td-5108 and tegaserod

Irritable bowel syndrome (IBS) is a chronic, recurrent bowel disorder with an unknown etiology, which is most likely multifactorial. Increased mucosal permeability, visceral hypersensitivity and activation status of intestinal mucosal immune cells cause changes in gastrointestinal (GI) motility, secretion and sensation observed in the course of IBS. Permanent, cumbersome symptoms, such as diarrhea, constipation and abdominal pain greatly lower the quality of life of IBS patients. On this basis, according to the Rome IV criteria, different forms of IBS can be distinguished.. This article focuses on the role of serotonin system in the pathophysiology of IBS as a potential therapeutic target. We shortly describe several molecules, associated with serotonin receptors, mainly 5-HT3 receptor antagonists and 5-HT4 receptor agonists, that are used in the treatment of motility disorders and visceral pain in IBS patients. We summarize the findings obtained in the clinical trials and elaborate on the safety of the serotonin ligands. Although the majority of serotonin receptor ligands relieve global symptoms, there are also some adverse effects, which can be dangerous for patients.. We postulate that currently, among all serotonin-targeting compounds, ramosetron is the best treatment option for IBS-D patients, due to its exceptional efficacy in both genders as well as good tolerability. Whereas, tegaserod is highly recommended for IBS-C sufferers. Nevertheless, numerous studies on the new serotonin receptor ligands are conducted to ensure the delivery of novel compounds with improved efficacy and safety profiles.

Topics: Clinical Trials as Topic; Humans; Indoles; Irritable Bowel Syndrome; Lactones; Ligands; Quality of Life; Serotonin 5-HT3 Receptor Antagonists; Serotonin 5-HT4 Receptor Agonists; Sesquiterpenes

The nonselective 5-HT(4) receptor agonists, cisapride and tegaserod have been associated with cardiovascular adverse events (AEs).. To perform a systematic review of the safety profile, particularly cardiovascular, of 5-HT(4) agonists developed for gastrointestinal disorders, and a nonsystematic summary of their pharmacology and clinical efficacy.. Articles reporting data on cisapride, clebopride, prucalopride, mosapride, renzapride, tegaserod, TD-5108 (velusetrag) and ATI-7505 (naronapride) were identified through a systematic search of the Cochrane Library, Medline, Embase and Toxfile. Abstracts from UEGW 2006-2008 and DDW 2008-2010 were searched for these drug names, and pharmaceutical companies approached to provide unpublished data.. Retrieved articles on pharmacokinetics, human pharmacodynamics and clinical data with these 5-HT(4) agonists, are reviewed and summarised nonsystematically. Articles relating to cardiac safety and tolerability of these agents, including any relevant case reports, are reported systematically. Two nonselective 5-HT(4) agonists had reports of cardiovascular AEs: cisapride (QT prolongation) and tegaserod (ischaemia). Interactions with, respectively, the hERG cardiac potassium channel and 5-HT(1) receptor subtypes have been suggested to account for these effects. No cardiovascular safety concerns were reported for the newer, selective 5-HT(4) agonists prucalopride, velusetrag, naronapride, or for nonselective 5-HT(4) agonists with no hERG or 5-HT(1) affinity (renzapride, clebopride, mosapride).. 5-HT(4) agonists for GI disorders differ in chemical structure and selectivity for 5-HT(4) receptors. Selectivity for 5-HT(4) over non-5-HT(4) receptors may influence the agent's safety and overall risk-benefit profile. Based on available evidence, highly selective 5-HT(4) agonists may offer improved safety to treat patients with impaired GI motility.

Topics: Cardiovascular Diseases; Cisapride; Gastrointestinal Agents; Gastrointestinal Diseases; Humans; Indoles; Randomized Controlled Trials as Topic; Serotonin 5-HT4 Receptor Agonists

Ischaemic colitis (IC) is the most common form of ischaemic injury to the gastrointestinal (GI) tract. IC typically presents with the sudden onset of lower abdominal pain, cramping and rectal bleeding, and is usually self-limited with low morbidity, although it may cause gangrenous or fulminant colitis, especially when the right colon is involved. Multiple medical conditions, as well as several pharmacological agents, are associated with IC, including irritable bowel syndrome (IBS) and drugs used for its treatment that act on gut serotonin 5-HT receptors. These include the selective 5-HT(3) receptor antagonist alosetron, currently approved for the treatment of severe diarrhoea-predominant IBS in women who fail to respond to conventional treatment, and cilansetron, another 5-HT(3) receptor antagonist that is no longer in clinical development. In addition, the 5-HT(4) receptor partial agonist tegaserod, which was approved for the treatment of constipation-predominant IBS in women, was associated with IC in the postmarketing setting, as was renzapride, a 5-HT(4) agonist/5-HT(3) antagonist. Although several hypotheses have been proposed, the pathophysiological basis for development of IC with 5-HT(3) receptor antagonists or 5-HT(4) receptor agonists remains unknown. Of interest, several population-based studies demonstrated that a diagnosis of IBS (independent of serotonergic therapies) increases the risk of developing IC 2- to 4-fold. As a result, IBS patients with the acute onset of abdominal pain, tenderness, diarrhoea or lower intestinal bleeding, especially those with predisposing conditions or medications, should be evaluated promptly for IC. The management of IC remains supportive; most cases of non-gangrenous IC, as seen in the alosetron and tegaserod databases, have been transient and have resolved spontaneously without complications or death. Despite the small number of deaths associated with alosetron in patients with complications of constipation and because of the ongoing requirement to prescribe alosetron under a risk management plan, misconceptions persist regarding the definition, incidence, severity and outcome of IC in clinical trials and the postmarketing setting. In this article, the frequency and clinical characteristics of IC associated with the use of alosetron and other serotonergic agents are examined, evidence of an association between IC and IBS is reviewed, and a scoring system to aid in the diagnosis of IC in any clinical situatio

Topics: Animals; Carbolines; Colitis, Ischemic; Female; Humans; Indoles; Irritable Bowel Syndrome; Male; Serotonin 5-HT3 Receptor Antagonists; Serotonin 5-HT4 Receptor Agonists

The present review has several objectives, the first of which is to review the pharmacology and selectivity of serotonergic agents to contrast the older serotonergic agents (which were withdrawn because of cardiac or vascular adverse effects) with the newer generation serotonin receptor subtype 4 agonists. Second, the chloride ion secretagogues that act through the guanylate cyclase C receptor are appraised and their pharmacology is compared with the approved medication, lubiprostone. Third, the efficacy and safety of the application of bile acid modulation to treat constipation are addressed. The long-term studies of surgically induced excess bile acid delivery to the colon are reviewed to ascertain the safety of this therapeutic approach. Finally, the new drugs for opiate-induced constipation are introduced. Assuming these drugs are approved, practitioners will have a choice; however, patient responsiveness will be based on trial and error. Nevertheless, the spectrum of mechanisms and demonstrated efficacy and safety augur well for satisfactory treatment outcomes.

Topics: Alprostadil; Bile Acids and Salts; Chloride Channels; Chronic Disease; Constipation; Gastrointestinal Agents; Humans; Indoles; Lubiprostone; Organic Anion Transporters, Sodium-Dependent; Peptides; Receptors, Serotonin, 5-HT4; Serotonin 5-HT4 Receptor Agonists; Serotonin Agents; Symporters

Chronic idiopathic constipation (CIC) and irritable bowel syndrome with constipation (C-IBS) are commonly reported gastrointestinal (GI) disorders that have a major impact on health and quality of life. Patients experience a range of symptoms of which infrequency of bowel movement is but one and report that straining, the production of hard stools, and unproductive urges are more bothersome than stool infrequency. Additionally, in C-IBS, patients report abdominal pain and bloating as particularly troubling. Traditional treatments, such as laxatives, are often ineffective, especially in more severe constipation over the long term. In a population-based survey of constipation sufferers, half were not satisfied with their current treatment, due predominantly to poor efficacy. 5-Hydroxytryptamine receptor 4 (5-HT4) agonists stimulate GI motility and intestinal secretion, and tegaserod has demonstrated efficacy in improving bowel habit. Tegaserod also improves constipation-associated symptoms including bloating, abdominal discomfort, stool consistency, and straining in patients with both CIC and C-IBS. However, tegaserod has been withdrawn due to an association with serious adverse cardiovascular effects. Further 5-HT(4) receptor agonists, including prucalopride and TD-5108 are in development and show exciting results in clinical studies in CIC patients, suggesting further product approvals are likely. Headache and diarrhea are the most commonly reported adverse event with this class of agent. Recently a novel prosecretory agent has been approved for the treatment of both CIC and C-IBS. Lubiprostone stimulates chloride secretion through activation of type-2 chloride channels, increasing intestinal secretion and transit, and its use has been associated with improvements in bowel habit and symptoms of constipation. Nausea, diarrhea, and headache are the most commonly reported adverse events. Linaclotide also stimulates intestinal chloride secretion, but this molecule achieves this indirectly, through the activation of guanylate cyclase C. Data are emerging, but the efficacy and safety profile of this agent in the treatment of CIC and C-IBS appears encouraging.

Topics: Alprostadil; Azabicyclo Compounds; Benzofurans; Chloride Channels; Chronic Disease; Constipation; Gastrointestinal Agents; Gastrointestinal Motility; Guanylate Cyclase; Humans; Indoles; Irritable Bowel Syndrome; Laxatives; Lubiprostone; Peptides; Safety; Serotonin 5-HT4 Receptor Agonists; Serotonin Receptor Agonists; Treatment Outcome

Tegaserod, a selective and partial agonist at the 5-hydroxytryptamine (5-HT [serotonin]) receptor subtype 4 (5-HT4), is the only United States Food and Drug Administration-approved drug for the treatment of constipation-predominant irritable bowel syndrome (IBS) in women. The drug's stimulation of 5-HT4 receptors on intestinal enterocytes increases peristaltic activity and fluid secretion into the gut lumen, facilitating stool passage. In addition, affinity of tegaserod for 5-HT4 receptors modulates visceral sensitivity, which helps alleviate abdominal pain associated with constipation-predominant IBS. The drug's pharmacokinetic and pharmacodynamic parameters do not differ significantly with age or sex. Tegaserod safely and effectively relieves overall gastrointestinal symptoms and abdominal discomfort and normalizes bowel habits in patients with constipation-predominant IBS. It is associated with few drug interactions. In clinical studies, tegaserod was well tolerated, and its adverse-effect profile was similar to that of placebo. Severe diarrhea, as well as abdominal pain, flatulence, headache, and nausea, were the most commonly reported events. Patients who experience severe diarrhea should discontinue the drug. With the data available, tegaserod remains an option for patients with constipation-predominant IBS.

Topics: Constipation; Female; Gastrointestinal Agents; Humans; Indoles; Irritable Bowel Syndrome; Serotonin 5-HT4 Receptor Agonists; Serotonin Receptor Agonists; Treatment Outcome

Gastroesophageal reflux disease (GERD) is increasingly common worldwide; symptoms differ between individuals and endoscopically visible injury is present in only about 50% of cases. Although GERD is a disorder of gastrointestinal motility and structure, the most effective therapy is based on the use of acid antisecretory drugs. Proton pump inhibitors (PPIs), the most effective class of acid suppression agents to date, have revolutionised the management of GERD. However, PPIs do have some shortcomings and recent developments include documentation of increased healing rates with more prolonged acid suppression, more prolonged acid suppression with a new PPI (tenatoprazole) and more rapid onset of acid suppression with a new class of drugs, the reversible, potassium-competitive acid blockers. Studies with motility agents, such as the 5-HT(4) partial agonist tegaserod and the GABA(B) agonist baclofen, indicate that motility is important in the pathogenesis of GERD but, for several reasons, it will be a challenge to develop new classes of drug that outperform current PPIs with respect to efficacy, broad applicability and safety.

Topics: Animals; GABA-A Receptor Agonists; Gastroesophageal Reflux; Histamine H2 Antagonists; Humans; Indoles; Proton Pump Inhibitors; Serotonin 5-HT4 Receptor Agonists

This article reviews the safety and tolerability profile of tegaserod, a novel selective partial agonist of the serotonin 5-HT(4) receptor. Tegaserod was recently approved for the treatment of women with irritable bowel syndrome (IBS) with constipation. Tegaserod exhibits rapid absorption from the small intestine, and is excreted unchanged in the faeces and as metabolites in the urine. Meal ingestion decreases its bioavailability. There is little effect of age or gender on pharmacokinetics, although plasma levels may be slightly higher in the elderly. Tegaserod has no effect on plasma levels of other drugs metabolised by cytochrome P450 enzyme systems. Gastrointestinal symptoms are the most common adverse effects of tegaserod therapy. In data pooled from phase III randomised controlled trials (RCTs) in IBS with constipation patients, diarrhoea was reported by 8.8% of patients treated with tegaserod 6mg twice daily versus 3.8% of patients receiving placebo. Similar rates have been observed in international post-US marketing RCTs. In most patients, tegaserod-induced diarrhoea was mild and transient. In RCTs, it did not elicit fluid or electrolyte disturbances, and fewer than 3% of IBS patients discontinued tegaserod due to diarrhoea. Since its release, rare cases of more severe diarrhoea and ischaemic colitis have been reported. The incidence of other gastrointestinal symptoms (e.g. abdominal pain, nausea, and flatulence) has been similar among tegaserod-treated patients and placebo-treated patients. Pooled analysis of phase III RCTs and post-US marketing RCTs have not demonstrated significant differences between tegaserod-treated patients and placebo-treated patients in the incidence of abdominal-pelvic surgery. There is no convincing evidence that rebound gastrointestinal symptoms occur upon termination of tegaserod therapy. Pooled analysis of phase III RCTs demonstrated an increase in the incidence of headaches among tegaserod-treated patients (6mg twice daily) compared with placebo-treated patients (15% vs 12.3%, respectively, p < 0.05), although post-US marketing RCTs have not observed this increase. Other extra-gastrointestinal adverse events occur with similar frequency among tegaserod-treated patients and placebo-treated patients. Tegaserod-treated patients in RCTs have not demonstrated significant prolongation of the QTc interval or cardiac arrhythmias compared with placebo-treated patients. Supra-therapeutic doses in healthy volunteers did not eff

Topics: Drug Interactions; Humans; Indoles; Irritable Bowel Syndrome; Product Surveillance, Postmarketing; Randomized Controlled Trials as Topic; Serotonin 5-HT4 Receptor Agonists

Activation of serotonin 5-HT(4) receptors has been proposed as treatment for irritable bowel syndrome, a common, complex and distressing gastrointestinal disorder. Abnormal intestinal motility and sensitivity in irritable bowel syndrome patients can result in diarrhea, constipation, abdominal pain, bloating, headache and fatigue; these and other symptoms can lead to exacerbation of psychological stress, which may in turn induce further physiological abnormalities and patient discomfort. The serotonin agonist tegaserod binds with high affinity to 5-HT(4) receptors and has demonstrated potent pharmacological effects on the mid- and distal gut. Tegaserod has been safely employed in clinical trials where it has demonstrated efficacy in normalizing intestinal function, thereby improving irritable bowel syndrome symptoms.

Topics: Constipation; Humans; Indoles; Irritable Bowel Syndrome; Randomized Controlled Trials as Topic; Receptors, Serotonin, 5-HT4; Serotonin 5-HT4 Receptor Agonists

Functional gastrointestinal disorders are characterised by central and peripheral physiological changes, associated with psychological factors. Successful drug development has been hindered by lack of adequate characterisation of the nature of symptoms and their physiological and psychological correlates. Animal models of chronic stress are lacking. High levels of drug safety are now demanded for treating non-life threatening conditions. Once close to market, patient pressure groups, health care providers and insurers, government, and the internet can all influence a drug's success. Serotonin-modifying drugs have been the main recent focus of development, with mixed results. Cisapride has been withdrawn because of concerns related to QT prolongation and cardiac arrhythmias. The 5-HT3 antagonists have been developed on the questionable assumption that they modify visceral sensation in patients. Problems have arisen with alosetron being associated with ischaemic colitis and a high incidence of constipation. The 5-HT4 agonists have their major effect on inducing peristalsis, and may modify gut secretion and sensory function. Tegaserod and prucalopride show promise in patients with constipation and related symptoms. 5-HT1 agonists may play a role in treating functional dyspepsia, partly by improving impaired gastric accommodation to a meal. Antidepressants, often found to be clinically beneficial in these disorders, also affect serotonin metabolism. Past successes, such as loperamide or the somatostatin analogue octreotide, involved targeting end organ receptors influencing motor function or secretion. Modifying sensory function is much more challenging. Future research with novel compounds need to keep these recent lessons in mind.

Topics: Antidepressive Agents; Benzofurans; Carbolines; Cisapride; Constipation; Drug Industry; Gastrointestinal Agents; Humans; Indoles; Irritable Bowel Syndrome; Serotonin 5-HT3 Receptor Antagonists; Serotonin 5-HT4 Receptor Agonists; Serotonin Antagonists; Serotonin Receptor Agonists

Tegaserod, an orally active, potent 5-hydroxytryptamine-4 serotonin receptor agonist, was previously indicated for irritable bowel syndrome but was voluntarily withdrawn due to potential cardiovascular side effects. In vitro studies suggested that tegaserod increased platelet aggregation, but these results were not reproduced or were inconclusive. We sought to assess ex vivo effects of tegaserod on platelet aggregation.. In this double-blind, placebo-controlled, crossover study, we randomized a majority of healthy patients with no history of cardiovascular risk factors (n = 21) to receive tegaserod or matching placebo for 7 + 2 days followed by a 7- to 10-day washout period, and then patients were crossed over to the other study drug for the next 7 + 2 days. Unstimulated and agonist-stimulated platelet aggregation; P-selectin expression; serum thromboxane (Tx)B. There was no significant difference in percentage change in unstimulated or adenosine diphosphate (ADP)- and ADP + serotonin-, collagen- and thrombin receptor activating peptide-induced maximum platelet aggregation and in platelet P-selectin expression in the presence of tegaserod at any time point when compared to placebo. Similarly, there was no significant difference in percentage change in serum TxB. This comprehensive pharmacodynamic study, by employing established markers used in prior investigations, which have been considered by the Food and Drug Administration to indicate drug-related platelet effects, does not demonstrate any influence of tegaserod treatment on platelet function.

Topics: Administration, Oral; Adult; Blood Platelets; Cross-Over Studies; Double-Blind Method; Female; Healthy Volunteers; Humans; Indoles; Male; Platelet Activation; Platelet Aggregation; Platelet Function Tests; Serotonin 5-HT4 Receptor Agonists; Treatment Outcome; Young Adult

Topics: Administration, Oral; Adult; Anti-Bacterial Agents; Arrhythmias, Cardiac; Asian People; Benzamides; Case-Control Studies; Cisapride; Cross-Over Studies; Double-Blind Method; Electrocardiography; Female; Humans; Indoles; Irritable Bowel Syndrome; Long QT Syndrome; Male; Morpholines; Moxifloxacin; Piperidines; Placebos; Serotonin 5-HT4 Receptor Agonists; Serotonin Receptor Agonists

To evaluate the potential role of tegaserod in the management of functional dyspepsia (FD) and gastroesophageal reflux disease (GERD) in patients with chronic constipation and to determine the possible efficacy of tegaserod on solid-phase gastric emptying and gastric hypersensitivity.. This was an exploratory open-label trial of tegaserod therapy for dyspepsia and reflux symptoms in patients with chronic constipation. The study cohort consisted of 90 patients randomized to three treatment groups for a study period of 4 weeks (tegaserod 6 mg, twice daily; esomeprazole 40 mg, once daily; tegaserod 6 mg, twice daily plus esomeprazole 40 mg, once daily). Twenty healthy volunteers provided control values. Clinical symptoms were evaluated by one of the investigators using a Gastrointestinal Symptom Rating Scale (GSRS). Solid-phase gastric emptying and colonic transit were measured by the radiopaque barium marker method, and the water load test (WLT) was used to evaluate gastric sensation and the function of proximal stomach. The proportions of patients with complete relief of epigastric pain /discomfort, epigastric fullness, early satiety and heartburn in the tegaserod group and the tegaserod plus esomeprazole group were compared with the esomeprazole group, respectively.. The mean global gastrointestinal (GI) scores of all three treatment groups reported using the GSRS showed the same trend, with decreasing scores over the 4-week study period indicating a reported decreasing severity of symptoms that was significantly different from baseline values. Patients in the tegaserod plus esomeprazole group reported the lowest global GI scores after 4 weeks, as expected. Solid-phase gastric emptying (GER) and colonic transit (CTT) increased significantly in the tegaserod 6 mg twice daily group compared with baseline. These parameters did not change in the esomeprazole group at week 4 compared with baseline. In terms of gastric sensation, in the tegaserod group, the proportions of patients with hypersensitivity of the first perception threshold did not change at week 2 or week 4 compared with baseline; however, in this group and in the tegaserod plus esomeprazole group, the proportions of patients with hypersensitivity of discomfort threshold decreased significantly at week 4 compared with baseline. In the esomeprazole group, there were no changes in the proportions of patients with hypersensitivity of the first perception threshold and discomfort threshold at week 2 or 4 compared with baseline. No severe adverse events were recorded, and the medications were in general well-tolerated.. Tegaserod is effective and safe at improving dyspepsia and reflux symptoms in patients with chronic constipation, and tegaserod plus esomeprazole is superior to esomeprazole alone in the resolution of epigastric pain/discomfort and heartburn.

Topics: Adolescent; Adult; Aged; Aged, 80 and over; Analysis of Variance; Anti-Ulcer Agents; Chronic Disease; Cohort Studies; Constipation; Drug Therapy, Combination; Dyspepsia; Esomeprazole; Female; Gastric Emptying; Gastroesophageal Reflux; Gastrointestinal Transit; Heartburn; Humans; Indoles; Male; Middle Aged; Serotonin 5-HT4 Receptor Agonists; Treatment Outcome

Opioid neurons exhibit tonic restraint on intestinal motility; opioid antagonists stimulate peristalsis and increase transit. In vitro, 5-hydroxytryptamine (5-HT4) agonists combined with selective opioid antagonists significantly increased colonic propulsion relative to a 5-HT4 agonist alone. We hypothesized that the combination of 5-HT4 agonist and non-selective opioid antagonist enhances intestinal transit more than either treatment alone in female constipation-predominant irritable bowel syndrome (C-IBS) patients. Our aim was to examine the effect of tegaserod 6 mg b.i.d. alone and combined with naltrexone 50 mg on intestinal transit and stool characteristics in females with C-IBS. Forty-eight patients were randomized to tegaserod alone, naltrexone alone or in combination with tegaserod or placebo for 6 days. Small bowel, ascending colon half-life (in pharmacokinetics) (t1/2), and colonic geometric centre (8, 24, 48 h) were assessed by scintigraphy. Tegaserod increased small bowel (P < 0.01) and colon transit (P < 0.01). Naltrexone did not accelerate colonic transit relative to placebo. Combination treatment did not significantly accelerate transit relative to tegaserod alone. Tegaserod and tegaserod with naltrexone resulted in looser stool form (P < 0.01). In female C-IBS patients, tegaserod accelerates small bowel and colon transit and contributed to looser stool consistency. Use of naltrexone, 50 mg, does not support the hypothesis that combination of 5-HT4 agonist and non-selective opioid antagonist enhances intestinal transit.

Topics: Adult; Constipation; Double-Blind Method; Drug Therapy, Combination; Female; Gastrointestinal Motility; Humans; Indoles; Irritable Bowel Syndrome; Male; Middle Aged; Naltrexone; Narcotic Antagonists; Radionuclide Imaging; Serotonin 5-HT4 Receptor Agonists; Serotonin Receptor Agonists

Polyethylene glycol (PEG) 3350 (MiraLax) and tegaserod (Zelnorm), a serotonin subtype 4 receptor partial agonist, are currently approved for treatment of constipation. This study was designed to compare the efficacy of each product over a 4-wk treatment period.. Study patients who met defined criteria for chronic constipation were randomized in this open-labeled, parallel, multicenter study to receive the PEG laxative as a single daily dose of 17 g or tegaserod tablets 6 mg b.i.d., for 28 days. As a primary end point, treatment success was defined for each patient as relief of modified ROME criteria for constipation for 50% or more of their treatment weeks. Various secondary measures were also assessed. An interactive voice response system (IVRS) recorded patient reported daily bowel movement experience and study efficacy and safety information.. A total of 237 patients were enrolled and received treatment at one of 25 centers. Successful treatment according to the primary end point was seen in 50.0% of the PEG and 30.8% of tegaserod patients (P= 0.003). By treatment weeks 3 and 4, significantly more PEG patients were successfully treated according to primary and secondary response definitions. PEG patients experienced more bowel movements per week (P= 0.019) and had significantly greater improvement in constipation symptoms (P= 0.016) based on results from a validated patient self-reported questionnaire. Tegaserod patients experienced a significantly higher incidence of headaches. Otherwise, there were no significant differences in adverse events.. While PEG laxative and tegaserod are safe for their intended use in chronic constipation, PEG had superior efficacy, caused fewer headaches, and produced greater improvement of constipation symptoms.

Topics: Adult; Aged; Aged, 80 and over; Cathartics; Chronic Disease; Constipation; Female; Gastrointestinal Agents; Humans; Indoles; Male; Middle Aged; Polyethylene Glycols; Serotonin 5-HT4 Receptor Agonists; Treatment Outcome

We performed a double-blind randomized placebo-controlled pilot study to determine the efficacy of tegaserod (Zelnorm) in treating constipation in 15 patients with Parkinson's disease (PD). There was a trend for improvement in the Subject's Global Assessment (SGA) of satisfaction with bowel habits (NS) and the total SGA (including abdominal discomfort, bothersome constipation, and satisfaction; NS).

Topics: Aged; Constipation; Double-Blind Method; Female; Gastrointestinal Agents; Gastrointestinal Motility; Humans; Indoles; Male; Middle Aged; Parkinson Disease; Patient Satisfaction; Serotonin 5-HT4 Receptor Agonists; Serotonin Receptor Agonists

Serotonin (5-hydroxytryptamine [5-HT]) synthesized and released in enterochromaffin (EC) cells participates in various functions in the gastrointestinal tract by acting on a diverse range of 5-HT receptors (HTRs) expressed on smooth muscle, enteric neurons, and epithelial cells. We previously observed that genes encoding HTR2A, HTR2B, and HTR4 are expressed in murine intestinal organoids, suggesting the expression of these HTRs in intestinal epithelial cells. The present study investigated the localization of these HTRs in the murine intestine by immunofluorescence staining. HTR2A, HTR2B, and HTR4 localized in individual solitary cells in the epithelium, while HTR2C was observed in the lamina propria. In the epithelium, HTR2A, HTR2B, and HTR4 colocalized with 5-HT, and HTR4 colocalized with glucagon-like peptide 1 (GLP-1) and peptide YY (PYY). Murine intestinal organoids show a colocalization pattern that is similar to in vivo HTR2A and HTR4 with 5-HT, GLP-1, and PYY. Intraperitoneal and intragastric administration of tegaserod, an HTR4 agonist, failed to alter plasma GLP-1 levels in fasted mice. However, intragastric but not intraperitoneal administration of tegaserod reduced dietary lipid-induced increases of plasma GLP-1 levels. This action of tegaserod was inhibited by co-administration of RS39604, an HTR4 antagonist. These results suggest that murine ileal GLP-1/PYY-producing enteroendocrine (EE) cells express HTR4, while 5-HT-producing EC cells express HTR2A, HTR2B, and HTR4. In addition, the observations regarding in vivo GLP-1 secretion suggest that HTR4 signaling in ileal EE cells suppresses dietary lipid-induced GLP-1 secretion. We thus propose that EC and EE cells may interact with each other through paracrine signaling mechanisms.

Topics: Animals; Cells, Cultured; Enteroendocrine Cells; Gastrointestinal Agents; Glucagon-Like Peptide 1; Indoles; Male; Mice; Mice, Inbred C57BL; Receptors, Serotonin, 5-HT4; Serotonin 5-HT4 Receptor Agonists; Serotonin 5-HT4 Receptor Antagonists

The Janus kinase (JAK)/signal transducer and activator of transcription 3 (STAT3) signaling pathway plays central roles in cancer cell growth and survival. Drug repurposing strategies have provided a valuable approach for developing antitumor drugs. Zelnorm (tegaserod maleate) was originally designed as an agonist of 5-hydroxytryptamine 4 receptor (5-HT4R) and approved by the FDA for treating irritable bowel syndrome with constipation (IBS-C). Through the use of a high-throughput drug screening system, Zelnorm was identified as a JAK/STAT3 signaling inhibitor. Moreover, the inhibition of STAT3 phosphorylation by Zelnorm was independent of its original target 5-HT4R. Zelnorm could cause G1 cell cycle arrest, induce cell apoptosis and inhibit the growth of a variety of cancer cells. The present study identifies Zelnorm as a novel JAK/STAT3 signaling inhibitor and reveals a new clinical application of Zelnorm upon market reintroduction.

Topics: Animals; Antineoplastic Agents; Apoptosis; Cell Line, Tumor; Cell Proliferation; G1 Phase Cell Cycle Checkpoints; Humans; Indoles; Janus Kinases; Mice, Nude; Neoplasms; Protein Kinase Inhibitors; Receptors, Serotonin, 5-HT4; Serotonin 5-HT4 Receptor Agonists; Signal Transduction; STAT3 Transcription Factor

Tegaserod is a 5-hydroxytryptamine type 4 (5-HT. Rats were treated with a single dose of tegaserod (5 mg/kg) and tissue samples of the oesophagus and distal colon were prepared and level of GRK2 and GRK6 protein expression was determined using western blotting. The immunodensity of GRK2 and GRK6 was normalized against the loading control β-actin and compared with control animals. Acute administration of tegaserod for 1, 2, 3, 4, 6, and 8 h did not change significantly the immunodensity of GRK2 or GRK6 in the oesophagus or GRK2 in the distal colon when compared with control animals. This may indicate that the basal level of GRK2 and GRK6 expression is sufficient to regulate the desensitization of 5-HT

Topics: Animals; G-Protein-Coupled Receptor Kinase 2; G-Protein-Coupled Receptor Kinases; Gastrointestinal Tract; Indoles; Male; Rats, Sprague-Dawley; Receptors, Serotonin, 5-HT4; Serotonin 5-HT4 Receptor Agonists; Time Factors

Glycans attached to the cell surface via proteins or lipids or exposed in the extracellular matrix affect many cellular processes, including neuritogenesis, cell survival and migration, as well as synaptic activity and plasticity. These functions make glycans attractive molecules for stimulating repair of the injured nervous system. Yet, glycans are often difficult to synthesize or isolate and have the disadvantage to be unstable in a complex tissue environment. To circumvent these issues, we have screened a library of small organic compounds to search for structural and functional mimetics of the neurostimulatory glycan polysialic acid (PSA) and identified the 5-HT4 receptor agonist tegaserod as a PSA mimetic. The PSA mimicking activity of tegaserod was shown in cultures of central and peripheral nervous system cells of the mouse and found to be independent of its described function as a serotonin (5-HT4) receptor agonist. In an in vivo model for peripheral nerve regeneration, mice receiving tegaserod at the site of injury showed enhanced recovery compared to control mice receiving vehicle control as evidenced by functional measurements and histology. These data indicate that tegaserod could be repurposed for treatment of nervous system injuries and underscores the potential of using small molecules as mimetics of neurostimulatory glycans.

Topics: Animals; Biomimetics; Cells, Cultured; Cerebellum; Femoral Nerve; Ganglia, Spinal; Indoles; Mice; Mice, Inbred C57BL; Mice, Knockout; Models, Molecular; Motor Neurons; Nerve Regeneration; Neural Cell Adhesion Molecules; Neurons; Neuroprotective Agents; Peripheral Nerve Injuries; Recovery of Function; Schwann Cells; Serotonin 5-HT4 Receptor Agonists; Sialic Acids

The 5-HT(4) receptor agonist tegaserod (TEG) has been reported to modulate visceral pain. However, the underlying mechanism remains unknown. The objective of the present study was to examine the analgesic mechanism and site of action of TEG. In male rats, visceral pain was assessed by measuring visceromotor response (VMR) to colorectal distension (CRD). Inflammation was induced by intracolonic injection of tri-nitrobenzene sulfonic acid (TNBS). The effect of TEG on the VMR was tested by injecting intraperitoneal (i.p.), intrathecal (i.t.), intracerebroventricular (i.c.v) or in the rostroventral medulla (RVM). The effect of the drug was also tested on responses of CRD-sensitive pelvic nerve afferents (PNA) and lumbo-sacral (LS) spinal neurons. Systemic injection of TEG attenuated VMR in naive and TNBS-treated rats. Similarly, supraspinal, but not spinal, injection of TEG attenuated the VMR. While GR113808, (selective 5-HT(4) antagonist) blocked the effect, naloxone (NLX) an opioid receptor antagonist reversed the effect of TEG. Although i.t. NLX did not block the inhibitory effect of TEG in VMR study, i.t. injection of α2-adrenergic receptor antagonist yohimbine blocked the effect of TEG when given systemically. While TEG had no effect on the responses of CRD-sensitive PNA, it inhibited the responses of CRD-sensitive LS neurons in spinal intact condition. This inhibition was blocked by GR113808, NLX and β-funaltrexamine (β-FNA) when injected into the RVM. Results indicate that TEG produces analgesia via activation of supraspinal 5-HT(4) receptors which triggers the release of opioids at supraspinal site, which activates descending noradrenergic pathways to the spinal cord to produce analgesia.

Topics: Abdominal Muscles; Analgesics; Animals; Colon; Indoles; Male; Medulla Oblongata; Muscarinic Antagonists; Narcotic Antagonists; Neurons; Neurons, Afferent; Periaqueductal Gray; Rats; Rats, Sprague-Dawley; Receptors, Serotonin, 5-HT4; Serotonin 5-HT4 Receptor Agonists; Serotonin Antagonists; Spinal Cord; Trinitrobenzenesulfonic Acid; Visceral Pain

Postoperative ileus (POI) is an impairment of coordinated gastrointestinal (GI) motility that develops as a consequence of abdominal surgery and is a major factor contributing to patient morbidity and prolonged hospitalization. The aim of this study was to investigate the effects of different 5-hydroxytryptamine 4 (5-HT₄) receptor agonists, which stimulate excitatory pathways, on a POI model.. The experimental model of POI in guinea pigs was created by laparotomy, gentle manipulation of the cecum for 60 seconds, and closure by suture, all under anesthesia. Different degrees of restoration of GI transit were measured by the migration of charcoal. Colonic transit was indirectly assessed via measurement of fecal pellet output every hour for 5 hours after administration of various doses of mosapride, tegaserod, prucalopride, and 5-HT.. Charcoal transit assay showed that various 5-HT₄ receptor agonists can accelerate delayed upper GI transit in a dose-dependent manner. However, fecal pellet output assay suggested that only prucalopride had a significant effect in accelerating colonic motility in POI.. Although mosapride, tegaserod, and prucalopride produce beneficial effects to hasten upper GI transit in the POI model, prucalopride administered orally restores lower GI transit as well as upper GI transit after operation in a conscious guinea pig. This drug may serve as a useful candidate for examination in a clinical trial for POI.

Topics: Administration, Oral; Animals; Benzamides; Benzofurans; Charcoal; Colon; Dose-Response Relationship, Drug; Gastrointestinal Motility; Guinea Pigs; Ileus; Indoles; Laparotomy; Male; Morpholines; Postoperative Complications; Serotonin; Serotonin 5-HT4 Receptor Agonists

The 5-HT(4) receptor agonists, and gastrointestinal (GI) prokinetic agents, cisapride and tegaserod, lack selectivity for the 5-HT(4) receptor. Cisapride is a potent human ether-à-go-go-related gene (hERG) potassium channel inhibitor while cisapride and tegaserod have significant affinity for 5-HT(1) and 5-HT(2) receptor subtypes. Marketing of both compounds was discontinued due to cardiovascular concerns (cardiac arrhythmias with cisapride and ischemic events with tegaserod). The reported association of tegaserod with ischemia has been postulated to involve coronary artery constriction or augmentation of platelet aggregation. This in vitro study investigated the effects of two of the new generation of highly selective 5-HT(4) receptor agonists, velusetrag and TD-8954, on canine, porcine and human coronary artery tone, human platelet aggregation and hERG potassium channel conductance. No significant off-target actions of velusetrag or TD-8954 were identified in these, and prior, studies. While cisapride inhibited potently the hERG channel currents, tegaserod failed to affect platelet aggregation, and had only a small contractile effect on the canine coronary artery at high concentrations. Tegaserod inhibited the 5-HT-induced contractile response in the porcine coronary artery. New generation 5-HT(4) receptor agonists hold promise for the treatment of patients suffering from GI motility disorders with a reduced cardiovascular risk.

Topics: Adult; Animals; Azabicyclo Compounds; Benzimidazoles; CHO Cells; Cisapride; Coronary Vessels; Cricetinae; Cricetulus; Dogs; Ether-A-Go-Go Potassium Channels; Female; Humans; In Vitro Techniques; Indoles; Male; Middle Aged; Piperidines; Platelet Aggregation; Serotonin 5-HT4 Receptor Agonists; Swine

Besides acting as gastrointestinal prokinetic agents, 5-hydroxytryptamine(4) (5-HT(4)) receptor agonists can induce positive inotropism in human isolated atrium, but not in ventricles. We pharmacologically evaluated the gastroprokinetic 5-HT(4) receptor agonists tegaserod, prucalopride, R199715, cisapride, the cisapride metabolite norcisapride, and the 5-HT(3) receptor agonist MKC773 on human isolated myocardial trabeculae, and compared their effects with those induced by 5-HT and 5-methoxytryptamine (5-MeOT).. Atrial and ventricular trabeculae were paced and changes in contractile force were studied in the absence or presence of the 5-HT(4) receptor antagonist GR113808. Partial agonism was assessed using 5-HT(4) receptor agonists as antagonists against 5-HT. To test the contribution of L-type calcium channels, the inotropic responses to 5-HT and 5-MeOT were studied in the absence or presence of verapamil.. Like 5-HT and 5-MeOT, cisapride and tegaserod, but not prucalopride, R19971 and MKC-733, induced concentration-dependent positive inotropic responses on atrial trabeculae, which were abolished by GR113808. The L-type calcium channel blocker verapamil attenuated inotropic responses to 5-HT and 5-MeOT. None of the agonists affected the contraction of left ventricular trabeculae. Concentration response curves to 5-HT were shifted to the right in the presence of prucalopride, cisapride, tegaserod and R199715, but not MKC-773.. We conclude that (i) inotropic responses to 5-HT and 5-MeOT seem to depend on L-type calcium channels, (ii) tegaserod and cisapride behave as partial 5-HT(4) receptor agonists, while prucalopride, norcisapride and MKC-733 cause no significant effects on human atrial trabeculae, (iii) R199715 seems to behave as a 5-HT(4) receptor antagonist.

Topics: 5-Methoxytryptamine; Adolescent; Adult; Aged; Benzofurans; Calcium Channels; Child; Cisapride; Female; Gastrointestinal Agents; Heart Atria; Heart Ventricles; Humans; Indoles; Male; Middle Aged; Muscle Contraction; Myocardium; Pyridines; Quinuclidines; Receptors, Serotonin, 5-HT4; Serotonin; Serotonin 5-HT4 Receptor Agonists; Serotonin Antagonists; Sulfonamides; Young Adult

This study examined whether the drug-receptor-binding sites of 5 selected human 5-HT(4) receptor splice variants [h5-HT4(a), h5-HT4(b), h5-HT4(c), h5-HT4(d) and h5-HT4(g)] display preferential affinities towards agonists. The agonists selected on the basis of chemical diversity and clinical relevance were: 5-HT4 benzamides, renzapride, zacopride and prucalopride; the benzimidazolones, DAU 6236 and BIMU 1; the aromatic ketone, RS67333, and the indole carbazimidamide tegaserod. The rank order of affinities ranging across the splice variants was: tegaserod (pKi: 7.38-7.91) > or = Y-36912 (pKi: 7.03-7.85) = BIMU 1 (pKi: 6.92-7.78) > or = DAU 6236 (pKi: 6.79-7.99) > or = 5-HT (pKi: 5.82-7.29) > or = 5-MeOT (pKi: 5.64-6.83) > or = renzapride (pKi: 4.85-5.56). We obtained affinity values for the 5-HT4(b), (d) and (g) variants for RS67333 (pKi: 7:48-8.29), prucalopride (pKi: 6.86-7.37) and zacopride (pKi: 5.88-7.0). These results indicate that the ligands interact with the same conserved site in each splice variant. Some splice variants have a higher affinity for certain agonists and the direction of selectivity followed a common trend of lowest affinity at the (d) variant. However, this trend was not evident in functional experiments. Our findings suggest that it may be possible to design splice variant selective ligands, which may be of relevance for experimental drugs but may be difficult to develop clinically.

Topics: Aniline Compounds; Animals; Benzamides; Benzimidazoles; Benzofurans; Binding Sites; Binding, Competitive; Bridged Bicyclo Compounds, Heterocyclic; Chlorocebus aethiops; COS Cells; Cyclic AMP; Dose-Response Relationship, Drug; Humans; Indoles; Kinetics; Ligands; Piperidines; Protein Isoforms; Receptors, Serotonin, 5-HT4; Serotonin 5-HT4 Receptor Agonists; Serotonin Antagonists

Acute colonic pseudo-obstruction is characterized by symptoms, signs and radiologic appearance of large bowel obstruction in the absence of a true mechanical obstruction. Several pharmacologic treatments have been proposed. We present a case of a patient with Guillain-Barré syndrome complicated by acute colonic pseudo-obstruction, who had a clinical response to tegaserod, a partial 5-hydroxytryptamine type-4 agonist. 5-Hydroxytryptamine type 4 agonists may be an option in the treatment of acute colonic pseudo-obstruction.

Topics: Acute Disease; Colonic Pseudo-Obstruction; Drug Partial Agonism; Guillain-Barre Syndrome; Humans; Indoles; Male; Middle Aged; Serotonin 5-HT4 Receptor Agonists

Increased cholinergic stimulation and accelerated gastrointestinal (GI) transit may be produced by direct stimulation of the acetylcholine (ACh) receptor with an appropriate agonist by increased release of ACh from cholinergic nerve terminals or by a decreased removal or breakdown of ACh within cholinergic synapses. The acetylcholinesterase inhibitor, neostigmine, and the 5-HT(4) receptor partial agonist tegaserod, are two agents with known prokinetic activity which work by different mechanisms that result in increased levels of ACh at cholinergic synapses innervating intestinal smooth muscle. Here, we aimed to investigate the potential synergistic effect on colonic transit that may occur with concomitant use of these two agents. Colonic transit was indirectly assessed in rats via measurements of fecal pellet output every 30 min for 2.5 h following administration of neostigmine (0.003-0.1 mg kg(-1), i.p.), tegaserod (0.01-1.0 mg kg(-1), i.p.), or a combination of both compounds. When administered alone, neostigmine or tegaserod caused a dose-dependent increase in fecal pellet output. In combination, low doses of the two agents which did not produce statistically significant effects alone, compared to the vehicle, caused a significant increase in fecal pellet output. Combinations of higher doses of neostigmine and tegaserod did not display synergy. In summary, when combined at low doses, neostigmine and tegaserod produce synergistic effects manifested by a statistically significant increase in the expulsion of fecal pellets. A combination of an anticholinesterase agent with a 5-HT(4) receptor agonist may prove to be a useful therapeutic approach to treat conditions associated with slow GI transit.

Topics: Animals; Cholinesterase Inhibitors; Colon; Defecation; Gastrointestinal Transit; Indoles; Male; Neostigmine; Rats; Rats, Sprague-Dawley; Serotonin 5-HT4 Receptor Agonists; Serotonin Receptor Agonists

Tegaserod is a first-in class selective serotonin 4 receptor agonist approved for the treatment of irritable bowel syndrome. In March 2007, the US Food and Drug Administration (FDA) suspended its use citing increased cardiovascular (CV) events in clinical trials. However, there is no known mechanistic basis for an adverse CV effect. To reassess the CV safety of tegaserod, teagaserod-treated patients (pts) in the Intermountain Healthcare database were identified (n = 2603), matched 1:6 with untreated (n = 15,618) patients by age, sex, and date of tegaserod initiation, and followed for an average of 2.5 years. Age averaged 38.6 +/- 13.5 years, and 94% were female. Cardiovascular event rates were low and similar in patients treated with tegaserod and matched untreated patients. For the primary composite CV endpoint, 54 (0.35%) untreated and 12 (0.46%) treated pts had an event (treated OR = 1.27, 95% CI: 0.68-2.38, P =.46), with 7 and 0 events, respectively, occurring within 3 months. A total of 12 (0.1%) untreated and 1 (<0.1%) treated pts were hospitalized for a myocardial infarction (MI). 36 (0.2%) untreated and 10 (0.4%) treated pts for a cardiovascular accident, and 1 pt in each group for unstable angina. A total of 6 (<0.1%) untreated and no treated pts died from cardiac causes. Event rates were comparable to expected rates in this population of mostly premenopausal women. This large epidemiologic study failed to confirm a reported large event differential for tegaserod that was noted incidentally in a clinical trials database, suggesting that the prior observation may have been due to chance.

Topics: Adult; Cardiovascular Diseases; Case-Control Studies; Databases as Topic; Female; Gastrointestinal Agents; Humans; Indoles; Irritable Bowel Syndrome; Logistic Models; Male; Middle Aged; Odds Ratio; Prospective Studies; Risk Assessment; Risk Factors; Serotonin 5-HT4 Receptor Agonists; Serotonin Receptor Agonists; Time Factors

Tegaserod, a 5-HT(4) receptor agonist, has been used to treat idiopathic constipation and constipation-predominant irritable bowel disease. It has recently been suggested that tegaserod has an affinity for 5-HT(1B) receptors, which mediate vasoconstriction. As some patients have experienced cardiac ischemia during treatment with tegaserod, we assessed contractions to tegaserod in healthy and diseased human isolated coronary arteries and compared the results with those obtained using sumatriptan, an established 5-HT(1B) receptor agonist. Proximal and distal human coronary arteries were divided into sets of healthy and diseased tissues based on functional endothelial responses. Concentration-response curves to tegaserod and sumatriptan were constructed to assess their contractile potential. Tegaserod's antagonist properties at 5-HT(1B) receptors were studied by constructing concentration-response curves to sumatriptan in the absence or presence of tegaserod (1 microM). Sumatriptan induced concentration-dependent contractions, which were greater in distal than in proximal coronary artery segments. In the proximal segments, tegaserod induced contractions only at concentrations of 10 microM or higher, while in distal segments contractions were generally absent. Tegaserod did not antagonize sumatriptan-induced contractions. There was no difference between the results obtained in healthy and diseased coronary arteries. In conclusion, tegaserod induced contractions in human proximal coronary arteries at concentrations 1000 times higher than C(max) (6 mg bid). Hence, tegaserod does not exhibit a relevant vasoconstrictor potential in the human coronary artery. Further, tegaserod did not behave as an antagonist at 5-HT(1B) receptors. Additional studies may be warranted to investigate the use of 5-HT(4) agonists in patients with cardiovascular risk factors.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Adolescent; Adult; Benzamides; Coronary Vessels; Female; Humans; In Vitro Techniques; Indoles; Male; Middle Aged; Muscle Contraction; Pyridines; Receptors, Serotonin, 5-HT4; RNA, Messenger; Serotonin 5-HT4 Receptor Agonists; Serotonin Receptor Agonists; Sumatriptan; Vasoconstrictor Agents; Young Adult

Although the mature enteric nervous system (ENS) has been shown to retain stem cells, enteric neurogenesis has not previously been demonstrated in adults. The relative number of enteric neurons in wild-type (WT) mice and those lacking 5-HT(4) receptors [knock-out (KO)] was found to be similar at birth; however, the abundance of ENS neurons increased during the first 4 months after birth in WT but not KO littermates. Enteric neurons subsequently decreased in both WT and KO but at 12 months were significantly more numerous in WT. We tested the hypothesis that stimulation of the 5-HT(4) receptor promotes enteric neuron survival and/or neurogenesis. In vitro, 5-HT(4) agonists increased enteric neuronal development/survival, decreased apoptosis, and activated CREB (cAMP response element-binding protein). In vivo, in WT but not KO mice, 5-HT(4) agonists induced bromodeoxyuridine incorporation into cells that expressed markers of neurons (HuC/D, doublecortin), neural precursors (Sox10, nestin, Phox2b), or stem cells (Musashi-1). This is the first demonstration of adult enteric neurogenesis; our results suggest that 5-HT(4) receptors are required postnatally for ENS growth and maintenance.

Topics: Adult Stem Cells; Aging; Animals; Apoptosis; Cell Proliferation; Cell Survival; Cells, Cultured; Cyclic AMP Response Element-Binding Protein; Enteric Nervous System; Gastrointestinal Tract; Indoles; Mice; Mice, Knockout; Neurogenesis; Neurons; Phosphorylation; Receptors, Serotonin, 5-HT4; Serotonin 5-HT4 Receptor Agonists; Serotonin Receptor Agonists; Sulfonamides

The in vitro pharmacological profile of TD-5108, a novel, selective 5-HT(4) receptor agonist, was compared to that of clinically efficacious gastroprokinetic 5-HT(4) receptor agonists. TD-5108 produced an elevation of cyclic adenosine monophosphate in human embryonic kidney 293 cells expressing the human recombinant 5-HT(4(c)) (h5-HT(4(c))) receptor (pEC(50) = 8.3) and 5-HT(4) receptor-mediated relaxation of the rat esophagus (pEC(50) = 7.9) and contraction of the guinea pig colon (pEC(50) = 7.9). In all in vitro assays, TD-5108 was a high intrinsic activity agonist, unlike tegaserod, mosapride, and cisapride which, in the majority of test systems, had lower intrinsic activity. TD-5108 had high affinity (pK (i) = 7.7) and selectivity (> or =25-fold) for h5-HT(4(c)) receptors over other biogenic amine receptors. TD-5108 was >500-fold selective over other 5-HT receptors (including h5-HT(2B) and h5-HT(3A)) and, at 3 microM, had no effect on human ether-à-go-go-related gene K+ channels. In conclusion, TD-5108 is a selective 5-HT(4) receptor agonist in vitro. The high intrinsic activity and preferential binding of TD-5108 to 5-HT4 over other 5-HT receptors may result in an improved clinical profile for the treatment of gastrointestinal disorders of reduced motility.

Topics: Animals; Azabicyclo Compounds; Benzamides; Cell Line; Cisapride; Colon; Cyclic AMP; Esophagus; Ether-A-Go-Go Potassium Channels; Guinea Pigs; Humans; Indoles; Kidney; Morpholines; Protein Binding; Rats; Receptors, Serotonin, 5-HT4; Serotonin 5-HT4 Receptor Agonists; Serotonin Receptor Agonists

The in vivo preclinical pharmacodynamic profile of TD-5108, a selective 5-HT(4) receptor agonist with high intrinsic activity, was compared to that of the clinically studied gastrointestinal pro-kinetic agents, tegaserod, cisapride and mosapride. The activity of TD-5108 was evaluated in guinea pig colonic transit, rat oesophageal relaxation and dog gastrointestinal smooth muscle contractility models. Subcutaneous administration of TD-5108, tegaserod, cisapride and mosapride increased guinea pig colonic transit (rank order of potencies: TD-5108 > tegaserod > cisapride > mosapride). Following intravenous and intraduodenal dosing, TD-5108, tegaserod, cisapride and mosapride produced dose-dependent relaxation of the rat oesophagus. On a molar basis, TD-5108 was approximately twofold less potent than tegaserod following intravenous dosing but 6- or 86-fold more potent than cisapride or mosapride, respectively, and 9- or 18-fold more potent than tegaserod or cisapride, respectively, after intraduodenal administration. Orally dosed TD-5108 increased the contractility of the canine antrum, duodenum and jejunum with higher potency than tegaserod. The selective 5-HT(4) receptor agonist, TD-5108, demonstrates robust in vivo activity in the guinea pig, rat and dog gastrointestinal tracts.

Topics: Administration, Oral; Animals; Azabicyclo Compounds; Benzamides; Cisapride; Colon; Dogs; Dose-Response Relationship, Drug; Esophagus; Female; Gastrointestinal Transit; Guinea Pigs; Indoles; Male; Morpholines; Muscle Contraction; Muscle, Smooth; Rats; Rats, Sprague-Dawley; Serotonin 5-HT4 Receptor Agonists; Serotonin Receptor Agonists

5-HT(4) receptor agonists are used therapeutically to treat disorders of reduced gastrointestinal motility. Since such compounds are evaluated in guinea-pigs, we cloned, expressed and pharmacologically characterized the guinea-pig 5-HT(4) and human 5-HT(4(b)) splice variant, which share 95% homology. The functional properties of guinea-pig 5-HT(4(b)) receptors were compared with native receptors in guinea-pig colon.. Membrane radioligand binding and whole cell cAMP accumulation assays were used to determine the affinities, potencies and intrinsic activities (IA). Contraction of the guinea-pig distal colon longitudinal muscle myenteric plexus preparation (LMMP) was monitored to evaluate functional activity.. pK(i) values for guinea-pig and human recombinant receptors, and guinea-pig striatum 5-HT(4) receptors, were in agreement, as were the potency and IA values for guinea-pig and human 5-HT(4) receptors expressed at a similar density ( approximately 0.2 pmol mg(-1) protein). Tegaserod was a potent (pEC(50)=8.4 and 8.7, respectively), full agonist at both guinea-pig and human 5-HT(4) receptors. In contrast, in the LMMP preparation, tegaserod was a potent, partial agonist (pEC(50)=8.2; IA=66%).. Close agreement between the pharmacological properties of guinea-pig and human 5-HT(4) receptors support the use of guinea-pig model systems for the identification of 5-HT(4) receptor therapeutics. However, the mechanisms underlying the different agonist properties of tegaserod in recombinant and isolated tissue preparations, and the extent to which these impact the clinical efficacy of tegaserod as a prokinetic agent, remain to be determined.

Topics: Alternative Splicing; Animals; Base Sequence; Colon; Digestive System; DNA Primers; Gastrointestinal Agents; Guinea Pigs; Humans; In Vitro Techniques; Indoles; Male; Receptors, Serotonin, 5-HT4; Recombinant Proteins; RNA, Messenger; Serotonin 5-HT4 Receptor Agonists; Serotonin Receptor Agonists

Topics: Drug Approval; Drug Industry; Humans; Indoles; Irritable Bowel Syndrome; Risk Assessment; Serotonin 5-HT4 Receptor Agonists; United States; United States Food and Drug Administration

1.--In this study, we aimed to characterize in vitro the effects of the benzofuran 5-HT(4) receptor agonists prucalopride, R149402 and R199715 and the indolic agents tegaserod and 5-HT in the atria of young pigs (10-11 weeks) and newborn piglets. 2.--In the paced left atrium of young pigs, only 5-HT results in positive inotropic responses when administered cumulatively (maximal effect relative to isoprenaline=53%, pEC(50)=6.8); however, all agonists showed lusitropic effects. Noncumulative administration results in greater positive inotropic responses for 5-HT and induces moderate positive inotropic responses for the other agonists; these responses fade. 3.--Phosphodiesterase (PDE) enzyme inhibition with 3-isobutyl-1-methylxanthine (IBMX; 20 microM) enhances the responses to cumulatively administered 5-HT (maximal effect=89%, pEC(50)=7.7) and reveals clear positive inotropic effects for prucalopride, tegaserod, R149402 and R199715; fading is abolished. The maximal effect of the benzofurans is less pronounced than that of the indoles. 4.--In the spontaneously beating right atrium of young pigs, all agonists show chronotropic activity when administered cumulatively in the absence of IBMX, without fade. Benzofurans behaved as partial agonists compared to 5-HT (maximal effect=54%, pEC(50)=6.5). 5.--In newborns, the inotropic activity of the agonists in the IBMX-treated left atrium was less pronounced than in the young pig; the same applied for the chronotropic response in the right atrium, except for 5-HT. 6.--In conclusion, the atrial responses to 5-HT(4) receptor activation increase in the first months of life; the inotropic response is regulated by PDEs. Prucalopride, R149402 and R199715 are partial agonists compared to 5-HT.

Topics: Animals; Animals, Newborn; Benzamides; Benzofurans; Heart Atria; Heart Rate; In Vitro Techniques; Indoles; Myocardial Contraction; Myocardium; Phosphodiesterase Inhibitors; Phosphoric Diester Hydrolases; Receptors, Serotonin, 5-HT4; Serotonin; Serotonin 5-HT4 Receptor Agonists; Sinoatrial Node; Stimulation, Chemical; Swine

The 5-HT4 receptor agonist and gastroprokinetic, tegaserod, possesses 5-HT2B receptor antagonist activity. However, the relevance of such activity is unclear. In this study, the 5-HT2B receptor antagonist and 5-HT4 agonist activities of tegaserod were investigated. Two piezoelectric crystals were implanted on the stomach fundus or oesophagus of anaesthetized Sprague-Dawley rats. Measurement of the transmission time of ultrasonic pulses between the implanted crystals provided a continuous record of inter-crystal distance, and thus of muscle length. In the stomach fundus, tegaserod (1 and 3 mg kg(-1)), administered subcutaneously (s.c.), inhibited the contractile response evoked by the 5-HT2B receptor agonist, BW 723C86 (0.01-1 mg kg(-1) intravenously (i.v.)). SB 206553 (1 mg kg(-1) s.c.), a selective 5-HT2B/2C receptor antagonist, also inhibited the BW 723C86-mediated responses. In the rat oesophagus, tegaserod (0.001-0.3 mg kg(-1) i.v. or 0.003-3 mg kg(-1) s.c.) increased inter-crystal distance, consistent with smooth muscle relaxation; the responses were inhibited by the 5-HT4 antagonist, piboserod (0.1 mg kg(-1) s.c.). Data from this in vivo rat study are consistent with tegaserod-induced 5-HT4 receptor-mediated oesophageal relaxation, and antagonism of 5-HT2B receptor-mediated stomach fundus contraction. The clinical relevance of the 5-HT2B receptor antagonism of tegaserod remains to be determined.

Topics: Animals; Esophagus; Gastric Fundus; Gastrointestinal Agents; Indoles; Male; Muscle Contraction; Muscle, Smooth; Rats; Rats, Sprague-Dawley; Serotonin 5-HT2 Receptor Antagonists; Serotonin 5-HT4 Receptor Agonists; Serotonin Receptor Agonists

Previous studies have demonstrated mixed inhibitory and facilitatory effects of 5-hydroxytryptamine-4 (5-HT(4)) receptor agonists on electrical field stimulation (EFS)-induced responses in human isolated colon. Here we report three types of responses to EFS in human isolated colon circular muscle: monophasic cholinergic contraction during EFS, biphasic response (nitrergic relaxation during EFS followed by cholinergic contraction after termination of EFS) and triphasic response (cholinergic contraction followed by nitrergic relaxation during EFS and a tachykininergic contraction after EFS). The effects of two 5-HT(4) receptor agonists, prucalopride and tegaserod were then investigated on monophasic responses only. Each compound inhibited contractions during EFS in a concentration-dependent manner. In the presence of N(omega)-nitro-l-arginine methyl ester (l-NAME) however, prucalopride and tegaserod enhanced the contractions in a concentration-dependent manner. In strips where the tone was elevated with substance-P and treated with scopolamine, EFS-induced relaxations were enhanced by the two agonists. The above observed effects by the two agonists were abolished by 5-HT(4) receptor antagonist SB-204070. The two agonists did not alter the tone raised by substance-P in the presence of scopolamine and l-NAME and did not affect carbachol-induced contractions in the presence of tetrodotoxin. These results suggest that in the circular muscle of human colon, 5-HT(4) receptor agonists simultaneously facilitate the activity of neurones which release the inhibitory and excitatory neurotransmitters, nitric oxide and acetylcholine respectively.

Topics: Acetylcholine; Adult; Aged; Aged, 80 and over; Benzofurans; Colon; Dose-Response Relationship, Drug; Electric Stimulation; Enzyme Inhibitors; Female; Humans; Indoles; Male; Middle Aged; Muscarinic Antagonists; Muscle Contraction; Muscle Relaxation; Muscle, Smooth; Neurokinin-1 Receptor Antagonists; Neurotransmitter Agents; NG-Nitroarginine Methyl Ester; Nitric Oxide; Organ Culture Techniques; Receptors, Neurokinin-2; Receptors, Neurokinin-3; Scopolamine; Serotonin 5-HT4 Receptor Agonists; Substance P

Tegaserod, a potent partial agonist of the serotonin 5-HT4 receptor, is used to treat women with constipation-predominant irritable bowel syndrome. Since the drug's approval, the manufacturer has received infrequent although serious reports of diarrhea and ischemic colitis in patients taking the drug. These instances have led to a recent warning letter to physicians and a change in the prescription labeling of tegaserod. We describe the development of ischemic colitis in a woman who was treated with tegaserod and review the relationship among ischemic colitis, tegaserod use, and irritable bowel syndrome. Potential mechanisms involved in the occurrence of ischemic colitis in patients receiving tegaserod are also discussed.

Topics: Adult; Colitis, Ischemic; Female; Humans; Indoles; Irritable Bowel Syndrome; Serotonin 5-HT4 Receptor Agonists; Serotonin Receptor Agonists

Topics: Antidepressive Agents; Cisapride; Female; Humans; Indoles; Irritable Bowel Syndrome; Serotonin 5-HT3 Receptor Antagonists; Serotonin 5-HT4 Receptor Agonists; Serotonin Antagonists; Serotonin Receptor Agonists

Topics: Carbolines; Humans; Indoles; Irritable Bowel Syndrome; Polypharmacy; Serotonin 5-HT3 Receptor Antagonists; Serotonin 5-HT4 Receptor Agonists; Serotonin Antagonists; Serotonin Receptor Agonists