal Motility; Humans; Laxatives; Naltrexone; Narcotic Antagonists; Oxycodone; Quaternary Ammonium Compounds

Symptoms associated with disorders of the motility of colon and rectum are common problems in clinical practice. Advances in this field continue to expand our understanding of these disorders and provide new and different treatments with promising results.. This article reviews new advances in the past year on the measurement and diagnosis of colonic transit. Recently published data question the importance of dietary fiber in the prevention of colonic diverticulosis and diverticulitis, and support the efficacy of a number of different therapies aimed at improving colonic motility and visceral sensation in constipation and reversing the effects of opioid induced constipation with peripherally acting opioid antagonists.. The articles referenced in this review help inform the reader on new developments in the diagnosis and management of patients with colonic and rectal motility disorders.

Topics: Constipation; Diet; Dipeptides; Diverticulosis, Colonic; Gastrointestinal Agents; Gastrointestinal Transit; Humans; Naltrexone; Narcotic Antagonists; Peptides; Piperidines; Quaternary Ammonium Compounds; Rectal Diseases; Thiazepines; Tryptophan Hydroxylase

Topics: Aged; Constipation; Evidence-Based Nursing; Humans; Laxatives; Middle Aged; Naltrexone; Palliative Care; Quaternary Ammonium Compounds; Randomized Controlled Trials as Topic

Opioids are one of the most widely used therapies for the palliative treatment of cancer pain; however, despite their proven analgesic efficacy, they are associated with several adverse effects. Associated with psychological distress and multiple concomitant clinical concerns, constipation is the most commonly occurring adverse effect of chronic opioid therapy in cancer patients. Whilst prophylaxis remains the first-line management option, methylnaltrexone is a recommended treatment option for opioid-related constipation if administration of laxatives is ineffective. Due to its inability to cross the blood-brain barrier, methylnaltrexone exerts a peripheral inhibition of opioid-related effects without influencing the opioid-induced central effects; as a result, the analgesic effect of opioids is unaffected. Moreover, multiple clinical trials, albeit not always conducted specifically in cancer patients, have demonstrated that up to 4 months' treatment with either intravenous or subcutaneous methylnaltrexone provides effective relief from opioid-related constipation and is well tolerated. Preliminary evidence indicates that the addition of methylnaltrexone to standard care for opioid-related constipation may also be advantageous from a pharmacoeconomic perspective. In addition, preliminary data suggest that methylnaltrexone could be associated with some further clinical benefits other than the treatment of opioid-related constipation, such as the improvement of gastric emptying, the relief of nausea/vomiting, and the reduction of the risk of regurgitation and pulmonary aspiration. This narrative review examines the most recent evidence and evaluates the current role of methylnaltrexone in the management of opioid-related constipation, and its potential efficacy in cancer patients. The pharmacokinetics, pharmacodynamics, efficacy and tolerability of methylnaltrexone are discussed.

Topics: Analgesics, Opioid; Constipation; Humans; Naltrexone; Narcotic Antagonists; Neoplasms; Pain; Palliative Care; Quaternary Ammonium Compounds

Opioids have become the gold standard for treatment of severe pain in advanced disease, but adverse effects can affect the quality of life. Opioid-induced bowel dysfunction can lead to refractory constipation. Methylnaltrexone bromide is a peripherally acting mu antagonist and is indicated for the treatment of opioid-induced constipation in patients with advanced illness, when response to standard laxative therapy has been inefficacious. This pharmacology update will review the etiology, pathophysiology, and treatment of opioid-induced constipation, focused on methylnaltrexone as a novel treatment for refractory cases.

Topics: Analgesics, Opioid; Constipation; Defecation; Humans; Naltrexone; Narcotic Antagonists; Pain, Intractable; Palliative Care; Quality of Life; Quaternary Ammonium Compounds

Opioid-induced constipation is a major side effect of the use of opioid pain medications in a palliative care population. At present, the only approved treatment for opioid-induced constipation is methylnaltrexone bromide subcutaneous injection. Methylnaltrexone is a peripherally restricted opioid antagonist with μ-opioid receptor selectivity that can reduce opioid activity in peripheral organs such as the gastrointestinal tract while sparing the pain relief afforded by the pain medications.. This article addresses the pharmacokinetics of parenterally administered methylnaltrexone, including the studies in humans that form the basis for our understanding, and information on the disposition, metabolism and elimination of the drug. From this review, the reader will gain an understanding of the body's handling of methylnaltrexone following intravenous or subcutaneous administration.. Studies conducted to date indicate that methylnaltrexone has high bioavailability after subcutaneous administration at therapeutic dose levels, a terminal half-life of ∼ 8 - 9 h, minimal metabolism, elimination involving renal and non-renal routes, and a limited potential for drug-drug interactions. Combined with high efficacy and good tolerability, the predictable pharmacokinetic behavior of methylnaltrexone facilitates its successful utilization in clinical practice for the treatment of opioid-induced constipation in patients with advanced medical illness.

Topics: Clinical Trials as Topic; Constipation; Humans; Injections, Intravenous; Injections, Subcutaneous; Naltrexone; Narcotic Antagonists; Palliative Care; Quaternary Ammonium Compounds

Constipation is common in palliative care; it can generate considerable suffering due to the unpleasant physical symptoms. In the first Cochrane Review on effectiveness of laxatives for the management of constipation in palliative care patients, published in 2006, no conclusions could be drawn because of the limited number of evaluations. This article describes the first update of this review.. To determine the effectiveness of laxatives or methylnaltrexone for the management of constipation in palliative care patients.. We searched databases including MEDLINE and CENTRAL (The Cochrane Library) in 2005 and in the update to August 2010.. Randomised controlled trials (RCTs) evaluating laxatives for constipation in palliative care patients. In the update we also included RCTs on subcutaneous methylnaltrexone; an opioid-receptor antagonist that is now licensed for the treatment of opioid-induced constipation in palliative care when response to usual laxative therapy is insufficient.. Two authors assessed trial quality and extracted data. The appropriateness of combining data from the studies depended upon clinical and outcome measure homogeneity.. We included seven studies involving 616 participants; all under-reported methodological features. In four studies the laxatives lactulose, senna, co-danthramer, misrakasneham, and magnesium hydroxide with liquid paraffin were evaluated. In three methylnaltrexone.In studies comparing the different laxatives evidence was inconclusive. Evidence on subcutaneous methylnaltrexone was clearer; in combined analysis (287 participants) methylnaltrexone, in comparison with a placebo, significantly induced laxation at 4 hours (odds ratio 6.95; 95% confidence interval 3.83 to 12.61). In combined analyses there was no difference in the proportion experiencing side effects, although participants on methylnaltrexone suffered more flatulence and dizziness. No evidence of opioid withdrawal was found. In one study severe adverse events, commonly abdominal pain, were reported that were possibly related to methylnaltrexone. A serious adverse event considered to be related to the methylnaltrexone also occurred; this involved a participant having severe diarrhoea, subsequent dehydration and cardiovascular collapse.. The 2010 update found evidence on laxatives for management of constipation remains limited due to insufficient RCTs. However, the conclusions of this update have changed since the original review publication in that it now includes evidence on methylnaltrexone. Here it found that subcutaneous methylnaltrexone is effective in inducing laxation in palliative care patients with opioid-induced constipation and where conventional laxatives have failed. However, the safety of this product is not fully evaluated. Large, rigorous, independent trials are needed.

Topics: Analgesics, Opioid; Anthraquinones; Cathartics; Constipation; Humans; Lactulose; Magnesium Hydroxide; Naltrexone; Palliative Care; Paraffin; Quaternary Ammonium Compounds; Randomized Controlled Trials as Topic; Senna Extract

Methylnaltrexone is a selective mu-opioid receptor antagonist that has restricted ability to cross the blood-brain barrier, thus enabling reversal of opioid-induced peripheral effects, such as constipation, without affecting the central effects, such as pain relief. Treatment with subcutaneous methylnaltrexone 0.15-0.30 mg/kg, relative to placebo, significantly increased the rescue-free laxation response rate within 4 hours of the first dose (primary endpoint) in adult patients with opioid-induced constipation and advanced illness in two randomized, double-blind, placebo-controlled, multicentre, phase III studies; one was a single-dose study (n = 154), the other a multiple-dose study (n = 133). In the multiple-dose study, rescue-free laxation response rates within 4 hours after at least two of the first four doses (coprimary endpoint) were also significantly higher in methylnaltrexone recipients than in placebo recipients. Moreover, median time to laxation after the first dose was significantly shorter in methylnaltrexone recipients than in placebo recipients in both studies. Methylnaltrexone was not associated with any significant changes in pain scores or central opioid withdrawal in these studies. Methylnaltrexone was generally well tolerated in clinical trials; most adverse events were of mild to moderate severity.

Topics: Analgesics, Opioid; Constipation; Humans; Molecular Structure; Naltrexone; Quaternary Ammonium Compounds; Randomized Controlled Trials as Topic; Receptors, Opioid, mu; Treatment Outcome

Opioid-induced constipation (OIC) is associated with negative impact of opioid analgesics on opioid receptors located in the gut wall. Until recently, OIC was treated symptomatically only, with different laxatives which did not target the pathophysiology of OIC. Recently, several opioid receptor antagonists have been introduced in the treatment of OIC. Methylnaltrexone (MNTX) is a peripheral mu-opioid receptor antagonist for subcutaneous administration, which does not evoke symptoms of opioid abstinence. MNTX is indicated for patients with OIC who are not amenable to therapy with oral laxatives. In clinical trials, the effectiveness of MNTX assessed as its ability to induce spontaneous bowel movement, is 50%-60% of treated patients; MNTX demonstrates significant superiority over placebo. Another product is combination of oral formulation of prolonged release oxycodone and prolonged release naloxone (PR oxycodone/PR naloxone), indicated for patients who require opioid administration for chronic pain and have already developed OIC, and for those who need opioid therapy and take the drug to prevent OIC. Naloxone administered orally displays local, antagonist effects on opioid receptors in the gut wall, negligible systemic bioavailability, and significantly reduces the oxycodone constipating effect. PR oxycodone/PR naloxone has similar analgesic efficacy, but causes less constipation and less laxative consumption in comparison with patients treated with oxycodone alone. Both products are expensive, therefore their administration should be carefully considered. On the other hand, uncontrolled OIC and the necessity to perform rectal invasive procedures (enema, manual evacuation) lead not only to increased health care costs, but most importantly, cause severe patient suffering.

Topics: Analgesics, Opioid; Clinical Trials as Topic; Constipation; Delayed-Action Preparations; Drug Combinations; Humans; Laxatives; Naloxone; Naltrexone; Narcotic Antagonists; Oxycodone; Quaternary Ammonium Compounds

Opium is arguably one of the oldest herbal medicines, being used as analgesic, sedative and antidiarrheal drug for thousands of years. These effects mirror the actions of the endogenous opioid system and are mediated by the principal mu-, kappa- and delta-opioid receptors. In the gut, met-enkephalin, leu-enkephalin, beta-endorphin and dynorphin occur in both neurons and endocrine cells. When released, opioid peptides activate opioid receptors on the enteric circuitry controlling motility and secretion. As a result, inhibition of gastric emptying, increase in sphincter tone, induction of stationary motor patterns and blockade of peristalsis ensue. Together with inhibition of ion and fluid secretion, these effects cause constipation, one of the most frequent and troublesome adverse reactions of opioid analgesic therapy. Although laxatives are most frequently used to ameliorate opioid-induced bowel dysfunction, their efficacy is unsatisfactory. Specific antagonism of peripheral opioid receptors is a more rational approach. This goal is addressed by the use of opioid receptor antagonists with limited absorption such as oral prolonged-release naloxone and opioid receptor antagonists that do not penetrate the blood-brain barrier such as methylnaltrexone and alvimopan. Preliminary evidence indicates that peripherally restricted opioid receptor antagonists may act as prokinetic drugs in their own right.

Topics: Animals; Constipation; Gastrointestinal Tract; Humans; Naloxone; Naltrexone; Narcotic Antagonists; Piperidines; Quaternary Ammonium Compounds; Receptors, Opioid

Opioid-induced constipation is a significant problem particularly for end stage cancer patients, methadone users, patients suffering from chronic pain as well as surgical patients. Until recently, there were few efficacious treatment options that did not have significant side effects. Methylnaltrexone is a promising drug for the treatment of opioid-induced constipation. It is an opioid-receptor antagonist that blocks the peripheral gastrointestinal opioid receptors responsible for opioid-induced bowel dysfunction. Due to the drug's polarity, it does not cross the blood-brain barrier; therefore, it does not block the central opioid receptors, thus, retaining effective analgesia. Methylnaltrexone has been recently approved by the FDA in the subcutaneous form for the treatment of opioid-induced bowel dysfunction, whereas the intravenous and oral forms remain under investigation.

Topics: Analgesics, Opioid; Animals; Constipation; Gastrointestinal Transit; Humans; Naltrexone; Quaternary Ammonium Compounds

Chronic pain patients using opioids frequently suffer from constipation which compromises well-being. Such an opioid-induced gastro-intestinal complication can occur regularly in patients in palliative care as well as in analgesic sedated intensive care patients or during prolonged perioperative pain therapy. Discomfort and distress in the affected patients can be so severely pronounced that they would rather suffer from the pain than from the side effect of constipation. Conventional therapy can be insufficient in providing satisfactory relief of constipation, mostly because this opioid-induced bowel hypomotility can be laxative-resistant. Moreover, constipation does not decrease during the course of therapy as do other side effects. It is well known that opioid-induced constipation is mediated via activation of micro-opioid receptors in the gastrointestinal tract. Selective peripheral micro-receptor antagonists (such as methylnaltrexone, Relistor) can effectively treat opioid-induced constipation. An interference with central analgesia does not occur as the molecules cannot pass the blood-brain barrier due to their charged states. A reduction of opioid therapy or the development of withdrawal symptoms can be avoided. Studies have shown that methylnaltrexone is not only safe and efficient for chronically constipated palliative care patients but offers promising therapeutic options for further patient collectives.

Topics: Analgesics, Opioid; Clinical Trials as Topic; Constipation; Critical Care; Humans; Naltrexone; Narcotic Antagonists; Palliative Care; Quaternary Ammonium Compounds

In April 2008, the US FDA granted approval to methylnaltrexone (Relistor), the first peripheral micro-opioid-receptor antagonist for the treatment of opioid-induced constipation in advanced-illness patients receiving palliative care and for whom other laxative therapies failed to achieve adequate results. Methylnaltrexone, a quaternary derivative of naltrexone, introduces a novel mechanism of action that selectively antagonizes the peripheral micro-receptors in the GI tract without effects on the CNS. In clinical trials, subcutaneous methylnaltrexone reversed opioid-induced constipation after the first dose in approximately 50-60% of the patients. In most of the cases, effective laxation occurred within 1 h. The therapeutic benefit was sustained in multiple-dose studies. Owing to the nature of the population studied, safety data are available for approximately 4 months of use. Although it is not the focus of this article, methylnaltrexone's mechanism of action suggests it could be beneficial for other peripheral, opioid-induced adverse effects, such as opioid-related nausea, vomiting, urinary retention, pruritus or postoperative ileus.

Topics: Analgesics, Opioid; Clinical Trials as Topic; Constipation; Defecation; Drug Approval; Gastrointestinal Motility; Humans; Injections, Intravenous; Injections, Subcutaneous; Laxatives; Naltrexone; Narcotic Antagonists; Palliative Care; Quaternary Ammonium Compounds; Treatment Outcome

Constipation is a common problem associated with opiates and opioid compounds used for the treatment of pain and other medical conditions, and can influence patient quality of life. Methylnaltrexone appears effective in the therapy of opioid-induced constipation and will be useful for patients failing to respond to traditional laxative regimens.

Topics: Analgesics, Opioid; Clinical Trials as Topic; Constipation; Dose-Response Relationship, Drug; Drug Interactions; Gastrointestinal Transit; Half-Life; Humans; Infusions, Intravenous; Infusions, Subcutaneous; Laxatives; Naltrexone; Narcotic Antagonists; Postoperative Complications; Quaternary Ammonium Compounds

Constipation and other gastrointestinal symptoms are frequent adverse effects of either short-term postoperative or chronic opioid therapy. The review authors have identified 23 studies to evaluate the efficacy of micro-opioid antagonists for the prevention and treatment of these complications. The data on safety and efficacy of the traditional antagonists naloxone and nalbuphine are insufficient. The results of studies with the newer, peripherally-acting antagonists alvimopan and methylnaltrexone are promising. Methylnaltrexone resulted in four studies with healthy probands in a significant shortening of the gastrointestinal transit time (-52 min). In the postoperative setting, five studies showed a significant improvement of the hazard ratios for different outcomes (e. g., bowel movement, tolerance of solid food) in the alvimopan group. Future studies will be needed to show whether these results can be reproduced in different patient groups on a larger scale. Also, with regard to other pharmacological (e. g., lactulose) and non-pharmacological interventions, the role of the above-mentioned not yet approved medications needs to be defined.

Topics: Analgesics, Opioid; Clinical Trials as Topic; Constipation; Gastrointestinal Transit; Humans; Nalbuphine; Naloxone; Naltrexone; Narcotic Antagonists; Piperidines; Quaternary Ammonium Compounds; Receptors, Opioid, mu

Opioid-induced bowel dysfunction (OBD) is characterized by constipation, incomplete evacuation, bloating, and increased gastric reflux. OBD occurs both acutely and chronically, in multiple disease states, resulting in increased morbidity and reduced quality of life.. To compare the efficacy and safety of traditional and peripherally active opioid antagonists versus conventional interventions for OBD.. We searched MEDLINE, the Cochrane Central Register of Controlled Trials and EMBASE in January 2007. Additional reports were identified from the reference lists of retrieved papers.. Studies were included if they were randomized controlled trials that investigated the efficacy of mu-opioid antagonists for OBD.. Data were extracted by two independent review authors and included demographic variables, diagnoses, interventions, efficacy, and adverse events.. Twenty-three studies met inclusion criteria and provided data on 2871 opioid antagonist-treated patients. The opioid antagonists investigated were alvimopan (nine studies), methylnaltrexone (six), naloxone (seven), and nalbuphine (one). Meta-analysis demonstrated that methylnaltrexone and alvimopan were better than placebo in reversing opioid-induced increased gastrointestinal transit time and constipation, and that alvimopan appears to be safe and efficacious in treating postoperative ileus. The incidence of adverse events with opioid antagonists was similar to placebo and generally reported as mild-to-moderate.. Insufficient evidence exists for the safety or efficacy of naloxone or nalbuphine in the treatment of OBD. Long-term efficacy and safety of any of the opioid antagonists is unknown, as is the incidence or nature of rare adverse events. Alvimopan and methylnaltrexone both show promise in treating OBD, but further data will be required to fully assess their place in therapy.

Topics: Constipation; Defecation; Gastrointestinal Agents; Humans; Intestinal Diseases; Nalbuphine; Naloxone; Naltrexone; Narcotic Antagonists; Opioid-Related Disorders; Piperidines; Quaternary Ammonium Compounds; Receptors, Opioid, mu

To review the mechanisms of action of methylnaltrexone and its effects on opioid bowel dysfunction, as well as its effects on other opioid-induced adverse effects (ADEs), and its potential roles in clinical practice.. A literature search using the MEDLINE and Cochrane Collaboration databases for articles published between 1966 and March 2007 was performed. Additional data sources were obtained from manual searches of recent journal articles, book chapters, and monographs. An updated literature search showed no additional publications.. Abstracts and original preclinical and clinical research reports published in the English language were identified for review. Review articles, commentaries, and news reports of this compound were excluded. Literature related to opioids, opioid receptors, opioid antagonists, methylnaltrexone, opioid-induced bowel dysfunction, constipation, nausea, and vomiting was evaluated and selected based on consideration of the support shown for the proof of concept, mechanistic findings, and timeliness. Fifty-eight original articles from preclinical studies and clinical trials using methylnaltrexone were identified. Pharmacologic action, benefits, and ADEs of methylnaltrexone were reviewed, with a focus on its effects on bowel dysfunction after opioids. Emphases were placed on its receptor binding activities and therapeutically relevant sites of action (peripheral vs central), in which peripheral opioid receptors in the body contribute to physiological and drug-induced effects.. Morphine and related opioids are associated with a number of limiting ADEs, including opioid-induced bowel dysfunction. Methylnaltrexone, a quaternary derivative of naltrexone, blocks peripheral effects of opioids while sparing central analgesic effects. It is currently under late-stage clinical investigation for the treatment of opioid-induced constipation in patients with advanced illness. Reported results showed the drug to be generally well-tolerated. The rapid reversal of constipation is very encouraging. Hastening postoperative discharge may also be possible.. Methylnaltrexone has the potential to prevent or treat opioid-induced peripherally mediated ADEs on bowel dysfunction without interfering with central analgesia. The study of methylnaltrexone leads to a greater understanding of the mechanisms of action of opioid pharmacology.

Topics: Analgesics, Opioid; Constipation; Humans; Naltrexone; Narcotic Antagonists; Quaternary Ammonium Compounds

Opioid medications are frequently used in pain and palliative care patients with malignancy to manage symptoms such as pain and dyspnea. However, opiates are associated with various side effects. Constipation is a particularly problematic and common side effect of opioid pharmacology. Opioid antagonists have been studied in the management of opioid-induced constipation. Methylnaltrexone (MNTX) is a peripheral opioid antagonist currently under clinical investigation. It offers the potential to reverse undesirable side effects without reversing analgesia.. This article attempts to review existing clinical data, focusing on antagonism of opioid-induced adverse effects on the gastrointestinal system.. MNTX seems to be well tolerated with limited or transient side effects. MNTX has been shown to improve oral-cecal transit times in opioid treated patients, induce laxation in chronic opioid users, and neither reverses the analgesic effects of morphine nor cause withdrawal symptoms.. Larger clinical trials of MNTX are still necessary to support its use as a standard for treatment of opioid-induced constipation.

Topics: Analgesics, Opioid; Constipation; Humans; Naltrexone; Narcotic Antagonists; Quaternary Ammonium Compounds

Cancer-related constipation is common and a significant detractor from patient quality of life. It has many possible causes and is still not well understood. Information is lacking on therapies for cancer-related constipation among current medications approved by the US Food and Drug Administration (FDA). Most agents have only been formally tested in comparison with placebo in chronic idiopathic constipation if at all. Few comparative studies of laxatives have been performed to establish superiority or synergy. As we understand more about the physiology of the gastrointestinal tract, new targeted therapies have become available. These include a selective chloride channel activator, lubiprostone, and a selective 5HT4 serotonin receptor agonist, tegaserod, both of which have been FDA approved for chronic idiopathic constipation. The role of these agents in cancer-related constipation remains to be seen. On the horizon are two investigational peripherally acting opioid receptor antagonists, alvimopan and methylnaltrexone. Preliminary results in cancer-related constipation suggest that these agents may be important additions to our treatment repertoire.

Topics: Alprostadil; Constipation; Fatty Acids; Gastrointestinal Agents; Humans; Indoles; Lubiprostone; Naltrexone; Narcotic Antagonists; Neoplasms; Piperidines; Quaternary Ammonium Compounds; Serotonin Receptor Agonists

Methylnaltrexone is a peripheral opioid receptor antagonist undergoing phase III clinical trials for the treatment of opioid-induced constipation in patients with advanced medical illness who are being treated with narcotics for pain. The compound does not cross the blood-brain barrier in humans and reverses the opioid effects without interfering with pain relief. Some opioid-induced adverse events that the drug may potentially target include constipation, nausea/vomiting, cough suppression and urinary retention. Methylnaltrexone was discovered by researchers at the University of Chicago, Chicago, Illinois, USA and is in joint development with Progenics Pharmaceuticals and Wyeth Pharmaceuticals. Progenics is conducting clinical trials with three methylnaltrexone dosage forms: subcutaneous, IV and oral. Progenics plans to complete the clinical development of methylnaltrexone alone, after which potential pharmaceutical or biotechnology partners will be looked at to provide financial support and marketing expertise, particularly outside the US market. In December 2005, Progenics and Wyeth Pharmaceutical (Wyeth) entered into an exclusive, worldwide agreement for the joint development and commercialisation of methylnaltrexone for the treatment of opioid-induced side effects, including constipation and postoperative bowel dysfunction. Under the terms of the licensing agreement, Wyeth has worldwide rights to the compound and Progenics retains the option to co-promote methylnaltrexone in the US. The companies will collaborate on the worldwide development of methylnaltrexone. Under the terms of the agreement, Wyeth has made an up-front payment to Progenics and will also make additional milestone payments. Wyeth will also pay Progenics royalties on worldwide sales, and co-promotion fees within the US. Wyeth is also responsible for all future development and commercialisation costs. Wyeth will develop oral methylnaltrexone worldwide. Progenics will lead the US development of subcutaneous and intravenous methylnaltrexone, while Wyeth will lead development of these parenteral products outside the US.UR Labs licensed methylnaltrexone from the University of Chicago. In October 2001, Progenics in-licensed the methynaltrexone patent portfolio in exchange for rights to future methynaltrexone royalties. In December 2005, Progenics acquired a substantial portion of the royalty and milestone payments in exchange for 686,000 shares of Progenic's common stock and 2.6 million US

Topics: Clinical Trials as Topic; Colic; Constipation; Flatulence; Humans; Injections, Intravenous; Naltrexone; Narcotic Antagonists; Quaternary Ammonium Compounds; Treatment Outcome

The gut is a neurological organ, which implies that many neuroactive drugs such as opioid analgesics can seriously disturb gastrointestinal function, because many of the transmitters and transmitter receptors present in the brain are also found in the enteric nervous system. One of the most common manifestations of opioid-induced bowel dysfunction is constipation which results from blockade of peristalsis and intestinal fluid secretion. The discovery of opioid receptor antagonists with a peripherally restricted site of action, such as N-methylnaltrexone and alvimopan, makes it possible to normalize bowel function in opiate-treated patients without compromising central opioid analgesia. There is emerging evidence that opioid receptor antagonists may also have prokinetic actions, reversing pathological states of gastrointestinal hypomotility that are due to overactivity of the enteric opioid system.

Topics: Analgesics, Opioid; Animals; Constipation; Enteric Nervous System; Gastrointestinal Motility; Humans; Naltrexone; Narcotic Antagonists; Piperidines; Quaternary Ammonium Compounds; Receptors, Opioid

Opioid treatment for postoperative or chronic pain is frequently associated with adverse effects, the most common being dose-limiting and debilitating bowel dysfunction. Postoperative ileus, although attributable to surgical procedures, is often exacerbated by opioid use during and following surgery. Postoperative ileus is marked by increased inhibitory neural input, heightened inflammatory responses, decreased propulsive movements and increased fluid absorption in the gastrointestinal tract. The use of opioids for chronic pain is characterised by a constellation of symptoms including hard dry stools, straining, incomplete evacuation, bloating, abdominal distension and increased gastroesophageal reflux. The current management of opioid-induced bowel dysfunction among patients receiving opioid analgesics consists primarily of nonspecific ameliorative measures. Intensive investigations into the mode of action of opioids have characterised three opioid receptor classes -mu, delta and kappa- that mediate the myriad of peripheral and central actions of opioids. Activation of mu-opioid receptors in the gastrointestinal tract is responsible for inhibition of gut motility, whereas receptors in the central nervous system mediate the analgesic actions of opioids. Blocking peripheral opioid receptors in the gut is therefore a logical therapeutic target for managing opioid-induced bowel dysfunction. Available opioid antagonists such as naloxone are of limited use because they are readily absorbed, cross the blood-brain barrier, and act at central opioid receptors to reverse analgesia and elicit opioid withdrawal. Methylnaltrexone and alvimopan are recently developed opioid antagonists with activity that is restricted to peripheral receptors. Both have recently shown the ability to reverse opioid-induced bowel dysfunction without reversing analgesia or precipitating central nervous system withdrawal signs in non-surgical patients receiving opioids for chronic pain. In addition, recent clinical studies with alvimopan suggest that it may normalise bowel function without blocking opioid analgesia in abdominal laparotomy patients with opioid-related postoperative ileus.

Topics: Constipation; Digestive System; Gastrointestinal Motility; Gastrointestinal Transit; Humans; Intestinal Obstruction; Naltrexone; Narcotic Antagonists; Narcotics; Postoperative Complications; Quaternary Ammonium Compounds; Receptors, Opioid; Water-Electrolyte Balance

Progenics is developing methylnaltrexone (MNTX), an opioid antagonist licensed from UR Labs and the University of Chicago, for the potential treatment of the side effects of opioid pain therapy, such as constipation and post-operative bowel dysfunction. MNTX was discovered at the University of Chicago and subsequently licensed by UR Labs. In October 2001, Progenics entered into an agreement with UR Labs to obtain exclusive worldwide rights to the drug [423791]. MNTX is in phase II trials, with phase III studies expected to begin in 2002 [423791]. In October 2001, a double-blind, randomized, phase II study evaluating sc MNTX in cancer patients for the treatment of opioid-induced constipation was initiated at the University of Chicago Medical Center [423791]. In December 2001, the company stated that it was preparing to initiate phase IIb trials of the compound in opioid-induced constipation and post-operative bowel dysfunction [423791], [432507]. These trials were initiated in February 2002 [440995].

Topics: Analgesics, Opioid; Animals; Constipation; Humans; Naltrexone; Narcotic Antagonists; Quaternary Ammonium Compounds; Randomized Controlled Trials as Topic; Structure-Activity Relationship

To describe the role of opioid antagonists in the treatment of opioid-induced constipation and pruritus.. A MEDLINE search was performed (1966-February 2000) for narcotics and opioid antagonists. Results were limited to English-language and clinical trials. Background information was obtained from pharmacology and pharmacotherapy references and review articles. Hand searching of selected bibliographies yielded several references.. Studies were reviewed that examined the use of naloxone, naltrexone, and methylnaltrexone for opioid-related constipation and pruritus. Selected citations included various clinical trials and case series.. Opioid agents are used for cancer and nonmalignant pain. Peripheral opioid receptor stimulation due to endogenous (i.e., endorphins) or exogenous (i.e., morphine) stimulants may result in negative adverse effects, including constipation and pruritus. Adjuvant agents, such as laxatives and antihistamines, are often used to treat these adverse effects, but are themselves associated with adverse effects and are sometimes ineffective. Opioid antagonists have demonstrated reversal of peripheral opioid receptor stimulation. Clinical trials show adequate maintenance of pain control, as well as decreases in opioid-induced constipation and pruritus.. Opioid antagonists offer a therapeutic alternative to conventional adjuvant agents, with the risk of loss of analgesia at higher doses. Methylnaltrexone offers the advantage of peripheral action only, therefore not reversing analgesia. Results are promising; however, larger clinical trials are necessary before opioid antagonists become the standard of care for opioid-induced constipation and pruritus.

Topics: Clinical Trials as Topic; Constipation; Humans; Morphine; Naloxone; Naltrexone; Narcotic Antagonists; Narcotics; Pruritus; Quaternary Ammonium Compounds

Opioid bowel dysfunction (OBD) is a common adverse effect associated with opioid therapy. OBD is commonly described as constipation; however, it is a constellation of adverse gastrointestinal (GI) effects, which also includes abdominal cramping, bloating, and gastroesophageal reflux. The mechanism for these effects is mediated primarily by stimulation of opioid receptors in the GI tract. In patients with pain, uncontrolled symptoms of OBD can add to their discomfort and may serve as a barrier to effective pain management, limiting therapy, or prompting discontinuation. Patients with cancer may have disease-related constipation, which is usually worsened by opioid therapy. However, OBD is not limited to cancer patients. A recent survey of patients taking opioid therapy for pain of noncancer origin found that approximately 40% of patients experienced constipation related to opioid therapy (<3 complete bowel movements per week) compared with 7.6% in a control group. Of subjects who required laxative therapy, only 46% of opioid-treated patients (control subjects, 84%) reported achieving the desired treatment results >50% of the time. Laxatives prescribed prophylactically and throughout opioid therapy may improve bowel movements in many patients. Nevertheless, a substantial number of patients will not obtain adequate relief of OBD because of its refractory nature. Naloxone and other tertiary opioid receptor antagonists effectively reduce the symptoms of constipation in opioid-treated patients. However, because they also act centrally, they may provoke opioid withdrawal symptoms or reverse analgesia in some patients. There are 2 peripherally selective opioid receptor antagonists, methylnaltrexone and ADL 8-2698 (Adolor Corporation, Exton, PA, USA), that are currently under investigation for their use in treating OBD. Early studies confirm that they are effective at normalizing bowel function in opioid-treated patients without entering the central nervous system and affecting analgesia. With a better understanding of the prevalence of OBD and its pathophysiology, a more aggressive approach to preventing and treating OBD is possible and will likely improve the quality of life of patients with pain.

Topics: Analgesics, Opioid; Cathartics; Colic; Constipation; Data Collection; Gastroesophageal Reflux; Humans; Incidence; Intestines; Naltrexone; Narcotic Antagonists; Prevalence; Quaternary Ammonium Compounds; United States

Opioids are widely used analgesics in patients with advanced cancer. However, their effectiveness for pain relief is often limited by the most frequently occurring side effect, opioid bowel dysfunction (OBD). Because conventional laxation measures are often ineffective in treating OBD, alternative approaches need to be investigated. Opioid action on the gut appears to be mediated mainly by receptors in the gastrointestinal (GI) tract rather than by those in the central nervous system (CNS). Opioid antagonists, such as naloxone, naltrexone, and nalmefene, have been studied as a means of antagonizing the peripheral effects of opioids, but these agents can enter the CNS and reverse analgesia or cause opioid withdrawal symptoms. Methylnaltrexone (MNTX) is a novel quaternary derivative of naltrexone that does not cross the blood-brain barrier and acts as a selective peripheral opioid receptor antagonist. In normal volunteers, intravenous or oral MNTX reverses opioid-induced reduction in bowel motility without affecting analgesia. Bioavailability of MNTX is low after oral administration, and plasma levels do not correlate with its actions in the gut, suggesting a predominantly local luminal action of MNTX on the gut. In patients receiving long-term opioid therapy, MNTX administered intravenously or orally was effective in reducing the delay in oral-cecal transit and eliciting laxation responses in all subjects without causing withdrawal symptoms. MNTX is a peripherally selective opioid antagonist that may have clinical utility in managing OBD with minimal adverse effects.

Topics: Analgesics, Opioid; Animals; Constipation; Dose-Response Relationship, Drug; Gastrointestinal Motility; Gastrointestinal Transit; Humans; Intestines; Morphine; Naltrexone; Narcotic Antagonists; Quaternary Ammonium Compounds; Receptors, Opioid

Topics: Adult; Analgesics, Opioid; Chronic Pain; Constipation; Double-Blind Method; Humans; Naltrexone; Opioid-Induced Constipation; Quaternary Ammonium Compounds; Treatment Outcome

Peripherally acting μ-opioid receptor antagonists such as methylnaltrexone (MNTX, Relistor. This post hoc analysis of pooled data from 3 randomized, placebo-controlled trials included cancer patients with OIC who received MNTX or placebo. Endpoints included changes from baseline in pain scores, rescue-free laxation (RFL) within 4 or 24 h of the first dose, and treatment-emergent adverse events (TEAEs), including those potentially related to opioid withdrawal symptoms.. Among 356 cancer patients in the pooled population, 47 (MNTX n = 27; placebo n = 20) had brain metastases and 309 (MNTX n = 172; placebo n = 137) did not have brain metastases. No significant differences in current pain, worst pain, or change in pain scores from baseline were observed between patients treated with MNTX or placebo. Among patients with brain metastases, a significantly greater proportion of patients who received MNTX versus placebo achieved an RFL within 4 h after the first dose (70.4% vs 15.0%, respectively, p = 0.0002). TEAEs were similar between treatment groups and were generally gastrointestinal in nature and not related to opioid withdrawal.. Focal disruptions of the BBB caused by brain metastases did not appear to alter central nervous system penetrance of MNTX.

Topics: Adult; Aged; Aged, 80 and over; Analgesics, Opioid; Brain Neoplasms; Central Nervous System; Constipation; Double-Blind Method; Female; Humans; Male; Middle Aged; Naltrexone; Quaternary Ammonium Compounds

Methylnaltrexone, a peripherally acting µ-opioid receptor antagonist approved for the treatment of opioid-induced constipation (OIC), has restricted diffusion across the blood-brain barrier (BBB) and has not been demonstrated to impact opioid-induced central analgesia. Age-related changes in BBB permeability may compromise methylnaltrexone's restricted diffusion and alter opioid-induced central analgesic effects.. This analysis evaluated whether opioid analgesia is compromised in older adults receiving methylnaltrexone for OIC.. The analysis included adults diagnosed with OIC who received opioids for pain management and who had a terminal illness or chronic nonmalignant pain. Data were pooled from four randomized, double-blind trials and stratified by age (< 65 years and ≥ 65 years). Endpoints included pain intensity scores, symptoms of opioid withdrawal, treatment-related adverse events (TRAEs), and rescue-free laxation (RFL) within 4 h of treatment.. Overall, 1323 patients were < 65 years of age (n = 908, methylnaltrexone; n = 415, placebo) and 304 patients were ≥ 65 years of age (n = 171, methylnaltrexone; n = 133, placebo). Nonsignificant pain intensity score reductions were observed in all groups. In the older cohort, measures of opioid withdrawal did not show statistical differences from baseline in either the methylnaltrexone or placebo groups. The most frequently reported TRAEs were abdominal pain, flatulence, and nausea. Relative to the first dose, gastrointestinal TRAEs potentially related to opioid withdrawal declined with the second dose and were comparable with placebo, regardless of age. RFL response within 4 h of methylnaltrexone treatment increased significantly in both age cohorts relative to placebo.. Methylnaltrexone use did not adversely affect pain control, opioid withdrawal effects, or AEs while providing effective RFL, regardless of age. These results suggest that age does not appear to influence the safety and efficacy of methylnaltrexone for OIC. Further research is needed to assess the impact of other factors that alter BBB permeability, such as dementia, stroke, or drug interactions, on the safety and efficacy of methylnaltrexone.. Study 302, NCT00402038; study 3200K1-4000, NCT00672477; study 3200K1-3356, NCT00529087; study 3201, NCT01186770.

Topics: Age Factors; Aged; Analgesics, Opioid; Constipation; Humans; Naltrexone; Opioid-Induced Constipation; Quaternary Ammonium Compounds; Treatment Outcome

Constipation can be a significant problem in critically unwell patients, associated with detrimental outcomes. Opioids are thought to contribute to the mechanism of bowel dysfunction. We tested if methylnaltrexone, a pure peripheral mu-opioid receptor antagonist, could reverse opioid-induced constipation.. The MOTION trial is a multi-centre, double blind, randomised placebo-controlled trial to investigate whether methylnaltrexone alleviates opioid-induced constipation (OIC) in critical care patients. Eligibility criteria included adult ICU patients who were mechanically ventilated, receiving opioids and were constipated (had not opened bowels for a minimum 48 h) despite prior administration of regular laxatives as per local bowel management protocol. The primary outcome was time to significant rescue-free laxation. Secondary outcomes included gastric residual volume, tolerance of enteral feeds, requirement for rescue laxatives, requirement for prokinetics, average number of bowel movements per day, escalation of opioid dose due to antagonism/reversal of analgesia, incidence of ventilator-associated pneumonia, incidence of diarrhoea and Clostridium difficile infection and finally 28 day, ICU and hospital mortality.. A total of 84 patients were enrolled and randomized (41 to methylnaltrexone and 43 to placebo). The baseline demographic characteristics of the two groups were generally well balanced. There was no significant difference in time to rescue-free laxation between the groups (Hazard ratio 1.42, 95% CI 0.82-2.46, p = 0.22). There were no significant differences in the majority of secondary outcomes, particularly days 1-3. However, during days 4-28, there were fewer median number of bowel movements per day in the methylnaltrexone group, (p = 0.01) and a greater incidence of diarrhoea in the placebo group (p = 0.02). There was a marked difference in mortality between the groups, with ten deaths in the methylnaltrexone group and two in the placebo group during days 4-28 (p = 0.007).. We found no evidence to support the addition of methylnaltrexone to regular laxatives for the treatment of opioid-induced constipation in critically ill patients; however, the confidence interval was wide and a clinically important difference cannot be excluded.

Topics: Adult; Analgesics, Opioid; Constipation; Critical Care; Humans; Naltrexone; Opioid-Induced Constipation; Quaternary Ammonium Compounds

Methylnaltrexone Reverses Chronic Opioid-induced Constipation: A Randomized, Controlled Trial. By Yuan CS, Foss JF, O'Connor M, Osinski J, Karrison T, Moss J, Roizen MF. JAMA 2000; 130:142-8. Reprinted with permission.. Constipation is the most common chronic adverse effect of opioid pain medications in patients who require long-term opioid administration, such as patients with advanced cancer, but conventional measures for ameliorating constipation often are insufficient.. To evaluate the efficacy of methylnaltrexone, the first peripheral opioid receptor antagonist, in treating chronic methadone-induced constipation.. Double-blind, randomized, placebo-controlled trial conducted between May 1997 and December 1998.. Clinical research center of a university hospital.. Twenty-two subjects (9 men and 13 women; mean [SD] age, 43.2 [5.5] years) enrolled in a methadone maintenance program and having methadone-induced constipation.. Laxation response, oral-cecal transit time, and central opioid withdrawal symptoms were compared between the 2 groups.. The 11 subjects in the placebo group showed no laxation response, and all 11 subjects in the intervention group had laxation response after intravenous methylnaltrexone administration (P<.001). The oral-cecal transit times at baseline for subjects in the methylnaltrexone and placebo groups averaged 132.3 and 126.8 minutes, respectively. The average (SD) change in the methylnaltrexone-treated group was -77.7 (37.2) minutes, significantly greater than the average change in the placebo group (-1.4 [12.0] minutes; P<.001). No opioid withdrawal was observed in any subject, and no significant adverse effects were reported by the subjects during the study.. Our data demonstrate that intravenous methylnaltrexone can induce laxation and reverse slowing of oral cecal-transit time in subjects taking high opioid dosages. Low-dosage methylnaltrexone may have clinical utility in managing opioid-induced constipation.

Topics: Adult; Analgesics, Opioid; Constipation; Double-Blind Method; Female; Humans; Male; Naltrexone; Narcotic Antagonists; Quaternary Ammonium Compounds; Treatment Outcome

Methylnaltrexone, a peripherally acting µ-opioid receptor antagonist, alleviates opioid-induced constipation. Understanding its long-term safety and efficacy profile in patients with chronic noncancer pain is warranted given the persistence of opioid-induced constipation.. In this phase 3, multicenter, open-label trial, adults with chronic noncancer pain (N = 1034) received subcutaneous methylnaltrexone 12 mg once daily for 48 weeks.. The most common adverse events were gastrointestinal related (e.g., abdominal pain, diarrhea, nausea) and were mild to moderate in intensity. Only 15.2% of patients discontinued because of an adverse event. Serious cardiac-related adverse events occurred in nine patients. Of the seven instances of major adverse coronary events reported, three were adjudicated after external review; all instances occurred in patients with cardiovascular risk factors. Methylnaltrexone elicited a bowel movement within four hours in 34.1% of the injections throughout the 48-week treatment period.. Change from baseline in mean weekly bowel movement rate, Bowel Movement Straining Scale score, Bristol Stool Scale score, and mean percentage of patients with complete evacuation from baseline to week 48 were significantly improved ( P  < 0.001 for all). Long-term subcutaneous methylnaltrexone was well tolerated, with no new safety concerns, and provided consistent opioid-induced constipation relief in patients with chronic noncancer pain.

Topics: Adult; Aged; Analgesics, Opioid; Chronic Pain; Constipation; Female; Humans; Injections, Subcutaneous; Male; Middle Aged; Naltrexone; Narcotic Antagonists; Quaternary Ammonium Compounds; Time

Methylnaltrexone is a peripherally acting mu-opioid receptor antagonist that has been shown to relieve severe opioid-induced constipation (OIC) in patients with advanced disease receiving palliative care. Its efficacy remains unknown in cancer patients who are not terminally ill. The primary aim of this study was to evaluate the efficacy of methylnaltrexone over 48 h in cancer patients who were not terminally ill.. In this single-dose phase II trial, cancer patients with a prognosis of ≥3 months and OIC with <3 laxations during the preceding week were eligible. The primary endpoint was a rescue-free laxation ≤4 h after a single dose of methylnaltrexone. Friedman's two-way analysis of variance was conducted for the number of laxations, pain and withdrawal scales, and laxation- and constipation-related symptoms. Univariate/bivariate Cox proportional hazard models for laxation times were employed.. Twelve patients received methylnaltrexone. Eleven patients had an ECOG performance status of 1 or 2. Four (33.3 %) and 5 (41.7 %) patients had rescue-free laxation within 4 and 24 h, respectively, and 10 (83.3 %) had laxation within 48 h (p = 0.006). Difficulty passing a stool improved significantly over 48 h (p = 0.029). The bivariate Cox models revealed that a shorter time to laxation was associated with a higher baseline morphine equivalent daily dose (hazard ratio, 1.02 per 1 mg; p = 0.018) and a smaller number of laxations in the preceding week (hazard ratio, 0.13 per one laxation; p = 0.035). Patients tolerated methylnaltrexone well without opioid withdrawal.. Methylnaltrexone may relieve severe OIC in cancer patients who are not terminally ill. A larger prospective study is justified in this population. (NCT01004393, https://clinicaltrials.gov/show/NCT01004393 ).

Topics: Adult; Aged; Aged, 80 and over; Analgesics, Opioid; Constipation; Female; Humans; Injections, Subcutaneous; Male; Middle Aged; Naltrexone; Narcotic Antagonists; Neoplasm Staging; Neoplasms; Prognosis; Quaternary Ammonium Compounds

Subcutaneous methylnaltrexone, a peripherally acting μ-opioid receptor antagonist, improves opioid-induced constipation (OIC) in patients with chronic noncancer pain. An oral methylnaltrexone formulation has been developed.. In this phase 3, double-blind trial, adults with chronic noncancer pain receiving opioid doses of ≥ 50 mg/day oral morphine equivalents with OIC were randomly assigned to oral methylnaltrexone (150, 300, or 450 mg) or placebo once daily (QD) for 4 weeks followed by as-needed dosing for 8 weeks. Patients who had ≥ 3 rescue-free bowel movements (RFBMs)/week, with an increase of ≥ 1 RFBM/week from baseline for ≥ 3 of 4 weeks during the QD period, were responders.. Overall, 803 patients were included in the analyses. A significantly greater percentage of patients had an increase in mean percentage of dosing days resulting in an RFBM within 4 hours of dosing during weeks 1 through 4 (QD period; primary endpoint) with methylnaltrexone (300 mg/day [24.6%; P = 0.002] and 450 mg/day [27.4%; P < 0.0001]) vs. placebo (18.2%). The percentage of responders (49.3% for 300 mg [P = 0.03] and 51.5% for 450 mg [P = 0.005] vs. 38.3% with placebo) and change from baseline in mean number of weekly RFBMs (difference vs. placebo, 0.5 for 300 mg [P = 0.03] and 0.5 for 450 mg [P = 0.02]) was significantly greater with methylnaltrexone 300 and 450 mg/day vs. placebo during the QD period. All dosages of oral methylnaltrexone were well tolerated.. Oral methylnaltrexone was efficacious and well tolerated for OIC in patients with chronic noncancer pain, particularly the 450-mg dose.

Topics: Administration, Oral; Adult; Aged; Analgesics, Opioid; Chronic Pain; Constipation; Double-Blind Method; Female; Humans; Injections, Subcutaneous; Male; Middle Aged; Naltrexone; Narcotic Antagonists; Quaternary Ammonium Compounds; Receptors, Opioid, mu; Treatment Outcome

Methylnaltrexone (MNTX) is approved for subcutaneous treatment (MNTX-SC) of opioid induced constipation. MNTX in oral immediate-release (MNTX-IR) and extended-release (MNTX-ER) dosage forms may antagonize the opioid induced delay in oro-cecal transit time (OCT) as measured by using radiolabeled lactulose. Because lactulose acts laxative by its own and efficacy of MNTX on colon transit time (CTT) was unknown, the opioid antagonistic effects MNTX-IR and MNTX-ER (both 500 mg) relative to MNTX-SC (12 mg) were evaluated in 15 healthy subjects with loperamide (LOP, 3 × 4 mg, 12 hourly) induced experimental constipation using the sulfasalazine/sulfapyridine method and radio-opaque markers to measure OCT and whole gut transit time (WGT). MNTX-ER significantly antagonized the LOP effects in 12 of our 15 subjects who responded to LOP with prolongation of WGT by 20.6-74.1 h (OCT by 0.50-10.5 h, CTT by 18.3-73.6 h). MNTX-SC and MNTX-IR were without significant influence. Compared to MNTX-SC, bioavailability of MNTX-IR and MNTX-ER was 1.53-5.49% and 0.11-1.24%, respectively. MNTX-SC and MNTX-IR achieved active serum levels only for ∼ 3-5 h. MNTX-ER antagonized the opioid-induced delay of CTT most likely by local effects on µ-opioid receptors in the colon.

Topics: Adult; Antidiarrheals; Constipation; Delayed-Action Preparations; Dose-Response Relationship, Drug; Drug Antagonism; Female; Gastrointestinal Motility; Gastrointestinal Transit; Humans; Injections, Subcutaneous; Loperamide; Male; Naltrexone; Narcotic Antagonists; Quaternary Ammonium Compounds; Young Adult

Gastrointestinal dysmotility and constipation are common problems in intensive care patients. The majority of critical care patients are sedated with opioids to facilitate tolerance of endotracheal tubes and mechanical ventilation, which inhibit gastrointestinal motility and lead to adverse outcomes. Methylnaltrexone is a peripheral opioid antagonist that does not cross the blood-brain barrier and can reverse the peripheral side effects of opioids without affecting the desired central properties. This trial will investigate whether methylnaltrexone can reverse opioid-induced constipation and gastrointestinal dysmotility.. This is a single-centre, multisite, double-blind, randomised, placebo-controlled trial. 84 patients will be recruited from 4 intensive care units (ICUs) within Imperial College Healthcare NHS Trust. Patients will receive intravenous methylnaltrexone or placebo on a daily basis if they are receiving opioid infusion to facilitate mechanical ventilation and have not opened their bowels for 48 hours. All patients will receive standard laxatives as per the clinical ICU bowel protocol prior to randomisation. The primary outcome of the trial will be time to significant rescue-free laxation following randomisation. Secondary outcomes will include tolerance of enteral feed, gastric residual volumes, incidence of pneumonia, blood stream and Clostridium difficile infection, and any reversal of central opioid effects.. The trial protocol, the patient/legal representative information sheets and consent forms have been reviewed and approved by the Harrow Research Ethics Committee (REC Reference 14/LO/2004). An independent Trial Steering Committee and Data Monitoring Committee are in place, with patient representation. On completion, the trial results will be published in peer-reviewed journals and presented at national and international scientific meetings.. 2014-004687-37; Pre-results.

Topics: Adult; Analgesics, Opioid; Blood-Brain Barrier; Constipation; Critical Care; Female; Gastrointestinal Motility; Humans; Laxatives; Male; Naltrexone; Narcotic Antagonists; Quaternary Ammonium Compounds

Methylnaltrexone (MNTX), a peripherally acting μ-opioid receptor (MOR) antagonist, is FDA-approved for treatment of opioid-induced constipation (OIC). Preclinical data suggest that MOR activation can play a role in cancer progression and can be a target for anticancer therapy.. Pooled data from advanced end-stage cancer patients with OIC, despite laxatives, treated in two randomized (phase III and IV), placebo-controlled trials with MNTX were analyzed for overall survival (OS) in an unplanned post hoc analysis. MNTX or placebo was given subcutaneously during the double-blinded phase, which was followed by the open-label phase, allowing MNTX treatment irrespective of initial randomization.. In two randomized, controlled trials, 229 cancer patients were randomized to MNTX (117, 51%) or placebo (112, 49%). Distribution of patients' characteristics and major tumor types did not significantly differ between arms. Treatment with MNTX compared with placebo [76 days, 95% confidence interval (CI) 43-109 versus 56 days, 95% CI 43-69; P = 0.033] and response (laxation) to treatment compared with no response (118 days, 95% CI 59-177 versus 55 days, 95% CI 40-70; P < 0.001) had a longer median OS, despite 56 (50%) of 112 patients ultimately crossing over from placebo to MNTX. Multivariable analysis demonstrated that response to therapy [hazard ratio (HR) 0.47, 95% CI 0.29-0.76; P = 0.002) and albumin ≥3.5 (HR 0.46, 95% CI 0.30-0.69; P < 0.001) were independent prognostic factors for increased OS. Of interest, there was no difference in OS between MNTX and placebo in 134 patients with advanced illness other than cancer treated in these randomized studies (P = 0.88).. This unplanned post hoc analysis of two randomized trials demonstrates that treatment with MNTX and, even more so, response to MNTX are associated with increased OS, which supports the preclinical hypothesis that MOR can play a role in cancer progression. Targeting MOR with MNTX warrants further investigation in cancer therapy.. NCT00401362, NCT00672477.

Topics: Adult; Aged; Analgesics, Opioid; Constipation; Disease-Free Survival; Female; Humans; Kaplan-Meier Estimate; Laxatives; Male; Middle Aged; Naltrexone; Neoplasms; Quaternary Ammonium Compounds; Receptors, Opioid, mu

Subcutaneous methylnaltrexone is efficacious and well tolerated in inducing bowel movements in patients with advanced illness and opioid-induced constipation (OIC); factors determining optimal responsiveness to OIC treatment, however, have not been elucidated. This post hoc responder analysis examined the influence of demographic and baseline characteristics on methylnaltrexone efficacy and tolerability in this population.. Data were pooled from 2 randomized, double-blind, placebo-controlled, phase 3 studies of subcutaneous methylnaltrexone (0.15 and 0.30 mg/kg) [ClinicalTrials.gov identifiers: Study 301 - NCT00401362; Study 302 - NCT00402038]. Subgroup analyses of the primary outcome, percentage of patients with rescue medication-free bowel movements (RFBM) within 4 hours of first dose, were conducted for age, sex, primary diagnosis, baseline constipation-related distress score, and baseline oral morphine equivalent dose.. More than 50% of 165 patients treated with either methylnaltrexone dose experienced a RFBM within 4 hours vs. 14.6% of 123 placebo-treated patients (P < 0.0001 for both methylnaltrexone doses vs. placebo). Methylnaltrexone response was significantly greater than placebo response in all subgroups (P < 0.01). The largest differences vs. placebo were observed for patients taking methylnaltrexone 0.30 mg/kg with a noncancer primary diagnosis (70.0% [methylnaltrexone] vs. 12.8% [placebo]; P < 0.001) and for patients taking methylnaltrexone 0.30 mg/kg maintained on ≥ 150 mg/day baseline morphine equivalent doses (73.3% vs. 16.7%; P < 0.0001). Common adverse events were abdominal pain (pooled methylnaltrexone: 27.9%, placebo: 9.8%), flatulence (13.3%, 5.7%), and nausea (10.9%, 4.9%). Tolerability was comparable across subgroups.. Subcutaneous methylnaltrexone provides a rapid, robust, and consistent RFBM response in patients with advanced illness and OIC. Methylnaltrexone 0.30 mg/kg may elicit particularly favorable responses in select patient populations.

Topics: Adult; Aged; Analgesics, Opioid; Constipation; Double-Blind Method; Female; Humans; Male; Middle Aged; Naltrexone; Narcotic Antagonists; Quaternary Ammonium Compounds; Treatment Outcome

Subcutaneous methylnaltrexone (MNTX), dosed based on body weight, is efficacious and well tolerated in inducing bowel movements in patients with advanced illness and opioid-induced constipation (OIC); however, fixed-dose administration of MNTX may improve ease of administration.. The study objective was to assess safety and efficacy of fixed-dose MNTX in two phase 4 trials.. In a double-blind, randomized, placebo-controlled trial (RCT), patients with advanced illness and OIC received MNTX (8 mg or 12 mg by body weight [38 kg to <62 kg or ≥62 kg, respectively]) or placebo every other day (QOD) for two weeks. Patients completing the RCT could enroll in an open-label extension (OLE) study with MNTX administered as needed (PRN). The primary endpoint was percentage of patients with a rescue-free bowel movement (RFBM) within four hours after ≥2 of the first 4 doses in the first week.. In the RCT, 116 and 114 patients received MNTX and placebo, respectively, and 149 patients continued to the OLE study. The percentage of patients achieving primary endpoint was 62.9% and 9.6% for MNTX and placebo groups, respectively (p<0.0001). Median time to RFBM after the first dose was 0.8 hour and 23.6 hours in MNTX and placebo groups, respectively (p<0.0001). Efficacy results during the OLE study were consistent with the RCT. MNTX demonstrated a favorable safety profile in the RCT and OLE study.. Fixed-dose MNTX administered QOD in the RCT and PRN in the OLE study demonstrated robust efficacy and was well tolerated in treating OIC in patients with advanced illness.

Topics: Aged; Analgesics, Opioid; Constipation; Double-Blind Method; Female; Humans; Injections, Subcutaneous; Male; Middle Aged; Naltrexone; Narcotic Antagonists; Patient Safety; Placebos; Quaternary Ammonium Compounds; Severity of Illness Index

Pediatric oncology patients can experience opioid-induced constipation, which may not respond to laxative treatment. Methylnaltrexone is an opioid receptor antagonist that can reverse opioid-induced constipation without affecting analgesia. Published literature on the use of methylnaltrexone in children is very limited. This retrospective review describes the effectiveness and safety of methylnaltrexone for opioid-induced constipation in pediatric oncology patients.. A retrospective review of health records was conducted for pediatric oncology in-patients who were prescribed methylnaltrexone between May 2008 and September 2012 at The Hospital for Sick Children. Demographic, clinical, efficacy, and safety data were collected, including; opioid, laxative, and methylnatrexone dosing and frequency.. Fifteen patients (median age: 14 years, range: 4-17 years) received methylnaltrexone; 12 received a single dose while three received multiple doses. At the time of methylnaltrexone administration, patients were receiving a median oral morphine dose equivalent of 5.7 mg/kg/day (range: 1.5-29.2 mg/kg/day) and had not had any bowel movements for several days despite treatment with multiple laxatives. Methylnaltrexone was given at a mean dose of 0.15 ± 0.02 mg/kg/dose (range: 3-12 mg/dose) as a subcutaneous injection. After 14 of 19 doses administered, patients had a bowel movement within 4 hours. Three patients had documented mild gastrointestinal upset following methylnaltrexone administration. None reported a reduction of pain control or opioid withdrawal symptoms.. This case series suggests that methylnaltrexone is safe and may be effective when given subcutaneously as a 0.15 mg/kg single dose to pediatric oncology patients with opioid-induced constipation.

Topics: Adolescent; Analgesics, Opioid; Child; Child, Preschool; Constipation; Female; Humans; Male; Naltrexone; Narcotic Antagonists; Neoplasms; Pain; Quaternary Ammonium Compounds; Retrospective Studies

Methylnaltrexone has been shown to be effective for treating opioid-induced constipation (OIC) in chronic settings, but its effects on acute OIC have not been studied.. To assess safety and efficacy of subcutaneous methylnaltrexone in patients with acute OIC after orthopedic procedures.. Double-blind, randomized, parallel-group, placebo-controlled, hypothesis-generating phase 2 study.. Sixteen US hospitals and rehabilitation facilities.. Adult patients with acute OIC after orthopedic surgical procedure, expected to require opioids for at least 7 days postrandomization.. Patients received once-daily subcutaneous methylnaltrexone 12 mg or placebo for up to 4 or 7 days.. All endpoints were exploratory and included the percentage of patients achieving laxation within 2 and 4 hours of first dose and time to laxation.. Thirty-three patients received at least 1 dose of study drug (methylnaltrexone, n = 18; placebo, n = 15). Within 2 and 4 hours, significantly more patients receiving methylnaltrexone achieved laxation (2 hours: 33.3% vs 0%, P = 0.021; 4 hours: 38.9% vs 6.7%, P = 0.046) compared with placebo. Time to laxation was significantly shorter with methylnaltrexone (median = 15.8 hours) versus placebo (median = 50.9 hours), P = 0.0197. The most common adverse events related to the gastrointestinal tract. Pain scores remained stable and were similar to those of placebo, and signs and symptoms of opioid withdrawal did not emerge in patients receiving methylnaltrexone.. Methylnaltrexone was generally well tolerated and was active in inducing laxation in this study of patients experiencing acute OIC following orthopedic surgery.

Topics: Aged; Analgesics, Opioid; Constipation; Double-Blind Method; Female; Humans; Injections, Subcutaneous; Male; Middle Aged; Naltrexone; Narcotic Antagonists; Orthopedic Procedures; Pilot Projects; Quaternary Ammonium Compounds; Rehabilitation; Treatment Outcome

Methylnaltrexone, a selective peripheral acting mu-opioid receptor antagonist, alleviates the constipating effects of opioids without affecting centrally mediated analgesia.. To assess the effect of subcutaneous (SC) methylnaltrexone injection on patient-reported constipation symptoms and pain scores.. A total of 469 subjects on opioids for chronic non-malignant pain with opioid-induced constipation were randomized to methylnaltrexone SC with once daily (QD) or every other day (QOD) dosing or placebo for 4 weeks. Constipation symptoms and pain were assessed using the patient assessment of constipation-symptoms (PAC-SYM) questionnaire and a 11-point scale, respectively, at baseline, Day 14 and Day 28. Change from baseline in PAC-SYM and pain scores were compared between methylnaltrexone and placebo arms at Day 28 using analysis of covariance, with treatment group as factor and baseline score as covariate.. A majority of patients were women (60%), average age was 49 years old, and back pain (60%) was the primary pain condition. At Day 28, the methylnaltrexone SC QD group showed a significant improvement over placebo for rectal symptoms (-0.56 vs. -0.30; P < 0.05), stool symptoms (-0.76 vs. -0.43; P < 0.001) and global scores (-0.62 vs. -0.37; P < 0.001). Improvement in stool symptoms (-0.69 vs.-0.43; P < 0.05) and the global scores (-0.52 vs. -0.37; P < 0.05) were significantly greater than placebo in the methylnaltrexone QOD group. Differences in change from baseline in abdominal symptoms and pain scores between the methylnaltrexone SC QD or QOD dosing arms and placebo were not significant.. The results of our study indicate significant improvement in constipation symptoms with methylnaltrexone QD or QOD dosing compared to placebo without a significant effect on pain scores.

Topics: Analgesics, Opioid; Back Pain; Chronic Disease; Constipation; Double-Blind Method; Female; Humans; Injections, Subcutaneous; Male; Middle Aged; Naltrexone; Narcotic Antagonists; Quaternary Ammonium Compounds

Methylnaltrexone is effective for opioid-induced constipation (OIC) in advanced illness patients. This 4-week, double-blind, randomized, placebo-controlled study investigated the effect of subcutaneous methylnaltrexone on OIC in patients receiving opioids for chronic, nonmalignant pain. Patients (N = 460) received subcutaneous methylnaltrexone 12 mg once daily (QD) or every other day (alternating with placebo) compared with placebo. Assessments included bowel movement count, time of bowel movement, straining, sense of complete evacuation, Bristol Stool Form Scales, and quality of life. Within 4 hours of first dose, 34.2% of patients in both methylnaltrexone groups had rescue-free bowel movements (RFBMs) versus 9.9% on placebo (P < .001). The estimated number needed to treat was about 4. On average, 28.9% of methylnaltrexone QD and 30.2% of methylnaltrexone alternate-day dosing resulted in RFBMs within 4 hours versus 9.4% QD and 9.3% alternate-day placebo injections (both P < .001). Both methylnaltrexone groups had significantly shorter time to first RFBM (P < .001) and greater increase in number of weekly RFBMs (P < .05) versus placebo. Adverse events included abdominal pain, diarrhea, nausea, and hyperhidrosis. Bristol Stool Form Scale scores (P = .002) and sensation of complete evacuation (P < .04) were significantly superior with methylnaltrexone QD; both methylnaltrexone groups reported no or mild straining during RFBMs in the first 2 weeks (P < .02). At 4 weeks, a significantly greater improvement in patient-reported, constipation-specific quality of life was seen in the alternate-day dosing (P < .05) and QD (P < .001) groups.. We present data demonstrating that subcutaneous methylnaltrexone 12 mg given once daily (QD) or every other day provides significant relief of OIC and was generally well tolerated in patients with chronic, nonmalignant pain. These results expand on prior effectiveness observed for the treatment of OIC in advanced illness patients to a broader population.

Topics: Adult; Aged; Analgesics, Opioid; Chi-Square Distribution; Constipation; Defecation; Double-Blind Method; Female; Humans; Intention to Treat Analysis; Male; Middle Aged; Naltrexone; Narcotic Antagonists; Pain; Quaternary Ammonium Compounds; Surveys and Questionnaires; Treatment Outcome

Methylnaltrexone is a methylated form of the mu-opioid antagonist naltrexone that blocks peripheral effects of opioids without affecting centrally mediated analgesia. The authors conducted a 3-month open-label extension trial of methylnaltrexone in patients with advanced illness and opioid-induced constipation (OIC). Following completion of a 2-week double-blind (DB) trial, 82 patients with OIC who did not respond to laxatives received subcutaneous (SC) methylnaltrexone as needed for up to 3 months. Patients received 0.15 mg/kg as a first dose, adjusted to 0.3 mg/kg or 0.075 mg/kg as needed (maximum of one dose per 24 hours). Mean laxation response (rescue-free bowel movement within 4 hours) rates (DB phase, months 1, 2, 3 open-label phase) were 45.3%, 45.5%, 57.7%, and 57.3%, respectively, for patients treated with DB methylnaltrexone and 10.8%, 48.3%, 47.6%, and 52.1%, respectively, for patients treated with DB placebo. Median time to laxation among responders was 45 minutes (range 0-4 hours) for all doses. Approximately 50% of patients reported improvement in constipation distress. Patient and investigator global clinical impression of change scores also improved. There were minimal changes in pain scores and opioid withdrawal symptoms. Adverse events included abdominal pain and nausea, mostly mild or moderate in severity. SC methylnaltrexone administered PRN (as needed) for up to 3 months continued to rapidly induce laxation in advanced illness patients with OIC.

Topics: Aged; Aged, 80 and over; Analgesics, Opioid; Constipation; Dose-Response Relationship, Drug; Female; Follow-Up Studies; Humans; Injections, Subcutaneous; Male; Middle Aged; Naltrexone; Narcotic Antagonists; Quaternary Ammonium Compounds; Substance Withdrawal Syndrome; Time Factors; Treatment Outcome

Methylnaltrexone, a selective peripherally acting mu-opioid receptor antagonist, effectively treats opioid-induced constipation (OIC) in patients with advanced illness and shows efficacy in patients with chronic nonmalignant pain. The objective was to identify patients who achieved maximal treatment effect based on response to initial four methylnaltrexone doses.. A post hoc analysis of a randomized, double-blind, placebo-controlled study evaluating patients with OIC and chronic nonmalignant pain who received 12 mg subcutaneous methylnaltrexone daily for 4 weeks was performed to determine if response to the first four methylnaltrexone doses predicted overall response during the study. Patients receiving ≥8 doses were included.. Patients having ≥3 rescue-free bowel movements (RFBMs)/week; change from baseline in RFBMs/week; percentage of doses with RFBMs within 4 hours after dosing.. Of 137 patients, 58 patients (42.3%) had RFBMs after ≥2 of four doses. Among those with response to ≥2 of four doses, 81% had ≥3 RFBMs/week vs. 43% for those with response to <2 of four (P < 0.0001). Those with RFBMs after ≥2 of first four doses averaged 4.8 RFBMs/week vs. 2.0 RFBMs/week for those with <2 of four (P < 0.0001). Percentage of subsequent injections resulting in RFBMs within 4 hours was 45.9 ± 27.6 for those with response to ≥2 of four doses vs. 17.1 ± 19.1 for those with response to <2 of four (P < 0.0001). Abdominal pain was the most frequently reported adverse event.. Early response to ≥2 of first four doses of methylnaltrexone identified patients who demonstrated a particularly robust effect of treatment over the duration of use.

Topics: Adult; Analgesics, Opioid; Constipation; Double-Blind Method; Female; Humans; Injections, Subcutaneous; Male; Middle Aged; Naltrexone; Narcotic Antagonists; Placebos; Quaternary Ammonium Compounds; Treatment Outcome

Methylnaltrexone is a selective peripherally acting mu-opioid receptor antagonist that decreases the constipating effects of opioids without affecting centrally mediated analgesia. In two double-blind, placebo-controlled, Phase III studies of methylnaltrexone for opioid-induced constipation in patients with advanced illness, abdominal pain was the most common adverse event (AE) reported.. This analysis sought to further characterize the Medical Dictionary for Regulatory Activities-defined abdominal pain AEs experienced in these studies.. A post hoc analysis of verbatim descriptions was used to further assess AEs characterized as abdominal pain in both trials. Descriptive summary statistics were used to assess severity of abdominal pain, effect of abdominal pain on global pain scores, and other characteristics. Logistic regression analysis was used to determine the association of baseline characteristics with abdominal pain.. Most verbatim descriptions of abdominal pain referred to "abdominal cramps" or "cramping." Abdominal pain AEs were mostly mild to moderate in severity and did not affect patients' global evaluation of pain. The incidence of abdominal pain AEs in methylnaltrexone-treated patients was greatest after the first dose and decreased with subsequent doses. No association between abdominal pain AEs and most baseline patient characteristics was noted.. Abdominal pain AEs in methylnaltrexone-treated patients in clinical trials are usually described as "cramps" or "cramping," are mostly mild to moderate in severity, and decrease in incidence with subsequent dosing.

Topics: Abdominal Pain; Adult; Aged; Analgesics, Opioid; Colic; Constipation; Double-Blind Method; Female; Humans; Male; Middle Aged; Naltrexone; Narcotic Antagonists; Pain Measurement; Quaternary Ammonium Compounds

Methylnaltrexone, a peripherally acting mu-opioid receptor antagonist with restricted ability to cross the blood-brain barrier, reverses opioid-induced constipation (OIC) without affecting analgesia. A double-blind study in patients with advanced illness and OIC demonstrated that methylnaltrexone significantly induced laxation within four hours after the first dose compared with placebo. In this study, patients with advanced illness and OIC on stable doses of opioids and laxatives were randomized to methylnaltrexone 0.15mg/kg (n=62) or placebo (n=71) subcutaneously every other day for two weeks. Laxation was assessed daily. Constipation distress, bowel status change, pain, laxative use, and opioid withdrawal symptoms were assessed weekly using standardized scales. Additional analyses to further characterize response to methylnaltrexone revealed that among patients with a bowel movement within four hours following the first dose, the median time to response was 0.5 hours for methylnaltrexone. Response rates among methylnaltrexone-treated patients who had responded to all previous doses were 57%-100% for doses two to seven. Among methylnaltrexone-treated patients who did not respond to the first or to the first two consecutive doses, 35% and 26% responded to the second and third dose, respectively. Higher percentages of patients and clinicians rated bowel status as improved in the methylnaltrexone than the placebo group. Fewer methylnaltrexone than placebo patients reported use of common laxative types, particularly enemas, during the study. Subcutaneous methylnaltrexone promptly and predictably induced laxation, improved constipation distress, and was associated with less laxative use in patients with advanced illness and OIC.

Topics: Analgesics, Opioid; Constipation; Defecation; Double-Blind Method; Humans; Laxatives; Naltrexone; Narcotic Antagonists; Pain, Intractable; Palliative Care; Quaternary Ammonium Compounds

Constipation is a distressing side effect of opioid treatment. As a quaternary amine, methylnaltrexone, a mu-opioid-receptor antagonist, has restricted ability to cross the blood-brain barrier. We investigated the safety and efficacy of subcutaneous methylnaltrexone for treating opioid-induced constipation in patients with advanced illness.. A total of 133 patients who had received opioids for 2 or more weeks and who had received stable doses of opioids and laxatives for 3 or more days without relief of opioid-induced constipation were randomly assigned to receive subcutaneous methylnaltrexone (at a dose of 0.15 mg per kilogram of body weight) or placebo every other day for 2 weeks. Coprimary outcomes were laxation (defecation) within 4 hours after the first dose of the study drug and laxation within 4 hours after two or more of the first four doses. Patients who completed this phase were eligible to enter a 3-month, open-label extension trial.. In the methylnaltrexone group, 48% of patients had laxation within 4 hours after the first study dose, as compared with 15% in the placebo group, and 52% had laxation without the use of a rescue laxative within 4 hours after two or more of the first four doses, as compared with 8% in the placebo group (P<0.001 for both comparisons). The response rate remained consistent throughout the extension trial. The median time to laxation was significantly shorter in the methylnaltrexone group than in the placebo group. Evidence of withdrawal mediated by central nervous system opioid receptors or changes in pain scores was not observed. Abdominal pain and flatulence were the most common adverse events.. Subcutaneous methylnaltrexone rapidly induced laxation in patients with advanced illness and opioid-induced constipation. Treatment did not appear to affect central analgesia or precipitate opioid withdrawal. (Clinical Trials.gov number, NCT00402038 [ClinicalTrials.gov].).

Topics: Adult; Aged; Aged, 80 and over; Analgesics, Opioid; Constipation; Defecation; Double-Blind Method; Female; Humans; Injections, Subcutaneous; Laxatives; Logistic Models; Male; Middle Aged; Naltrexone; Narcotic Antagonists; Quaternary Ammonium Compounds; Terminally Ill

Constipation is the most common chronic adverse effect of opioid pain medications in patients who require long-term opioid administration, such as patients with advanced cancer, but conventional measures for ameliorating constipation often are insufficient.. To evaluate the efficacy of methylnaltrexone, the first peripheral opioid receptor antagonist, in treating chronic methadone-induced constipation.. Double-blind, randomized, placebo-controlled trial conducted between May 1997 and December 1998.. Clinical research center of a university hospital.. Twenty-two subjects (9 men and 13 women; mean [SD] age, 43.2 [5.5] years) enrolled in a methadone maintenance program and having methadone-induced constipation.. Laxation response, oral-cecal transit time, and central opioid withdrawal symptoms were compared between the 2 groups.. The 11 subjects in the placebo group showed no laxation response, and all 11 subjects in the intervention group had laxation response after intravenous methylnaltrexone administration (P<.001). The oral-cecal transit times at baseline for subjects in the methylnaltrexone and placebo groups averaged 132.3 and 126.8 minutes, respectively. The average (SD) change in the methylnaltrexone-treated group was -77.7 (37.2) minutes, significantly greater than the average change in the placebo group (-1.4 [12.0] minutes; P<.001). No opioid withdrawal was observed in any subject, and no significant adverse effects were reported by the subjects during the study.. Our data demonstrate that intravenous methylnaltrexone can induce laxation and reverse slowing of oral cecal-transit time in subjects taking high opioid dosages. Low-dosage methylnaltrexone may have clinical utility in managing opioid-induced constipation.

Topics: Adult; Analgesics, Opioid; Constipation; Double-Blind Method; Female; Gastrointestinal Transit; Humans; Male; Methadone; Naltrexone; Narcotic Antagonists; Quaternary Ammonium Compounds; Statistics, Nonparametric; Substance Withdrawal Syndrome

Topics: Administration, Oral; Adult; Analgesics, Opioid; Constipation; Humans; Methadone; Naltrexone; Narcotic Antagonists; Narcotics; Quaternary Ammonium Compounds; Single-Blind Method

Opioid-induced constipation (OIC) may occur in up to 81% of critically ill patients and can lead to many complications. Opioid antagonists are a reasonable approach and may be used for managing OIC.. The purpose of this study was to assess the efficacy of enteral naloxone (NLX) versus subcutaneous methylnaltrexone (MNTX) for the management of OIC in critically ill patients.. A retrospective analysis was conducted on adult patients who received NLX or MNTX and a continuous opioid infusion for at least 48 hours. The primary end point was time to resolution of constipation, defined as hours to first bowel movement (BM) after the first dose of an opioid antagonist. Reversal of analgesia was assessed by comparing the total number of morphine milligram equivalents (MME) 24 hours preopioid and postopioid antagonist administration. Univariate and multivariate analyses were conducted to assess treatment response within 48 hours.. The time to first BM was shorter with enteral NLX. Both NLX and MNTX appear to be effective for the management of OIC without causing reversal of analgesia. Future controlled, prospective trials comparing these agents are warranted.

Topics: Adult; Analgesics, Opioid; Constipation; Critical Illness; Humans; Naloxone; Naltrexone; Narcotic Antagonists; Opioid-Induced Constipation; Pain; Prospective Studies; Quaternary Ammonium Compounds; Retrospective Studies

Peripherally acting μ-opioid receptor antagonists (PAMORAs) are indicated to treat laxative-refractory opioid-induced constipation (OIC). While several PAMORAs exist, no head-to-head comparative data are available. This study evaluated the efficacy, safety, and cost of oral naloxegol vs subcutaneous methylnaltrexone for OIC in the hospital.. In this multicenter retrospective chart review, patients who received oral naloxegol or subcutaneous methylnaltrexone as an inpatient were included if they were at least 18 years old, were still admitted to the hospital 48 hours after the first PAMORA dose, and either had an outpatient opioid prescription or received at least 30 morphine milligram equivalents in the 24 hours before the first PAMORA dose. The primary outcome was achievement of a bowel movement (BM) within 48 hours of the first dose. Secondary outcomes included a BM in 24 hours, time to the first BM, antimotility agent use, PAMORA cost per patient, and use of a second PAMORA due to failure of the first agent.. A total of 330 patients were included with 2:1 allocation (220 patients receiving methylnaltrexone vs 110 patients receiving naloxegol). Baseline characteristics were similar between the groups, except for body mass index and weight. Naloxegol met a prespecified noninferiority margin of 15% in production of a BM within 48 hours (risk difference, -4.6%; 90% confidence interval, -13.6% to 4.5%; P = 0.028). Achievement of a BM within 24 hours and time to first BM were also noninferior. Antimotility agent use was higher with naloxegol, naloxegol cost $193.16 less per patient, and 2 patients switched from naloxegol to methylnaltrexone.. Oral naloxegol may be an effective, cost-efficient alternative to subcutaneous methylnaltrexone for treatment of OIC in the hospital setting.

Topics: Adolescent; Analgesics, Opioid; Constipation; Hospitals; Humans; Narcotic Antagonists; Opioid-Induced Constipation; Retrospective Studies

Opioid-induced constipation (OIC) is a common adverse effect of opioid analgesics. Peripherally acting μ opioid receptor antagonists (PAMORAs) can be applied in the treatment of OIC without compromising the analgesic effects. NAP, a 6β-N-4-pyridyl-substituted naltrexamine derivative, was previously identified as a potent and selective MOR antagonist mainly acting peripherally but with some CNS effects. Herein, we introduced a highly polar aromatic moiety, for example, a pyrazolyl or imidazolyl ring to decrease CNS MPO scores in order to reduce passive BBB permeability. Four compounds

Topics: Analgesics, Opioid; Constipation; Humans; Ligands; Naltrexone; Narcotic Antagonists; Opioid-Induced Constipation; Receptors, Opioid, mu

Pain management with opioids is often limited by medication side effects. One of the most common and distressing side effects is opioid-induced constipation (OIC), a syndrome that is now getting significant national attention. We report the case of an opioid-dependent 56-year-old man who underwent lumbar decompression for spinal stenosis. Postoperatively, he developed OIC and Ogilvie syndrome, then following treatment with methylnaltrexone experienced an acute bowel perforation. We briefly review the recommended management of OIC as well as indications and contraindications of methylnaltrexone and similar new medications.

Topics: Analgesics, Opioid; Colonic Pseudo-Obstruction; Constipation; Decompression, Surgical; Humans; Hydromorphone; Intestinal Perforation; Low Back Pain; Male; Methadone; Middle Aged; Naltrexone; Narcotic Antagonists; Opioid-Related Disorders; Oxycodone; Postoperative Complications; Quaternary Ammonium Compounds; Spinal Stenosis

Opioids are prescribed in over 40% of patients with advanced cancer, but side effects occur frequently. In this study we evaluated the development and treatment of opioid induced constipation (OIC), and OIC resolving effect of methylnaltrexone for different opioid subtypes in daily clinical practice.. Patients with cancer using opioids were included in a retrospective chart analysis. Baseline characteristics, data on opioid use, laxative use, and OIC were collected. Patients with OIC who were prescribed methylnaltrexone, were included in a prospective observational trial (NCT01955213).. Thirty-nine of 327 patients (pts) with cancer who were treated with opioids suffered from OIC (overall prevalence 12%; 95%-CI: 8-15%). The prevalence of OIC was similar in patients treated with oxycodone or fentanyl (12 of 81 pts. vs. 18 of 110 pts., RR 0.9; 95%CI 0.4-2.0). The morphine equivalent daily dose did not significantly differ between opioid subtypes (fentanyl 89 mg (IQR 60-180) vs. oxycodone 40 mg (40-80), P = 0.231). Twenty-two individual patients (7%) were admitted for OIC. Most effective laxatives in admitted patients were enemas, methylnaltrexone, or 4-l polyethylene-glycol solution. In the prospective observational study, the effect of methylnaltrexone could be evaluated in 23 patients. Eleven patients achieved the primary endpoint of ≥2 laxation responses out of the first four doses methylnaltrexone, independent of opioid subtype.. OIC is a burdensome clinical problem independent of opioid subtype. Timely intensification of prophylactic laxative treatment, especially when opioid doses increase, may help to prevent OIC. Clinically overt OIC requires a more intensive laxative regimen with for example methylnaltrexone.. NCT01955213 .

Topics: Aged; Analgesics, Opioid; Constipation; Female; Fentanyl; Humans; Laxatives; Male; Middle Aged; Naltrexone; Narcotic Antagonists; Neoplasms; Oxycodone; Pain Management; Prospective Studies; Quaternary Ammonium Compounds; Retrospective Studies; Surveys and Questionnaires

Opioid-induced constipation (OIC) has become increasingly prevalent with the rise of prescription opioid use and can significantly impact quality of life, especially in patients with advanced illness. Methylnaltrexone has proven effective in treating cancer patients with OIC who have not responded adequately to conventional laxative therapy, though use is relatively contraindicated in those with peritoneal carcinomatosis due to theoretical risk and reported cases of perforation. The aim of this study was to evaluate the safety of methylnaltrexone in patients with carcinomatosis. We performed a retrospective review of 3058 pediatric and adult patients who received methylnaltrexone at Memorial Sloan Kettering Cancer Center from 2009-2016. Data collected included age, cancer diagnosis, history of abdominal surgery, prior radiation therapy, evidence of peritoneal carcinomatosis, and complications. Charts were reviewed for any complications at 24 hours, 72 hours, and one week following drug administration, as well as at present. We identified 3058 patients (median age 56, range 1-95) who received a total of 3995 doses of methylnaltrexone. Three hundred thirty three (median age 55, range 4-88) had peritoneal carcinomatosis. The most common primary malignancies included pancreatic (17.7%), ovarian (13.5%), colon (7.2%), and lung (6.6%). 228/333 (68.4%) had a history of abdominal surgery and 85/333 (25.5%) underwent prior radiation therapy. Three patients had adverse outcomes or complications, with only one (0.3%) thought to be related to methylnaltrexone use. To our knowledge, this is the largest study to evaluate the outcomes of patients with carcinomatosis receiving methylnaltrexone and the first to include pediatric patients. We found one perforation attributed to methylnaltrexone. Methylnaltrexone should be considered for treatment of refractory OIC in cancer patients with peritoneal carcinomatosis due to low risk of complications.

Topics: Adolescent; Adult; Aged; Aged, 80 and over; Analgesics, Opioid; Child; Child, Preschool; Constipation; Female; Humans; Infant; Male; Middle Aged; Naltrexone; Peritoneal Neoplasms; Quaternary Ammonium Compounds; Retrospective Studies; Treatment Outcome; Young Adult

Two 6β- N-heterocyclic naltrexamine derivatives, NAP and NMP, have been identified as peripherally selective mu opioid receptor (MOR) antagonists. To further enhance the peripheral selectivity of both compounds, the 17-amino group and the nitrogen atom of the pyridine ring in both NAP and NMP were methylated to obtain dMNAP and dMNMP, respectively. Compared with NAP and NMP, the binding affinities of dMNAP and dMNMP shifted to MOR and KOR (kappa opioid receptor) dual selective and they acted as moderate efficacy partial agonists. The results from radioligand binding studies were further confirmed by molecular docking studies. In vivo studies demonstrated that dMNAP and dMNMP did not produce antinociception nor did they antagonize morphine's antinociceptive activity, indicating that these compounds did not act on the central nervous system. Meanwhile, both dMNAP and dMNMP significantly slowed down fecal excretion, which indicated that they were peripherally acting opioid receptor agonists. All together, these results suggested that dMNAP and dMNMP acted as peripheral mu/kappa opioid receptor modulators and may be applicable in the treatment of diarrhea in patients with bowel dysfunction.

Topics: Analgesics, Opioid; Animals; CHO Cells; Constipation; Cricetulus; Diarrhea; Drug Partial Agonism; Gastrointestinal Agents; Gastrointestinal Transit; Imidazoles; Methylation; Mice; Molecular Docking Simulation; Morphine; Naltrexone; Narcotic Antagonists; Nociception; Phenylalanine; Quaternary Ammonium Compounds; Radioligand Assay; Receptors, Opioid, delta; Receptors, Opioid, kappa; Receptors, Opioid, mu

Opioid-induced constipation (OIC) is common in critically ill patients; it leads to complications that can increase hospital stay and, rarely, bowel perforation. Opioid antagonists are considered a logical approach to treat OIC; however, the agent of choice has yet to be determined.. To assess the effectiveness and safety of enteral naloxone (NTX) versus subcutaneous methylnaltrexone (MNTX) for the treatment of OIC in the medical intensive care unit.. This retrospective review evaluated patients who received fentanyl continuous infusions for at least 72 hours and were initiated on NTX or MNTX. Active colitis, mechanical gastrointestinal obstruction, and inability to receive NTX orally were exclusion criteria. The primary outcome was time to first bowel movement (BM). Secondary outcomes included total number of BMs within 48 hours, opioid requirements after NTX or MNTX, and change in any of the following after the opioid antagonist: heart rates, mean arterial pressures, and level of sedation. A post hoc subgroup analysis of patients on vasopressors was conducted.. Baseline characteristics were similar between patients receiving NTX (n = 52) and MNTX (n = 48), except the MNTX group required a higher median norepinephrine dose (0.22 vs 0.1 µg/kg/min, P = 0.001). The median times to first BM for NTX and MNTX were 30 and 24 hours ( P = 0.165). There was no difference in the primary outcomes for patients on vasopressors. Both groups did not require additional fentanyl equivalents, as evidenced by stable vitals and opioid requirements during treatment.. Both agents appear to be effective and safe for the treatment of OIC; however, future controlled prospective trials are warranted.

Topics: Adult; Analgesics, Opioid; Constipation; Critical Illness; Electronic Health Records; Female; Fentanyl; Heart Rate; Humans; Intensive Care Units; Male; Middle Aged; Naltrexone; Narcotic Antagonists; Prospective Studies; Quaternary Ammonium Compounds; Retrospective Studies

Topics: Abdominal Pain; Analgesics, Opioid; Child; Constipation; Critical Illness; Defecation; Humans; Infant; Laxatives; Male; Morphine; Naltrexone; Narcotic Antagonists; Quaternary Ammonium Compounds; Treatment Outcome

Topics: Analgesics, Opioid; Constipation; Humans; Naltrexone; Quaternary Ammonium Compounds; Terminal Care

Opioid-induced constipation (OIC) is common among children and adolescents and young adults (AYA) with progressive incurable cancer. Although methylnaltrexone is a successful treatment for OIC in adult cancer patients, no case series has established its safety and efficacy in pediatric cancer patients.. The aim of the study was to describe the safety and efficacy of methylnaltrexone use for OIC in children and AYA with progressive incurable cancer at the end of life in the inpatient and outpatient settings.. We conducted a retrospective review of medical records of children and AYA with progressive incurable cancer who received methylnaltrexone at our institution from May 2008 to June 2013. Pharmacy data were reviewed for each patient and a chart review was performed for documentation of laxation and side effects.. Of the 9 patients (age range: 17 months to 21 years) with progressive incurable cancer who developed OIC, 7 (78%) had laxation after methylnaltrexone administration (0.15 mg/kg/dose). Of these 7 patients, 5 (71%) had laxation with the first dose, and 5 (71%) who responded had a continued response to repeated doses. The longest a patient regularly received methylnaltrexone was 9 months. Of 5 patients with intraabdominal disease, 4 (80%) had laxation. There were no negative side effects in any of the patients. Also, there was no increase in pain either qualitatively or by pain score.. Methylnaltrexone appears to be safe and efficacious in treating OIC in children and AYA with progressive incurable cancer. Methylnaltrexone was tolerated in both the inpatient and outpatient settings and with repeated dosing.

Topics: Adolescent; Analgesics, Opioid; Child; Child, Preschool; Constipation; Double-Blind Method; Female; Humans; Infant; Male; Medical Audit; Naltrexone; Narcotic Antagonists; Neoplasms; Quaternary Ammonium Compounds; Retrospective Studies; Terminally Ill; Young Adult

Topics: Analgesics, Opioid; Constipation; Humans; Morphinans; Naloxone; Naltrexone; Narcotic Antagonists; Polyethylene Glycols; Quaternary Ammonium Compounds

Topics: Adult; Analgesics, Opioid; Chronic Pain; Constipation; Drug Approval; Humans; Morphinans; Naltrexone; Narcotic Antagonists; Polyethylene Glycols; Quaternary Ammonium Compounds; United States; United States Food and Drug Administration

Off-label uses of the peripheral μ-opioid receptor antagonists alvimopan and methylnaltrexone are reviewed.. Alvimopan is approved by the Food and Drug Administration (FDA) for postoperative ileus after surgeries that include partial bowel resection with primary anastomosis, while methylnaltrexone is approved for the treatment of opioid-induced constipation (OIC) in patients with advanced illness who are receiving palliative care. Literature describing the off-label use of alvimopan in the treatment of OIC and of methylnaltrexone in postoperative ileus was reviewed and included retrospective studies and prospective Phase II-IV trials. Randomized controlled trials did not demonstrate consistent benefit of alvimopan in OIC nor of methylnaltrexone in postoperative ileus. A greater proportion of patients receiving alvimopan for OIC experienced severe adverse cardiovascular events, leading to a risk evaluation and mitigation strategy and discontinuation of its study in this condition. Data are limited and unreplicated for the off-label use of alvimopan for postoperative ileus in patients undergoing abdominal hysterectomy. Individual studies suggest benefit with methylnaltrexone for OIC in unlabeled populations, including patients with non-cancer-related pain, opioid dependence, opioid sedation, and opioid use after orthopedic surgery; however, confirmatory evaluations have not been performed.. Trials of alvimopan in the FDA-approved use of methylnaltrexone (OIC) indicate potentially serious cardiovascular safety concerns and conflicting findings of efficacy. Similarly, trials of methylnaltrexone in the FDA-approved use of alvimopan (postoperative ileus) consistently showed no benefit. Evaluations of both drugs in their labeled conditions in populations not endorsed in their product labeling have been limited and largely unreplicated.

Topics: Analgesics, Opioid; Constipation; Gastrointestinal Agents; Humans; Ileus; Naltrexone; Narcotic Antagonists; Off-Label Use; Piperidines; Postoperative Complications; Quaternary Ammonium Compounds

Opioid-induced constipation is commonly seen in pediatrics, especially at the end of life. As patients clinically decline, constipation often leads to increased pain and distress, while its enteral treatment becomes more challenging.. There is little information about the safety and use of methylnaltrexone in children. We present the case of a 17-month-old girl with progressive leukemia who was at the end of her life and whose severe opioid-induced constipation and rectal prolapse was successfully treated with the μ-opioid-receptor antagonist methylnaltrexone. We selected a lower dose based on our lack of experience with methylnaltrexone in this age group and concern for potential complications given her rectal prolapse.. Opioid-induced constipation, abdominal distention, and rectal prolapse caused our patient's most distressing symptoms, even in the context of advanced cancer. A single dose of subcutaneous methylnaltrexone (0.12 mg/kg) resolved her constipation and rectal prolapse within one hour. Although evidence is limited, the drug has successfully been used in pediatric patients with no reported side effects to date. We recommend its use earlier in the course of severe opioid-induced constipation in children unable to tolerate an oral laxation regimen. Prospective research is needed to establish the parameters for use of this effective agent in children who cannot tolerate other regimens.

Topics: Analgesics, Opioid; Constipation; Female; Humans; Infant; Leukemia, Myeloid, Acute; Naltrexone; Narcotic Antagonists; Palliative Care; Quaternary Ammonium Compounds; Rectal Prolapse

Opioids are potent analgesics for treating moderate to severe pain, but their use is associated with a number of adverse effects, especially opioid-induced constipation (OIC). If the centrally mediated analgesia of opioids could be separated from their peripherally mediated gastrointestinal effects, by a peripherally acting opioid receptor antagonist, opioid-induced bowel dysfunction could be prevented or reversed. There has been considerable interest in peripherally acting opioid antagonists or other compounds to treat OIC. Subcutaneous methylnaltrexone is the first approved therapeutic agent for treatment of OIC, and studies have been conducted using the oral formulation. This editorial contains a brief overview of other selected compounds to treat OIC. Other potential uses of peripherally acting opioid antagonist in clinical practice are also discussed.

Topics: Analgesics, Opioid; Clinical Trials, Phase III as Topic; Constipation; Humans; Naltrexone; Narcotic Antagonists; Quaternary Ammonium Compounds; Receptors, Opioid, mu

Topics: Aged; Constipation; Female; Humans; Naltrexone; Narcotic Antagonists; Palliative Care; Quaternary Ammonium Compounds; Vomiting

Topics: Analgesics, Opioid; Constipation; Humans; Naltrexone; Narcotic Antagonists; Quaternary Ammonium Compounds

Disturbed bowel habits are very common in palliative care patients, most commonly thought to be due to opioid use. The peripheral opioid-antagonist methylnaltrexone has been subsidised in Australia to ensure that palliative care patients have timely and equitable access to this medication. The aim of this paper is to describe the use of methylnaltrexone in the first year after it was subsidised for palliative care, in particular focusing on the actual use of this medication compared with predicted need.. The predicted need for methylnaltrexone was calculated using an epidemiological approach based on data collected by the Australian Institute of Health and Welfare to determine the number of Australian deaths annually. A single source of data was used to determine the number of patients who die while under the care of palliative services in Australia (National Census of Palliative Care Services, 1999). These figures allowed the number of people likely to be receiving opioids to be estimated and therefore the number who could potentially benefit from methylnaltrexone.. The number of patients who might benefit was calculated to be 5000, which contrasts with the 261 actual prescriptions written for methylnaltrexone. Even more striking was the disparity between initial prescriptions and the 93 requests for ongoing use.. These data highlight much lower use of methylnaltrexone than predicted and raise a number of questions including the fact that the palliative care literature emphasises opioids as the dominant cause of constipation in palliative care patients given little ongoing use of methylnaltrexone.

Topics: Analgesics, Opioid; Australia; Constipation; Humans; Naltrexone; Narcotic Antagonists; Needs Assessment; Palliative Care; Prescriptions; Quaternary Ammonium Compounds

Methylnaltrexone, a peripheral opioid μ-receptor antagonist is licensed for subcutaneous administration for the treatment of severe opioid-induced constipation in adults. We describe the use of intravenous methylnaltrexone in a 3-year-old boy receiving a subcutaneous diamorphine infusion for palliation from widely metastatic alveolar rhabdomyosarcoma. The patient, who had not opened his bowels for 3 weeks despite use of regular conventional laxatives, was given a 150 mcg/kg dose via indwelling central venous catheter. Constipation was relieved within minutes of the injection. There were no side effects noted during or following injection, and no clinically apparent reduction in analgesia. Intravenous methylnaltrexone may provide a valuable additional treatment option in paediatric palliative care, especially for those with an oncological diagnosis, the majority of whom will have indwelling central venous access devices.

Topics: Administration, Intravenous; Analgesics, Opioid; Child, Preschool; Constipation; Heroin; Humans; Male; Naltrexone; Narcotic Antagonists; Palliative Care; Quaternary Ammonium Compounds

Opioids are major contributing factors to the problem of constipation in palliative care. Whilst this is without doubt, it remains unclear how much other factors also contribute to the problem. The aim of this audit is to review what other contributing factors are present when methylnaltrexone, the peripheral opioid antagonist is prescribed for constipation. The medical records of people prescribed methylnaltrexone over a four-month period were reviewed to examine certain characteristics of people including the whether the reason for constipation was charted, whether other factors that could contribute to constipation were considered and the effectiveness of methylnaltrexone. Over the study period, 10 people received methylnaltrexone, only 4 of whom had a bowel action less than 24 hours after administration with 3 not having any bowel actions reported 6 days after administration. Whilst all were receiving opioids, the opioids doses were in the moderate range (61-200 mg morphine equivalent). However, all had other factors that could contribute to constipation including impaired functional status and medications with anti-cholinergic effects (mean anti-cholinergic load 4.5). In conclusion, methylnaltrexone is targeted treatment for the management of opioid-induced constipation. However, there is a percentage of people who fail to respond. The impact of other factors on the problem of constipation requires greater clarification.

Topics: Aged; Analgesics, Opioid; Constipation; Female; Humans; Laxatives; Male; Medical Records; Middle Aged; Naltrexone; Narcotic Antagonists; Neoplasms; New South Wales; Outcome Assessment, Health Care; Palliative Care; Quaternary Ammonium Compounds; Risk Factors

Opioid-induced constipation persists as a challenge in the management of chronic pain treated with opioid therapy. Multiple opioid antagonists have been applied in attempt to combat the gastrointestinal side effects of opioid analgesia, however their lipid-soluble nature allows passage into the central nervous system and consequent antagonism of centrally mediated analgesia. In contrast, methylnaltrexone offers the advantage of peripheral receptor-specific opioid antagonism due to chemical alterations conferring greater polarity and less lipid solubility. We present use of enteral methylnatrexone to treat severe opioid-induced constipation in a young boy who had failed treatment with the non-specific opioid antagonist, naloxone. This case reports describes the safe transition from enteral naloxone to enteral methylnaltrexone and discusses the potential risk of relative opioid toxicity during the transition.. Though methylnaltrexone has approved for subcutaneous use, the characteristics of the patient s disease required enteral administration which had not been described in pediatric dosing. Based on conservative extrapolation of data from adult dosing, a methylnaltrexone dosing regimen was selected and the naloxone was weaned over two days in an effort to avoid a relative opioid overdose.. The patient was successfully transitioned to methylnaltrexone from naloxone over two days. He did experience increased sedation during this time however no severe respiratory depression occurred due to the cessation of chronic central opioid antagonism causing a relative opioid toxicity. Following the institution of methylnaltrexone, his opioid requirement significantly decreased and his gastrointestinal symptoms improved.. Our case report demonstrates safe transition from enteral naloxone to enteral methylnaltrexone in a pediatric patient, avoiding the serious consequences of relative opioid toxicity. This patient experienced significant improvement of opioid-induced constipation and reduction in opioid requirements and it is possible that other patients would benefit as well. The role of enteral methylnaltrexone deserves further investigation.

Topics: Analgesics, Opioid; Child, Preschool; Chronic Pain; Constipation; Humans; Male; Naltrexone; Narcotic Antagonists; Pediatrics; Quaternary Ammonium Compounds

Gastrointestinal dysmotility and constipation are common problems in critical care patients. The majority of critical care patients are treated with opioids, which inhibit gastrointestinal (GI) motility and lead to adverse outcomes. We reasoned that methylnaltrexone (MNTX), a peripheral opioid antagonist approved for the treatment of opioid-induced constipation in patients with advanced illness receiving palliative care when response to laxative therapy has not been sufficient, could improve GI function in critically ill patients. The present study included all patients in our intensive care unit who required rescue medication for GI stasis during the 10-week period from September 1 to November 15, 2009. We compared conventional rescue therapy with subcutaneous MNTX. We performed a retrospective chart review of the 88 nonsurgical critical care patients receiving fentanyl infusions, 15 (17%) of whom met the criteria of absence of laxation within 72 hours of intensive care unit admission despite treatment with senna and sodium docusate. Eight of these 15 patients subsequently received conventional rescue therapy (combination of sodium picosulfate [5 mg] and 2 glycerin suppositories [4-g mold]), and 7 patients received MNTX (subcutaneous injection, 0.15 mg/kg). Laxation occurred within 24 hours in 6 of the 7 MNTX patients (86%) but in none of the 8 patients receiving conventional rescue therapy (P=.001). The median difference in time to laxation between the 2 groups was 3.5 days (P<.001). Although not statistically significant, all 7 patients treated with MNTX, but only 4 of 8 (50%) who received conventional rescue therapy, progressed to full target enteral feeding (P=.08). Intensive care unit mortality was 2 of 7 MNTX patients (29%) vs 4 of 8 (50%) in the standard therapy group (P=.61). We hypothesize that MNTX may play an important role in restoration of bowel function in critically ill patients.

Topics: Aged; Analgesics, Opioid; Constipation; Critical Care; Female; Gastrointestinal Motility; Humans; Laxatives; Male; Middle Aged; Naltrexone; Narcotic Antagonists; Quaternary Ammonium Compounds; Retrospective Studies; Statistics, Nonparametric

The therapeutic action of opioid analgesics is compromised by peripheral adverse effects among which opioid-induced constipation (OIC) is the most disabling, with a prevalence reported to vary between 15 and 90 %. Although OIC is usually treated with laxatives, there is insufficient clinical evidence that laxatives are efficacious in this indication. In contrast, there is ample evidence from double- blind, randomized and placebo-controlled trials that peripheral opioid receptor antagonists (PORAs) counteract OIC. This specific treatment modality is currently based on subcutaneous methylnaltrexone for the interruption of OIC in patients with advanced illness, and a fixed combination of oral prolonged-release naloxone with prolonged-release oxycodone for the prevention of OIC in the treatment of non-cancer and cancer pain. Both drugs counteract OIC while the analgesic effect of opioids remains unabated. The clinical studies show that more than 50 % of the patients with constipation under opioid therapy may benefit from the use of PORAs, while PORA-resistant patients are likely to suffer from non-opioid-induced constipation, the prevalence of which increases with age. While the addition of naloxone to oxycodone seems to act by preventing OIC, the intermittent dosing of methylnaltrexone every other day seems to stimulate defaecation by provoking an intestinal withdrawal response. The availability of PORAs provides a novel opportunity to specifically control OIC and other peripheral adverse effects of opioid analgesics (e.g., urinary retention and pruritus). The continuous dosing of a PORA has the advantage of few adverse effects, while intermittent dosing of a PORA can be associated with abdominal cramp-like pain.

Topics: Age Factors; Analgesics, Opioid; Constipation; Defecation; Drug Combinations; Gastrointestinal Tract; Humans; Laxatives; Naloxone; Naltrexone; Narcotic Antagonists; Pain; Predictive Value of Tests; Prevalence; Quaternary Ammonium Compounds; Receptors, Opioid; Risk Factors

Topics: Analgesics, Opioid; Brain Neoplasms; Child; Constipation; Female; Humans; Morphine; Naltrexone; Narcotic Antagonists; Neuroblastoma; Pain; Quaternary Ammonium Compounds

Topics: Analgesics, Opioid; Australia; Constipation; Drug Utilization; Humans; Laxatives; Naltrexone; Narcotic Antagonists; Palliative Care; Quaternary Ammonium Compounds

When laxative regimens have failed, methylnaltrexone may be indicated for the relief of opioid-induced constipation (OIC) in patients with advanced illness receiving palliative care.. A cost-benefit analysis (CBA), based on a willingness-to-pay (WTP) approach, was performed to determine if methylnaltrexone should be added to the formulary list of drugs being reimbursed by third-party payers in Canada for the treatment of cancer patients in palliative care suffering from OIC.. The WTP study had two components: a decision board explaining treatment options (Component A) and a questionnaire to measure individual WTP using a bidding game approach (Component B). Component A had two options: Option 1 (laxatives only) and Option 2 (laxatives+methylnaltrexone injection). Only participants choosing Option 2 were invited to complete Component B. The results of the WTP survey were then incorporated into a CBA. Within a hypothetical cohort, additional monthly premiums that individuals were willing to pay for methylnaltrexone were compared with the monthly costs to the insurer for providing methylnaltrexone to all patients who would potentially be using it.. Four hundred one Canadians, of age 18 years and older, were surveyed and yielded a WTP in additional monthly insurance premiums of Canadian dollar (CAD) $8.65 (95% confidence interval: CAD$6.17-CAD$11.13). The CBA resulted in additional CAD$89,307 with a cost of CAD$139,840 and benefits of CAD$229,147. A set of 10,000 Monte Carlo simulations resulted in average CBA savings of CAD$145,011 with a 99.86% probability of dominance.. The present CBA provides pharmacoeconomic evidence for the adoption of methylnaltrexone for treating OIC in terminally ill cancer patients.

Topics: Adolescent; Adult; Age Distribution; Analgesics, Opioid; Constipation; Consumer Behavior; Cost of Illness; Cost-Benefit Analysis; Female; Health Care Costs; Humans; Male; Middle Aged; Naltrexone; Narcotic Antagonists; Neoplasms; Ontario; Pain; Palliative Care; Patient Acceptance of Health Care; Quaternary Ammonium Compounds; Sex Distribution; Socioeconomic Factors; Treatment Outcome; Young Adult

Topics: Analgesics, Opioid; Constipation; Humans; Naltrexone; Narcotic Antagonists; Quaternary Ammonium Compounds

Topics: Analgesics, Opioid; Constipation; Humans; Laxatives; Naltrexone; Narcotic Antagonists; Pain; Palliative Care; Quaternary Ammonium Compounds

Opioid-induced constipation is a common adverse event in patients with advanced illness and has a significant negative impact on patients' quality of life and costs.. To examine the cost-effectiveness of treating opioid-induced constipation with methylnaltrexone bromide (MNTX) plus standard care compared with standard care alone in patients with advanced illness who receive long-term opioid therapy from a third-party payer perspective in the Netherlands.. A decision-analytical model was created in which advanced-illness patients with constipation were treated with MNTX plus standard care or standard care alone. Clinical efficacy in terms of percentage of patients with rescue-free laxation and time to rescue-free laxation were obtained from a randomized, controlled clinical study. Resource use, costs, utilities and mortality were obtained from published literature and supplemented with data from clinical experts.. Treatment with MNTX plus standard care results in more days without constipation symptoms. Cost of MNTX was mostly offset by reduction in other constipation-related costs. Thus, treating with MNTX plus standard care is cost-effective, with an incremental cost per QALY of 40,865 euro. Results were robust to changes in all parameters.. Although using MNTX may increase total costs, MNTX plus standard care is cost-effective in treating advanced-illness patients with opioid-induced constipation.

Topics: Adolescent; Adult; Aged; Analgesics, Opioid; Constipation; Cost-Benefit Analysis; Humans; Laxatives; Middle Aged; Naltrexone; Narcotic Antagonists; Quality-Adjusted Life Years; Quaternary Ammonium Compounds; Terminally Ill; Young Adult

Topics: Alprostadil; Analgesics, Opioid; Constipation; Delayed-Action Preparations; Drug Therapy, Combination; Humans; Laxatives; Lubiprostone; Naloxone; Naltrexone; Narcotic Antagonists; Oxycodone; Quaternary Ammonium Compounds

Topics: Analgesics, Opioid; Constipation; Humans; Naltrexone; Narcotic Antagonists; Quaternary Ammonium Compounds

Topics: Analgesics, Opioid; Constipation; Humans; Injections, Subcutaneous; Naltrexone; Narcotic Antagonists; Quality of Life; Quaternary Ammonium Compounds

We observed a patient with incomplete, cervical paraplegia and opioid-induced constipation who developed a resistance to laxatives after 15 years of treatment. The constipation-induced reduction in the patient's quality of life was improved using 12 mg methylnaltrexone, a peripheral mu-opioid receptor antagonist, administered subcutaneously twice a week.

Topics: Aged; Cervical Vertebrae; Constipation; Fecal Impaction; Humans; Injections, Subcutaneous; Male; Naltrexone; Narcotic Antagonists; Narcotics; Paraplegia; Postoperative Complications; Quaternary Ammonium Compounds; Spinal Cord Compression

Topics: Analgesics, Opioid; Clinical Trials as Topic; Constipation; Double-Blind Method; Drug Approval; Europe; Humans; Naltrexone; Narcotic Antagonists; Quaternary Ammonium Compounds; Terminally Ill

Opioid-induced constipation is common in palliative care and causes considerable distress to patients taking opioids. Opioid-induced constipation can be difficult to manage with conventional laxatives, often requiring invasive rectal interventions. A unique bowel intervention linked specifically to opioid-induced constipation in the form of a subcutaneous injection is now available for the management of opioid-induced constipation. This article will examine all aspects of opioid-induced constipation with particular reference to this new management option, methylnaltrexone bromide (Relistor).

Topics: Aged, 80 and over; Algorithms; Analgesics, Opioid; Causality; Constipation; Cost of Illness; Decision Trees; Female; Humans; Injections, Subcutaneous; Laxatives; Naltrexone; Narcotic Antagonists; Nursing Assessment; Palliative Care; Quaternary Ammonium Compounds

Topics: Analgesics, Opioid; Constipation; Humans; Laxatives; Naltrexone; Narcotic Antagonists; Quaternary Ammonium Compounds

Topics: Analgesics, Opioid; Constipation; Drug Approval; Humans; Naltrexone; Narcotic Antagonists; Quaternary Ammonium Compounds; United States; United States Food and Drug Administration

Topics: Analgesics, Opioid; Constipation; Humans; Laxatives; Naltrexone; Narcotic Antagonists; Quaternary Ammonium Compounds

Topics: Analgesics, Opioid; Constipation; Drug Interactions; Humans; Naltrexone; Narcotic Antagonists; Quaternary Ammonium Compounds; Randomized Controlled Trials as Topic; Terminal Care

Topics: Analgesics, Opioid; Constipation; Drug Tolerance; Humans; Laxatives; Naltrexone; Narcotic Antagonists; Quaternary Ammonium Compounds

Topics: Administration, Oral; Analgesics, Opioid; Constipation; Humans; Injections, Subcutaneous; Laxatives; Naltrexone; Narcotic Antagonists; Quaternary Ammonium Compounds

Topics: Analgesics, Opioid; Constipation; Drug Approval; Humans; Injections, Subcutaneous; Naltrexone; Narcotic Antagonists; Palliative Care; Quaternary Ammonium Compounds; Receptors, Opioid, mu; United States; United States Food and Drug Administration

Topics: Analgesics, Opioid; Animals; Anti-Inflammatory Agents; Constipation; Humans; Naltrexone; Narcotic Antagonists; Pain; Piperidines; Pyridines; Quaternary Ammonium Compounds; Receptors, Opioid, mu

Topics: Administration, Oral; Analgesics, Opioid; Clinical Trials, Phase II as Topic; Constipation; Humans; Methadone; Naltrexone; Narcotic Antagonists; Quaternary Ammonium Compounds

Topics: Administration, Oral; Adult; Analgesics, Opioid; Breast Neoplasms; Chemistry, Pharmaceutical; Constipation; Female; Humans; Methadone; Naloxone; Naltrexone; Narcotic Antagonists; Pain; Quaternary Ammonium Compounds

In this preliminary study, we evaluated the effects of methylnaltrexone, a peripheral opioid-receptor antagonist, on chronic opioid-induced gut motility and transit changes in four subjects with chronic methadone-induced constipation. Subjects participated in this single blind, placebo controlled study for up to 8 days. We gave placebo the first day; for the remainder of the study, we gave intravenous methylnaltrexone (0.05-0.45 mg/kg) twice daily. During the study period, we recorded oral-cecal transit time and opioid withdrawal symptoms, as well as laxation response based on the frequency and consistency of the stools. Subjects 1 and 2 who were administered methylnaltrexone 0.45 mg/kg, a dose previously administered in normal volunteers, showed immediate positive laxation. Subject 2, after positive laxation response, had severe abdominal cramping, but showed no opioid systemic signs of withdrawal. The subject was discontinued due to the cramping. In Subjects 3 and 4, we reduced the methylnaltrexone dose to 0.05-0.15 mg/kg. The latter two subjects also had an immediate laxation response during and after intravenous medication without significant side effects. The stool frequency of these four subjects increased from 1-2 times per week before the study to approximately 1.5 stool per day during the treatment period. Oral-cecal transit times of Subjects 1, 3, and 4 were reduced from 150, 150 and 150 min (after placebo) to 90, 60 and 60 min (with methylnaltrexone), respectively. Our preliminary results demonstrate that low dose intravenous methylnaltrexone effectively reversed chronic methadone-induced constipation and delay in gut transit time. Thus, we anticipate that cancer patients receiving chronic opioids may also have increased sensitivity to methylnaltrexone, and that low dose methylnaltrexone may have clinical utility in managing opioid-induced constipation in chronic-pain patients.

Topics: Adult; Analgesics, Opioid; Constipation; Female; Gastrointestinal Motility; Gastrointestinal Transit; Humans; Male; Methadone; Middle Aged; Naltrexone; Narcotic Antagonists; Pilot Projects; Quaternary Ammonium Compounds

Topics: Blood-Brain Barrier; Constipation; Drug Therapy, Combination; Humans; Morphine; Naltrexone; Narcotic Antagonists; Nausea; Neoplasms; Orphan Drug Production; Pain; Quaternary Ammonium Compounds; United States; United States Food and Drug Administration