benzofurans and tasimelteon

Depression has become one of the most commonly prevalent neuropsychiatric disorders, and the main characteristics of depression are sleep disorders and melatonin secretion disorders caused by circadian rhythm disorders. Abnormal endogenous melatonin alterations can contribute to the occurrence and development of depression. However, molecular mechanisms underlying this abnormality remain ambiguous. The present review summarizes the mechanisms underlying the antidepressant effects of melatonin, which is related to its functions in the regulation of the hypothalamic-pituitary-adrenal axis, inhibition of neuroinflammation, inhibition of oxidative stress, alleviation of autophagy, and upregulation of neurotrophic, promotion of neuroplasticity and upregulation of the levels of neurotransmitters, etc. Also, melatonin receptor agonists, such as agomelatine, ramelteon, piromelatine, tasimelteon, and GW117, have received considerable critical attention and are highly implicated in treating depression and comorbid disorders. This review focuses on melatonin and various melatonin receptor agonists in the pathophysiology and treatment of depression, aiming to provide further insight into the pathogenesis of depression and explore potential targets for novel agent development.

Topics: Animals; Antidepressive Agents; Antioxidants; Benzofurans; Chronobiology Disorders; Cyclopropanes; Depression; Humans; Hypothalamo-Hypophyseal System; Indenes; Melatonin; Pituitary-Adrenal System; Receptors, Melatonin; Sleep Wake Disorders

Circadian rhythms oscillate throughout a 24-h period and impact many physiological processes and aspects of daily life, including feeding behaviors, regulation of the sleep-wake cycle, and metabolic homeostasis. Misalignment between the endogenous biological clock and exogenous light-dark cycle can cause significant distress and dysfunction, and treatment aims for resynchronization with the external clock and environment. This article begins with a brief historical context of progress in the understanding of circadian rhythms, and then provides an overview of circadian neurobiology and the endogenous molecular clock. Various tools used in the diagnosis of circadian rhythm sleep-wake disorders, including sleep diaries and actigraphy monitoring, are then discussed, as are the therapeutic applications of strategically timed light therapy, melatonin, and other behavioral and pharmacological therapies including the melatonin agonist tasimelteon. Management strategies towards each major human circadian sleep-wake rhythm disorder, as outlined in the current International Classification of Sleep Disorders - Third Edition, including jet lag and shift work disorders, delayed and advanced sleep-wake phase rhythm disorders, non-24-h sleep-wake rhythm disorder, and irregular sleep-wake rhythm disorder are summarized. Last, an overview of chronotherapies and the circadian dysregulation of neurodegenerative diseases is reviewed.

Topics: Benzofurans; Chronobiology Disorders; Circadian Rhythm; Cyclopropanes; Humans; Neurodegenerative Diseases

To investigate the efficacy of exogenous administration of melatonin and melatonin receptor agonists for the improvement of delirium, sleep, and other clinical outcomes of subjects in the intensive care unit (ICU). We carefully searched three electronic databases, i.e., Pubmed/Medline, Embase, and Cochrane library, to retrieve randomized controlled trials (RCTs) administrating melatonin or melatonin receptor agonists to adult subjects admitted to the ICU. Useful data such as the prevalence of delirium, duration of sleep, number of awakenings per night, duration of mechanical ventilation, and ICU stay as well as in-ICU mortality were extracted and pooled by using a random effect model. Eight RCTs were included in the qualitative analysis. Administration of exogenous melatonin and melatonin receptor agonists was associated with a trend towards elongated duration of sleep (pooled weighted mean difference/WMD = 0.43; 95% confidence intervals/CIs, - 0.02~0.88, p = 0.063) and could decrease the number of awakenings per night (pooled WMD = - 2.03; 95% CIs, - 3.83~- 0.22, p = 0.028). Meanwhile, participants in the treatment group showed a significantly reduced prevalence of delirium (pooled risk ratio/RR = 0.49; 95% CIs, 0.28~0.88, p = 0.017) and duration of ICU stay (pooled WMD = - 0.32; 95% CI, - 0.56~- 0.07, p = 0.002) in comparison with those in the control group. Exogenous administration of melatonin and melatonin receptor agonists could improve the sleep of subjects in the intensive care units, which may play an important role in decreasing the prevalence of delirium and shortening duration of ICU stay.

Topics: Adult; Benzofurans; Case-Control Studies; Correlation of Data; Cross-Sectional Studies; Cyclopropanes; Delirium; Hospital Mortality; Humans; Indenes; Intensive Care Units; Length of Stay; Melatonin; Randomized Controlled Trials as Topic; Receptors, Melatonin; Respiration, Artificial; Risk Factors; Sleep; Sleep Wake Disorders; Treatment Outcome; Wakefulness

Non-24-h sleep-wake disorder (non-24) is a circadian rhythm disorder occurring in 55-70% of totally blind individuals (those lacking conscious light perception) in which the 24-h biological clock (central, hypothalamic, circadian pacemaker) is no longer synchronized, or entrained, to the 24-h day. Instead, the overt rhythms controlled by the biological clock gradually shift progressively earlier or later (free run) in accordance with the clock's near-24-h period, resulting in a recurrent pattern of daytime hypersomnolence and night-time insomnia. Orally administered melatonin and the melatonin agonist tasimelteon have been shown to entrain (synchronize) the circadian clock, resulting in improvements in night-time sleep and daytime alertness. We review the basic principles of circadian rhythms necessary to understand and treat non-24. The time of melatonin or tasimelteon administration must be considered carefully. For most individuals, those with circadian periods longer than 24 h, low-dose melatonin should be administered about 6 h before the desired bedtime, while in a minority, those with circadian periods shorter than 24 h (more commonly female individuals and African-Americans), melatonin should be administered at the desired wake time. Small doses (e.g., 0.5 mg of melatonin) that are not soporific would thus be preferable. Administration of melatonin or tasimelteon at bedtime will entrain individuals with non-24 but at an abnormally late time, resulting in continued problems with sleep and alertness. To date, tasimelteon has only been administered 1 h before the target bedtime in patients with non-24. Issues of cost, dose accuracy, and purity may figure into the decision of whether tasimelteon or melatonin is chosen to treat non-24. However, there are no head-to-head studies comparing efficacy, and studies to date show comparable rates of treatment success (entrainment).

Topics: Benzofurans; Blindness; Circadian Clocks; Cyclopropanes; Humans; Melatonin; Sleep Wake Disorders

Geriatric patients often experience insomnia because of physiological and neurological changes that occur during the aging process. Use of benzodiazepines, nonbenzodiazepine hypnotics, and diphenhydramine for the treatment of insomnia pose an increased risk of cognitive impairment, falls, and fractures in this patient population. Therapeutic alternatives approved by the Food and Drug Administration include suvorexant, doxepin, ramelteon, and tasimelteon, which have shown efficacy and safety in various studies. This paper explores and outlines the available safety and efficacy data associated with these medications and reviews their potential place in therapy in treating insomnia in the geriatric population.

Topics: Aged; Aged, 80 and over; Azepines; Benzofurans; Cyclopropanes; Doxepin; Humans; Hypnotics and Sedatives; Indenes; Randomized Controlled Trials as Topic; Sleep Initiation and Maintenance Disorders; Triazoles

Tasimelteon (Hetlioz(®)) is a dual melatonin receptor agonist indicated for the treatment of Non-24-Hour Sleep-Wake Disorder (Non-24) (free-running disorder). In two randomized, double-masked, multicentre, phase III trials, totally blind individuals with Non-24 who received oral tasimelteon 20 mg once nightly were significantly more likely than those receiving placebo to entrain the circadian pacemaker (the SET trial) and maintain entrainment (the RESET trial). Sleep/wake parameters and functioning were also improved with tasimelteon. Oral tasimelteon was generally well tolerated in totally blind patients with Non-24. In conclusion, tasimelteon is a useful drug for the treatment of Non-24 in totally blind individuals.

Topics: Benzofurans; Cyclopropanes; Humans; Sleep; Sleep Disorders, Circadian Rhythm; Time Factors; Treatment Outcome; Visually Impaired Persons

Circadian rhythm sleep-wake disorders (CRSWDs) are characterized by persistent or recurrent patterns of sleep disturbance related primarily to alterations of the circadian rhythm system or the misalignment between the endogenous circadian rhythm and exogenous factors that affect the timing or duration of sleep. These disorders collectively represent a significant unmet medical need, with a total prevalence in the millions, a substantial negative impact on quality of life, and a lack of studied treatments for most of these disorders. Activation of the endogenous melatonin receptors appears to play an important role in setting the circadian clock in the suprachiasmatic nucleus of the hypothalamus. Therefore, melatonin agonists, which may be able to shift and/or stabilize the circadian phase, have been identified as potential therapeutic candidates for the treatment of CRSWDs. Currently, only one melatonin receptor agonist, tasimelteon, is approved for the treatment of a CRSWD: non-24-hour sleep-wake disorder (or non-24). However, three additional commercially available melatonin receptor agonists-agomelatine, prolonged-release melatonin, and ramelteon-have been investigated for potential use for treatment of CRSWDs. Data indicate that these melatonin receptor agonists have distinct pharmacologic profiles that may help clarify their clinical use in CRSWDs. We review the pharmacokinetic and pharmacodynamic properties of these melatonin agonists and summarize their efficacy profiles when used for the treatment of CRSWDs. Further studies are needed to determine the therapeutic potential of these melatonin agonists for most CRSWDs.

Topics: Acetamides; Benzofurans; Circadian Rhythm; Cyclopropanes; Dietary Supplements; Humans; Receptors, Melatonin; Sleep Wake Disorders

In January 2014, the US Food and Drug Administration approved tasimelteon (Hetlioz™), a melatonin-receptor agonist for the treatment of non-24-hour sleep-wake disorder. This article provides an overview of the mechanism of action, pharmacokinetic properties, as well as the clinical efficacy, safety, and tolerability of tasimelteon. Relevant information was identified through a comprehensive literature search of several databases using the key words tasimelteon, Non-24-hour Sleep-Wake disorder, Non-24, and melatonin. Further information was obtained from the tasimelteon package insert, fda.gov, clinicaltrials.gov, briefing materials provided by Vanda Pharmaceuticals, and posters from scientific meetings.

Topics: Benzofurans; Clinical Trials as Topic; Cyclopropanes; Humans; Receptors, Melatonin; Sleep Disorders, Circadian Rhythm; Treatment Outcome; United States; United States Food and Drug Administration

Tasimelteon (Hetlioz®), a melatonin receptor agonist, is the first, and, at the time of the publication, the only drug to be approved by the U.S. Food and Drug Administration (FDA) for the treatment of non-24-hour sleep-wake disorder (non-24). This circadian rhythm disorder occurs most commonly in blind individuals without light perception, and it results from their inability to entrain to the 24-hour photoperiod, although the indication does not specify a particular patient population. Non-24 is characterized by a persistent cycle of nighttime insomnia and daytime sleepiness, alternating with asymptomatic periods depending on an individual's degree of circadian rhythm synchronization with the photoperiod at any particular time. Phase II clinical trials in healthy individuals confirmed the circadian phase-shifting potential of tasimelteon. Phase III trials in totally blind subjects diagnosed with non-24 demonstrated the efficacy of tasimelteon in reducing both nighttime wakefulness and daytime napping. Physiologic monitoring revealed that tasimelteon resulted in a higher proportion of individuals becoming entrained to the 24-hour cycle compared with placebo. Safety assessments indicated that tasimelteon is well tolerated, with the most common adverse events being headache, alanine aminotransferase elevation, nightmares or unusual dreams, and upper respiratory or urinary tract infections. Tasimelteon is available as a capsule in a single 20-mg dose and it must be obtained through Vanda Pharmaceutical's HetliozSolutions program with dispensing through a specialty pharmacy. Safety studies in blind individuals diagnosed with non-24 are ongoing and a future clinical trial with Smith-Magenis syndrome patients is planned.

Topics: Activity Cycles; Animals; Benzofurans; Blindness; Cyclopropanes; Drug Interactions; Humans; Receptors, Melatonin; Signal Transduction; Sleep; Sleep Disorders, Circadian Rhythm; Time Factors; Treatment Outcome; Wakefulness

Bipolar disorders (BD) present with abnormalities of circadian rhythmicity and sleep homeostasis, even during phases of remission. These abnormalities are linked to the underlying neurobiology of genetic susceptibility to BD. Melatonin is a pineal gland secreted neurohormone that induces circadian-related and sleep-related responses. Exogenous melatonin has demonstrated efficacy in treating primary insomnia, delayed sleep phase disorder, improving sleep parameters and overall sleep quality, and some psychiatric disorders like autistic spectrum disorders. In order to evaluate the efficacy of melatonin among patients with BD, this comprehensive review emphasizes the abnormal melatonin function in BD, the rationale of melatonin action in BD, the available data about the exogenous administration of melatonin, and melatonin agonists (ramelteon and tasimelteon), and recommendations of use in patients with BD. There is a scientific rationale to propose melatonin-agonists as an adjunctive treatment of mood stabilizers in treating sleep disorders in BD and thus to possibly prevent relapses when administered during remission phases. We emphasized the need to treat insomnia, sleep delayed latencies and sleep abnormalities in BD that are prodromal markers of an emerging mood episode and possible targets to prevent future relapses. An additional interesting adjunctive therapeutic effect might be on preventing metabolic syndrome, particularly in patients treated with antipsychotics. Finally, melatonin is well tolerated and has little dependence potential in contrast to most available sleep medications. Further studies are expected to be able to produce stronger evidence-based therapeutic guidelines to confirm and delineate the routine use of melatonin-agonists in the treatment of BD.

Topics: Antipsychotic Agents; Benzofurans; Bipolar Disorder; Circadian Rhythm; Cyclopropanes; Humans; Inappropriate Prescribing; Indenes; Melatonin; Off-Label Use; Patient Safety; Practice Patterns, Physicians'; Receptors, Melatonin; Risk Assessment; Risk Factors; Sleep; Treatment Outcome

Tasimelteon, a novel circadian regulator, is the first product for the treatment of Non-24-hour Sleep-Wake Disorder (Non-24) approved by either the FDA or the European Medicines Agency (EMA). Tasimelteon is a potent and specific melatonin (MT1 and MT2) receptor agonist with 2 - 4 times greater affinity for the MT2 receptor.. Safety was assessed in two controlled and two open-label studies in blind individuals with Non-24 and in two controlled studies of primary insomnia. Periodic assessments included collection of adverse events (AEs), laboratory testing, electrocardiograms (ECGs), vital sign monitoring, physical examinations and assessment for the potential for suicide. One study included additional assessments for endocrine function.. A total of 184 blind individuals with Non-24 received tasimelteon nightly with a median exposure > 1 year. In placebo-controlled studies, 387 patients with insomnia and 42 patients with Non-24 received tasimelteon nightly for 4 - 26 weeks. The total patient years exposure for the six studies assessed here is 258.64 patient years. Discontinuations due to AEs were similar across treatment groups. Overall in the clinical studies described here, AEs attributable to tasimelteon treatment were headache, diarrhea, dry mouth, alanine aminotransferase increased, somnolence, dizziness and nightmare/abnormal dreams. There were no clinically significant differences in treatment group with ECGs, vital signs, withdrawal, endocrine function and suicidality assessments.. Long-term tasimelteon administration was safe and well-tolerated. This is supported by placebo-controlled data in both Non-24 and insomnia patients.

Topics: Benzofurans; Cyclopropanes; Humans; Receptor, Melatonin, MT1; Receptor, Melatonin, MT2; Sleep Disorders, Circadian Rhythm; Sleep Initiation and Maintenance Disorders; Time Factors

Tasimelteon (HETLIOZ™) is an orally bioavailable agonist of the melatonin MT1 and MT2 receptors that has been approved in the US for the treatment of non-24-hour sleep-wake disorder. It is the first US FDA-approved medication for this orphan indication. Melatonin is thought to play a role in governing the body's natural sleep-wake cycle through physiological processes regulated in the suprachiasmatic nucleus of the hypothalamus. The hormone is secreted by the pineal gland, with onset typically occurring when daylight begins to dim. In healthy, sighted individuals, the endogenous circadian period is a little over 24 hours, but is entrained to the 24-hour day through exposure to environmental cues, such as light and darkness. In the absence of these cues, synchronisation is lost and the circadian rhythm follows the intrinsic non-24-hour clock, resulting in disorders like non-24-hour sleep-wake disorder. Because the rhythm of endogenous melatonin is considered to be a measure of the human circadian phase, the carefully timed administration of melatonin analogues, such as tasimelteon, can potentially promote circadian readjustment. This article summarizes the milestones in the development of tasimelteon leading to this first approval for the treatment of non-24-hour sleep-wake disorder.

Topics: Administration, Oral; Benzofurans; Cyclopropanes; Drug Approval; Drug Chronotherapy; Humans; Patents as Topic; Receptor, Melatonin, MT1; Receptor, Melatonin, MT2; Sleep Disorders, Circadian Rhythm; United States; United States Food and Drug Administration

Delayed sleep phase disorder is the most common of the circadian rhythm sleep disorders. Its treatment involves exploiting the intrinsic biological properties of the circadian pacemaker to advance biological rhythms, most notably the sleep-wake cycle, to a time which affords the individual an appropriate sleep opportunity compatible with normal societal functioning. This review highlights several new studies published in the last 18 months concerning sleep and circadian physiology relevant to the disorder and its management.. In addition to new information regarding the epidemiology and associations of the disorder, the pathophysiological importance of light exposure across the entire day, with special relevance to the phase-delaying effects of artificial evening light, is being unravelled. Furthermore, disorder-specific differences in period length and sleep homeostasis are being considered as pathophysiological contributors to delayed sleep phase disorder. The molecular effects of chronic sleep deprivation and circadian misalignment are currently being explored as potential mechanistic markers of the deleterious health consequences associated with these states.. Advances in our understanding of the dynamics of circadian physiology, sleep-wake regulation and the deleterious effects of misalignment and sleep deprivation, are spurring on efforts to find optimal treatment paradigms for patients presenting to sleep clinics with delayed sleep phase disorder.

Topics: Benzofurans; Circadian Rhythm; Cyclopropanes; Environmental Exposure; Homeostasis; Humans; Light; Melatonin; Period Circadian Proteins; Photoreceptor Cells; Receptors, Melatonin; Sleep Deprivation; Sleep Disorders, Circadian Rhythm

To examine the efficacy of tasimelteon for the treatment of non-24-hour sleep-wake disorder using evidence from controlled clinical trials.. Citations in Google Scholar and PubMed from January 1, 2008, to May 31, 2014, were identified using tasimelteon as the search term.. Results were limited to human trials published in English. Trials that compared tasimelteon with placebo were included.. A phase II trial (n = 39) evaluated the effects of tasimelteon versus placebo on improvements in sleep efficiency and the ability to shift circadian rhythms over 3 days. Significant shifts in circadian rhythm were only observed for 100-mg tasimelteon. A phase III trial (n = 412) evaluated the effects of tasimelteon versus placebo on assessment of latency to persistent sleep and wake after sleep onset; significant advantages were observed in tasimelteon recipients. The SET (Safety and Efficacy of Tasimelteon) trial (n = 84) enrolled blind men and women with Non-24. They received placebo or tasimelteon 20 mg daily. Tasimelteon recipients had significantly (P = 0.0025) better entrainment and N24CRS scores. The RESET (Randomized Withdrawal Study of the Efficacy and Safety of Tasimelteon) trial (n = 20) enrolled entrained participants from the SET trial who received 20 mg of tasimelteon or placebo daily for 8 weeks. The primary objective was to evaluate the maintenance of effect of tasimelteon to entrain circadian rhythms. Tasimelteon was associated with significantly (P = 0.0055) greater entrainment than placebo.. Tasimelteon improves sleep initiation and maintenance in patients with Non-24 who have a shift in endogenous circadian rhythms. However, the cost of this agent limits its use.

Topics: Benzofurans; Circadian Rhythm; Clinical Trials, Phase II as Topic; Clinical Trials, Phase III as Topic; Cyclopropanes; Humans; Randomized Controlled Trials as Topic; Receptors, Melatonin; Sleep; Sleep Initiation and Maintenance Disorders

Several melatonin receptors agonists (ramelteon, prolonged-release melatonin, agomelatine and tasimelteon) have recently become available for the treatment of insomnia, depression and circadian rhythms sleep-wake disorders. The efficacy and safety profiles of these compounds in the treatment of the indicated disorders are reviewed. Accumulating evidence indicates that sleep-wake disorders and co-existing medical conditions are mutually exacerbating. This understanding has now been incorporated into the new Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5). Therefore, when evaluating the risk/benefit ratio of sleep drugs, it is pertinent to also evaluate their effects on wake and comorbid condition. Beneficial effects of melatonin receptor agonists on comorbid neurological, psychiatric, cardiovascular and metabolic symptomatology beyond sleep regulation are also described. The review underlines the beneficial value of enhancing physiological sleep in comorbid conditions.

Topics: Acetamides; Animals; Benzofurans; Clinical Trials as Topic; Cyclopropanes; Humans; Hypnotics and Sedatives; Indenes; Melatonin; Neurodegenerative Diseases; Receptors, Melatonin; Sleep Wake Disorders

Many individuals with total blindness can develop a circadian rhythm disorder-called non-24 sleep wake syndrome-because they cannot detect light to resynchronize their sleep-wake cycles. A new melatonin 1 and melatonin 2 agonist tasimelteon improves sleep in these patients, resetting their circadian sleep-wake clocks.

Topics: Benzofurans; Blindness; Cyclopropanes; Humans; Receptors, Melatonin; Sleep Disorders, Circadian Rhythm

The various physiological actions of the neurohormone melatonin are mediated mainly by two G-protein-coupled MT(1) and MT(2) receptors. The melatoninergic drugs on the market, ramelteon and agomelatine, as well as the most advanced drug candidates under clinical evaluation, tasimelteon and PD-6735, are high-affinity nonselective MT(1) and MT(2) agonists. However, exploring the exact physiological role of the MT(1) and MT(2) melatonin receptors requires subtype selective MT(1) and MT(2) ligands. This review covers novel melatoninergic agonists and antagonists published since 2010, focusing on high-affinity and subtype selective agents. Additionally, compounds not mentioned in the previous review articles and ligands selective for the MT(3) binding site are included.

Topics: Acetamides; Animals; Benzofurans; Cyclopropanes; Humans; Indenes; Molecular Structure; Receptors, Melatonin; Structure-Activity Relationship

Current pharmacological treatment of insomnia involves the use of sedative-hypnotic benzodiazepine and non-benzodiazepine drugs. Although benzodiazepines improve sleep, their multiple adverse effects hamper their application. Adverse effects include impairment of memory and cognitive functions, next-day hangover and dependence. Non-benzodiazepines are effective for initiating sleep but are not as effective as benzodiazepines for improving sleep quality or efficiency. Furthermore, their prolonged use produces adverse effects similar to those observed with benzodiazepines. Inasmuch as insomnia may be associated with decreased nocturnal melatonin, administration of melatonin is a strategy that has been increasingly used for treating insomnia. Melatonin can be effective for improving sleep quality without the adverse effects associated with hypnotic-sedatives. Ramelteon, a synthetic analog of melatonin which has a longer half life and a stronger affinity for MT1 and MT2 melatonergic receptors, has been reportedly effective for initiating and improving sleep in both adult and elderly insomniacs without showing hangover, dependence, or cognitive impairment. Insomnia is also a major complaint among patients suffering from depressive disorders and is often aggravated by conventional antidepressants especially the specific serotonin reuptake inhibitors. The novel antidepressant agomelatine, a dual action agent with affinity for melatonin MT1 and MT2 receptors and 5-HT2c antagonistic properties, constitutes a new approach to the treatment of major depressive disorders. Agomelatine ameliorates the symptoms of depression and improves the quality and efficiency of sleep. Taken together, the evidence indicates that MT1/MT2 receptor agonists like ramelteon or agomelatine may be valuable pharmacological tools for insomnia and for depression-associated insomnia.

Topics: Acetamides; Animals; Benzodiazepines; Benzofurans; Clinical Trials as Topic; Cyclopropanes; Depressive Disorder; Humans; Hypnotics and Sedatives; Indenes; Indoles; Melatonin; Sleep Initiation and Maintenance Disorders

Insomnia is a prevalent disorder with nearly 50% of the US adult population reporting insomnia symptoms during the past year and 10 - 15% reporting chronic insomnia. In addition, insomnia is a frequent comorbidity with depression, anxiety and pain, as well as other medical and psychiatric disorders. Tasimelteon is a melatonin receptor agonist developed by Bristol-Myers Squibb Co. and later licensed to Vanda Pharmaceuticals in 2004. It is being developed for the treatment of sleep disorders, including insomnia and mood disorders.. The nature and prevalence of insomnia are described in this review, along with the current pharmacological treatments for the disorder. Summaries of the available pharmacological and clinical data for tasimelteon are also provided. A Medline search using the terms tasimelteon, melatonin and insomnia was undertaken to assess the current literature on these topics.. While the few clinical trials of the medication have been promising, much more extensive testing, along with more detailed reporting of the drug's pharmacokinetics and pharmacodynamics, is needed before tasimelteon can be considered a worthwhile addition to the available treatments for insomnia. In particular, testing of the drug's effectiveness in treating maintenance insomnia, as well as tests of its long-term effectiveness and safety, is much needed.

Topics: Animals; Benzofurans; Clinical Trials as Topic; Cyclopropanes; Humans; Melatonin; Receptors, Melatonin; Sleep Initiation and Maintenance Disorders

The ability of melatonin to shift biological rhythms is well known. As a result, melatonin has been used in the treatment of various circadian rhythm sleep disorders, such as advanced and delayed sleep phase disorders, jet lag and shiftwork disorder. The current evidence for melatonin being efficacious in the treatment of primary insomnia is less compelling. The development of agents that are selective for melatonin receptors provides opportunity to further elucidate the actions of melatonin and its receptors and to develop novel treatments for specific types of sleep disorders. The agonists reviewed here - ramelteon, tasimelteon and agomelatine - all appear to be efficacious in the treatment of circadian rhythm sleep disorders and some types of insomnia. However, further studies are required to understand the mechanisms of action, particularly for insomnia. Clinical application of the agonists requires a good understanding of their phase-dependent properties. Long-term effects of melatonin should be evaluated in large-scale, independent randomized controlled trials.

Topics: Acetamides; Animals; Benzofurans; Circadian Rhythm; Cyclopropanes; Humans; Hypnotics and Sedatives; Indenes; Melatonin; Sleep Initiation and Maintenance Disorders

Traveling through several time zones results in a constellation of symptoms known as jet lag. These include reduced alertness, daytime fatigue, loss of appetite, reduced cognitive skills, and disruption of the sleep/wake cycle. In susceptible air travel passengers, jet lag may exacerbate affective illness and result in psychiatric morbidity. Dysregulation of circadian rhythms and melatonin secretion represent the common underlying factor in jet lag and other circadian disorders. Recent studies have established the effectiveness of strategically timed administration of melatonin and appropriate timed exposure to environmental schedules including light in counteracting the dysregulation (chronobiologic actions). With the introduction of melatonergic agonists such as ramelteon and tasimelteon, which have both a stronger affinity for MT₁ and MT₂ melatonin receptors and a longer half-life, new therapeutic options now exist for treating the sleep disturbances associated with jet lag. The melatonin analogs are unique inasmuch as they can also enhance daytime alertness. The recently introduced melatonergic antidepressant agomelatine, which has established its supremacy over other antidepressants in having a significant chronobiologic activity, represents a good choice for treating depressive symptoms that are associated with jet lag.

Topics: Acetamides; Benzofurans; Central Nervous System Depressants; Cyclopropanes; Depressive Disorder; Humans; Indenes; Jet Lag Syndrome; Melatonin; Sleep Disorders, Circadian Rhythm

An impairment in next day driving performance has been reported for almost every drug currently United States Food and Drug Administration (FDA) approved for improvement of sleep in chronic and transient insomnia. Tasimelteon, a melatonin receptor agonist, demonstrated significant improvements in night-time sleep, daytime naps, and sleep timing in non-24-hr sleep-wake disorder (Non-24) by entraining these patients to a 24-hr day as measured by melatonin and cortisol rhythms. Given this new mechanism of action of entraining the biological clock, we conducted a study to evaluate the potential effect tasimelteon may have on the ability to operate a motor vehicle. The study was conducted in 48 healthy adult subjects using a randomised, double-blind, placebo and active (zopiclone 7.5 mg) controlled study with a 3-period cross-over design. Driving performance was assessed by measuring standard deviation of lateral position (SDLP) using the validated Cognitive Research Corporation Driving Simulator-MiniSim. The difference in least square mean SDLP for tasimelteon was 1.22 cm reflecting a non-significant increase in SDLP change from placebo (p = .1119). In contrast, treatment with the active control, zopiclone 7.5 mg, was associated with a meaningful and significant increase in SDLP, change from placebo for zopiclone was 4.14 cm (p < .0001). The lack of clinically meaningful and statistically significant finding with tasimelteon was further supported by the symmetry analysis, which showed the distribution of within-subject differences between tasimelteon and placebo was symmetric about zero. At the FDA-approved 20 mg dose to treat Non-24, tasimelteon did not impair next-day driving performance compared to placebo in adult healthy volunteers.

Topics: Adult; Automobile Driving; Benzofurans; Cross-Over Studies; Cyclopropanes; Double-Blind Method; Humans; Sleep; Sleep Initiation and Maintenance Disorders

To assess the efficacy of tasimelteon to improve sleep in Smith-Magenis syndrome (SMS).. A 9-week, double-blind, randomized, two-period crossover study was conducted at four US clinical centers. Genetically confirmed patients with SMS, aged 3 to 39, with sleep complaints participated in the study. Patients were assigned to treatment with tasimelteon or placebo in a 4-week crossover study with a 1-week washout between treatments. Eligible patients participated in an open-label study and were followed for >3 months.. Improvement of sleep quality (DDSQ50) and total sleep time (DDTST50) on the worst 50% of nights were primary endpoints. Secondary measures included actigraphy and behavioral parameters. Over three years, 52 patients were screened, and 25 patients completed the randomized portion of the study. DDSQ50 significantly improved over placebo (0.4, p = 0.0139), and DDTST50 also improved (18.5 minutes, p = 0.0556). Average sleep quality (0.3, p = 0.0155) and actigraphy-based total sleep time (21.1 minutes, p = 0.0134) improved significantly, consistent with the primary outcomes. Patients treated for ≥90 days in the open-label study showed persistent efficacy. Adverse events were similar between placebo and tasimelteon.. Tasimelteon safely and effectively improved sleep in SMS.

Topics: Adolescent; Adult; Benzofurans; Child; Child, Preschool; Cross-Over Studies; Cyclopropanes; Double-Blind Method; Humans; Sleep; Smith-Magenis Syndrome; Treatment Outcome; Young Adult

Tasimelteon is a circadian regulator that resets the master clock in the suprachiasmatic nuclei of the hypothalamus by binding to both melatonin MT1 and MT2 receptors making it a dual melatonin receptor agonist. Tasimelteon has been approved by the United States Food and Drug Administration for the treatment of Non-24-Hour Sleep-Wake Disorder (Non-24). Two prospective, single-center, open-label studies evaluated the pharmacokinetics of tasimelteon and its main metabolites after a single 20 mg dose administered to subjects with mild or moderate hepatic impairment or severe renal impairment, including subjects on dialysis compared to healthy controls. In subjects with mild or moderate hepatic impairment, exposure to tasimelteon after a single 20 mg dose, as measured by area under the plasma concentration-time curve to infinity, was increased by approximately 2-fold. There was no apparent relationship between tasimelteon clearance and renal function. No safety concerns were apparent in either study. Based on these results, the changes in the pharmacokinetics of tasimelteon due to mild or moderate hepatic or severe renal impairment are not considered clinically relevant, and no dose adjustment is necessary in these patients.

Topics: Adolescent; Adult; Aged; Area Under Curve; Benzofurans; Cyclopropanes; Female; Half-Life; Humans; Liver Diseases; Male; Metabolic Clearance Rate; Middle Aged; Receptors, Melatonin; Renal Dialysis; Renal Insufficiency; Severity of Illness Index; Sleep Disorders, Circadian Rhythm; United States; Young Adult

Most totally blind people have non-24-hour sleep-wake disorder (non-24), a rare circadian rhythm disorder caused by an inability of light to reset their circadian pacemaker. In two consecutive placebo-controlled trials (SET and RESET), we assessed safety and efficacy (in terms of circadian entrainment and maintenance) of once-daily tasimelteon, a novel dual-melatonin receptor agonist.. We undertook the placebo-controlled, randomised, double-masked trials in 27 US and six German clinical research centres and sleep centres. We screened totally blind adults (18-75 years of age), who were eligible for the randomisation phase of SET if they had a non-24-hour circadian period (τ) of 24·25 h or longer (95% CI greater than 24·0 and up to 24·9 h), as calculated from measurements of urinary 6-sulphatoxymelatonin rhythms. For SET, we used block randomisation to assign patients (1:1) to receive tasimelteon (20 mg) or placebo every 24 h at a fixed clock time 1 h before target bedtime for 26 weeks. Patients who entered the open-label group receiving tasimelteon in SET or who did not meet the SET inclusion criteria but did meet the RESET inclusion criteria were screened for RESET. A subset of the patients who entered the open-label group before the RESET study and who had eligible τ values were screened for RESET after completing the open-label treatment. In RESET, we withdrew tasimelteon in a randomised manner (1:1) in patients who responded (ie, entrained) after a tasimelteon run-in period. Entrainment was defined as having τ of 24·1 h or less and a 95% CI that included 24·0 h. In SET, the primary endpoint was the proportion of entrained patients, assessed in the intention-to-treat population. The planned step-down primary endpoint assessed the proportion of patients who had a clinical response (entrainment at month 1 or month 7 plus clinical improvement, measured by the Non-24 Clinical Response Scale). In RESET, the primary endpoint was the proportion of non-entrained patients, assessed in the intention-to-treat population. Safety assessments included adverse events and clinical laboratory measures, assessed in all treated patients. These trials are registered with ClinicalTrials.gov, numbers NCT01163032 and NCT01430754.. Between Aug 25, 2010, and July 5, 2012, we screened 391 totally blind patients for SET, of whom 84 (22%) were assigned to receive tasimelteon (n=42) or placebo (n=42). Two patients in the tasimelteon group and four in the placebo group discontinued the study before τ was measured, due to adverse events, withdrawal of consent, and a protocol deviation. Circadian entrainment occurred in eight (20%) of 40 patients in the tasimelteon group compared with one (3%) of 38 patients in the placebo group at month 1 (difference 17%, 95% CI 3·2-31·6; p=0·0171). Nine (24%) of 38 patients showed a clinical response, compared with none of 34 in the placebo group (difference 24%, 95% CI 8·4-39·0; p=0·0028). Between Sept 15, 2011, and Oct 4, 2012, we screened 58 patients for eligibility in RESET, 48 (83%) of whom had τ assessed and entered the open-label tasimelteon run-in phase. 24 (50%) patients entrained, and 20 (34%) were enrolled in the randomisation phase. Two (20%) of ten patients who were withdrawn to placebo remained entrained compared with nine (90%) of ten who continued to receive tasimelteon (difference 70%, 95% CI 26·4-100·0; p=0·0026). No deaths were reported in either study, and discontinuation rates due to adverse events were comparable between the tasimelteon (3 [6%] of 52 patients) and placebo (2 [4%] of 52 patients) treatment courses. The most common side-effects associated with tasimelteon in SET were headache (7 [17%] of 42 patients given tasimelteon vs 3 [7%] of 42 patients given placebo), elevated liver enzymes (4 [10%] vs 2 [5%]), nightmares or abnormal dreams (4 [10%] vs none), upper respiratory tract infection (3 [7%] vs none], and urinary tract infections (3 [7%] vs 1 [2%]).. Once-daily tasimelteon can entrain totally blind people with non-24; however, continued tasimelteon treatment is necessary to maintain these improvements.. Vanda Pharmaceuticals.

Topics: Benzofurans; Blindness; Circadian Rhythm; Cyclopropanes; Double-Blind Method; Female; Humans; Male; Middle Aged; Receptors, Melatonin; Sleep Disorders, Circadian Rhythm; Treatment Outcome

Topics: Adult; Benzofurans; Chromatography, Liquid; Cyclopropanes; Humans; Limit of Detection; Linear Models; Liquid-Liquid Extraction; Male; Reproducibility of Results; Tandem Mass Spectrometry; Young Adult

Non-24-h sleep-wake rhythm disorder (non-24) is observed in approximately half of totally blind individuals, a condition caused by their circadian pacemaker in the suprachiasmatic nucleus not being entrained to 24 h due to a lack of light perceptions. These subjects have a progressively delayed circadian cycle each day, non-24 periodically inducing nighttime insomnia and daytime sleepiness. Tasimelteon is a dual melatonin receptor agonist with high affinity for the melatonin 2 receptor, and it entrains endogenous melatonin rhythms and sleep-wake cycles in individuals with non-24. Areas covered: Herein, the authors review the treatment of non-24 with tasimelteon. The authors further compare tasimelteon with other melatonin receptor agonists. Expert opinion: The treatment strategies for non-24 aim to resynchronize the free-running rhythm with the 24 h light-dark cycle. Tasimelteon entrains circadian rhythms and improves the sleep-wake functions of individuals with non-24. Furthermore, the RESET study demonstrated that 20% of patients that discontinued tasimelteon maintained circadian entrainment whereas 90% of those who continued it maintained circadian entrainment. Long-term administration of tasimelteon is safe and well tolerated, and it is the only pharmacological therapy approved by the US Food and Drug Administration and the European Medicines Agency for non-24.

Topics: Adolescent; Adult; Benzofurans; Cyclopropanes; Female; Humans; Male; Middle Aged; Receptors, Melatonin; Sleep Disorders, Circadian Rhythm; Young Adult

We present a totally blind adolescent with refractory insomnia due to a combination of Non-24 hour sleep-wake disorder and restless leg syndrome that was successfully treated with tasimelteon, iron replacement, and gabapentin. To our knowledge, this is the first published report of treatment of N24 with tasimelteon in an adolescent. In addition, this case highlights the importance of recognizing and treating multifactorial causes of insomnia.

Topics: Adolescent; Benzofurans; Blindness; Cyclopropanes; Drug Resistance; Drug Therapy, Combination; Female; Gabapentin; Humans; Iron; Restless Legs Syndrome; Sleep Disorders, Circadian Rhythm; Sleep Initiation and Maintenance Disorders

Two crystalline forms of tasimelteon, a drug approved by the U.S. Food and Drug Administration for the treatment of non-24-h sleep-wake disorder, have been studied by single crystal and powder diffraction analyses, thermogravimetric analysis, differential scanning calorimetry, spectroscopic, and optical methods. The synthetic method forming tasimelteon is described in detail, with its full analytical, spectroscopic, and enantiopurity characterization. Solid tasimelteon hemihydrate, C

Topics: Benzofurans; Calorimetry, Differential Scanning; Crystallization; Crystallography, X-Ray; Cyclopropanes; Melatonin; Particle Size; Powder Diffraction; Thermogravimetry; Water; X-Ray Diffraction

Two new crystal forms of tasimelteon TSM-I and TSM-II were reported here. Crystallization of crude in methanol or mixture solvent results in anhydrate crystal form (TSM-I) and hemihydrate crystal form (TSM-II) respectively. To the best of our knowledge, it is the first report about crystalline form of tasimelteon. The two crystal forms were exhaustively characterized by Scanning Electron Microscopy, Fourier Transform Infrared Spectroscopy, Raman Spectra, Differential Scanning Calorimetry, Thermogravimetric Analysis, Solid State NMR Spectroscopy and Powder X-ray diffraction and Single Crystal X-ray Diffraction. Furthermore, the pharmacokinetic behavior of TSM-I and TSM-II in rats were measured. We found that though TSM-II is considerably more soluble than TSM-I under water (pH = 7.0) and pH 1.2 buffer conditions, the bioavailability of TSM-Ivia oral administration was better compared to that of TSM-II.

Topics: Administration, Oral; Animals; Benzofurans; Biological Availability; Calorimetry, Differential Scanning; Chemistry, Pharmaceutical; Crystallization; Crystallography, X-Ray; Cyclopropanes; Drug Liberation; Hydrogen-Ion Concentration; Male; Mice; Mice, Inbred BALB C; Microscopy, Electron, Scanning; Receptors, Melatonin; Solubility; Spectrophotometry; Water

This is the fourth in a series of columns discussing the rational and targeted development of drugs to affect specific central nervous system (CNS) circuits in specific ways based on knowledge gained by molecular biology and the human genome project. The first column in this series described 6 CNS drugs with novel mechanisms of action developed over the last 25 years. The second column discussed differences between syndromic diagnoses as exemplified by the third through the fifth editions of the Diagnostic and Statistical Manual of Mental Disorders (DSM III through DSM-5) and the new approach to psychiatric diagnoses championed by the National Institute of Mental Health in their Research Domain Criteria Initiative. The third column reviewed the last 9 years of drug development contrasting the development of drugs in other therapeutic areas (eg, cancer) with psychiatric and related CNS-active drugs. This column extends the discussion of modern drug development for psychiatric and other CNS-related indications, using the development of tasimelteon as an example of how modern drug development focuses rationally on novel targets of interest while simultaneously achieving "specificity." Tasimelteon, which is indicated for the treatment of non-24-hour sleep-wake disorder, was developed to be a selective agonist at the melatonin MT1 and MT2 receptors, with limited or no effects at other pharmacologically relevant receptors and enzymes to minimize the potential for off-target effects (eg, nuisance side effects), toxicity, drug-drug interactions, and effects on oxidative drug metabolizing enzymes. The next column in this series will continue the discussion of the development of CNS drugs with novel mechanisms of action, using suvorexant, which targets orexin-1 and orexin-2 receptors, to illustrate the preclinical and human studies that were carried out to assess its safety as part of a successful new drug application.

Topics: Benzofurans; Central Nervous System Agents; Cyclopropanes; Drug Development; Drug Discovery; Humans; Molecular Targeted Therapy; Receptors, Melatonin; Sleep Disorders, Circadian Rhythm

Engineered hemoproteins have recently emerged as promising systems for promoting asymmetric cyclopropanations, but variants featuring predictable, complementary stereoselectivity in these reactions have remained elusive. In this study, a rationally driven strategy was implemented and applied to engineer myoglobin variants capable of providing access to 1-carboxy-2-aryl-cyclopropanes with high trans-(1R,2R) selectivity and catalytic activity. The stereoselectivity of these cyclopropanation biocatalysts complements that of trans-(1S,2S)-selective variants developed here and previously. In combination with whole-cell biotransformations, these stereocomplementary biocatalysts enabled the multigram synthesis of the chiral cyclopropane core of four drugs (Tranylcypromine, Tasimelteon, Ticagrelor, and a TRPV1 inhibitor) in high yield and with excellent diastereo- and enantioselectivity (98-99.9% de; 96-99.9% ee). These biocatalytic strategies outperform currently available methods to produce these drugs.

Topics: Adenosine; Benzofurans; Catalysis; Cyclopropanes; Escherichia coli; Molecular Structure; Myoglobin; Protein Engineering; Stereoisomerism; Ticagrelor; Tranylcypromine

Hetlioz(®) (tasimelteon) is the first approved treatment in the United States for Non-24-Hour Sleep-Wake Disorder (Non-24). We present here data on the in vitro binding affinity of tasimelteon for both human melatonin receptors MT1 and MT2, as well as the extended screen of other receptors and enzymes. Results indicate that tasimelteon is a potent Dual Melatonin Receptor Agonist (DMRA) with 2.1-4.4 times greater affinity for the MT2 receptor believed to mediate circadian rhythm phase-shifting (Ki = 0.0692 nM and Ki = 0.17 nM in NIH-3T3 and CHO-K1 cells, respectively), than for the MT1 receptor (Ki = 0.304 nM and Ki = 0.35 nM, respectively). Tasimelteon was also shown to have no appreciable affinity for more than 160 other pharmacologically relevant receptors and several enzymes.

Topics: Benzofurans; Cyclopropanes; Humans; Protein Binding; Receptors, Melatonin

Tasimelteon ([1R-trans]-N-[(2-[2,3-dihydro-4-benzofuranyl] cyclopropyl) methyl] propanamide), a novel dual melatonin receptor agonist that demonstrates specificity and high affinity for melatonin receptor types 1 and 2 (MT1 and MT2 receptors), is the first treatment approved by the US Food and Drug Administration for Non-24-Hour Sleep-Wake Disorder. Tasimelteon is rapidly absorbed, with a mean absolute bioavailability of approximately 38%, and is extensively metabolized primarily by oxidation at multiple sites, mainly by cytochrome P450 (CYP) 1A2 and CYP3A4/5, as initially demonstrated by in vitro studies and confirmed by the results of clinical drug-drug interactions presented here. The effects of strong inhibitors and moderate or strong inducers of CYP1A2 and CYP3A4/5 on the pharmacokinetics of tasimelteon were evaluated in humans. Coadministration with fluvoxamine resulted in an approximately 6.5-fold increase in tasimelteon's area under the curve (AUC), whereas cigarette smoking decreased tasimelteon's exposure by approximately 40%. Coadministration with ketoconazole resulted in an approximately 54% increase in tasimelteon's AUC, whereas rifampin pretreatment resulted in a decrease in tasimelteon's exposure of approximately 89%.

Topics: Adolescent; Adult; Area Under Curve; Benzofurans; Cyclopropanes; Cytochrome P-450 CYP1A2 Inhibitors; Cytochrome P-450 CYP3A Inducers; Cytochrome P-450 CYP3A Inhibitors; Drug Interactions; Female; Fluvoxamine; Half-Life; Humans; Ketoconazole; Male; Middle Aged; Molecular Structure; Receptors, Melatonin; Rifampin; Smoking; Young Adult

Topics: Antibodies, Monoclonal, Humanized; Benzhydryl Compounds; Benzofurans; Cyclopropanes; Diphosphates; Drug Approval; Drug Therapy; Glucagon-Like Peptide 1; Glucosides; Glycopeptides; Humans; Lactones; Lipoglycopeptides; Organophosphates; Oxazoles; Pyridines; Sulfates; Teicoplanin; United States; United States Food and Drug Administration

Topics: Benzofurans; Blindness; Circadian Rhythm; Cyclopropanes; Cytochrome P-450 CYP1A2; Humans; Receptors, Melatonin; Sleep Wake Disorders

Topics: Benzofurans; Cyclopropanes; Humans; Receptors, Melatonin; Sleep; Sleep Disorders, Circadian Rhythm; Treatment Outcome

Topics: Animals; Benzofurans; Circadian Rhythm; CLOCK Proteins; Cyclopropanes; Efficiency; Humans; Melatonin; Obesity; Sleep; Suprachiasmatic Nucleus

Tasimelteon, developed by Vanda Pharmaceuticals Inc under license from Bristol-Myers Squibb Co, is a melatonin receptor agonist. Because of the high density of melatonin receptors in the circadian pacemaker, the suprachiasmatic nucleus, melatonergic actions can phase-shift circadian rhythms and promote sleep. Tasimelteon was effective in reducing sleep onset latency (in phase II and III clinical trials) and in resetting the circadian melatonin rhythm (in phase II trials), which indicated its potential suitability as treatment for jet lag, shift work and circadian rhythm sleep disorders. Statistically significant improvements in sleep maintenance have also been observed with the drug. Tasimelteon has been claimed to be useful in the treatment of depression, and preclinical evidence in this respect is to be confirmed in a phase II clinical trial, which was ready to be initiated at the time of publication. It is plausible that the drug may be effective in the treatment of depressive disorders, at least those that are related to circadian dysfunction, and that it may attenuate sleep problems in depressed patients of different subtypes. A general suitability in mitigating other symptoms of major depressive disorder cannot be deduced from the actions of tasimelteon via the melatonin receptors MT1 and MT2. The drug is well tolerated, does not induce impairment of next-day functioning or dependence, and seems to be safe in short-term treatment; however, toxicological data would be required for assessing its long-term safety.

Topics: Animals; Benzofurans; Clinical Trials as Topic; Cyclopropanes; Drugs, Investigational; Humans; Melatonin; Molecular Structure; Patents as Topic; Receptors, Melatonin; Sleep Disorders, Circadian Rhythm; Sleep Initiation and Maintenance Disorders; Structure-Activity Relationship

The pineal hormone melatonin is able to shift the timing of circadian rhythms, including the sleep-wake cycle, and to promote sleep. Melatonin agonists with similar properties have therapeutic potential for the treatment of circadian rhythm sleep disorders. Depression is specifically targeted by agomelatine, which is also a serotonin-2C (5-HT(2C)) antagonist.

Topics: Acetamides; Benzofurans; Cyclopropanes; Drug Administration Schedule; Humans; Indenes; Melatonin; Receptors, Melatonin

TopCount, a microplate scintillation counter (MSC), has been recently employed as an off-line liquid radiochromatographic detector for radioactive metabolite profile analysis. The present study was undertaken to validate TopCount for metabolite profiling with respect to sensitivity, accuracy, precision and radioactivity recovery. Matrix effects of various human samples on TopCount performance and capability of MSC for volatile metabolite analysis were also investigated. TopCount had a limit of detection (LOD) of 5 DPM and a limit of quantification (LOQ) of 15 DPM for [(14)C]-labeled compounds at a 10min counting time. It was two-fold more sensitive than a liquid scintillation counter (LSC), and 50-100-fold more sensitive than a radioactivity flow detector (RFD). TopCount had comparable accuracy and precision to RFD, and comparable precision to LSC for determining relative abundance of metabolites. Human liver microsome incubation (up to 1 mL), plasma (up to 1 mL), urine (up to 2 mL) and feces (up to 50mg) had no significant quenching effects on TopCount performance. Benzoic acid, a volatile metabolite, was detected by TopCount, but not by Microbeta counter after microplates were dried under vacuum. Radioactivity recovery in HPLC-MSC analysis was reliably determined using an LSC-based method. Examples of using HPLC-MSC for analysis of low levels of radioactive metabolites are presented, including determination of plasma metabolite profile, in vitro reactive metabolites trapped by [(3)H]glutathione, and metabolite concentrations in an enzyme kinetic experiment. The data from this study strongly suggest that HPLC in combination with TopCount is a viable alternative analytical tool for detection and quantification of low levels of radioactive metabolites in biological fluids.

Topics: Animals; Benzofurans; Body Fluids; Buspirone; Chromatography, High Pressure Liquid; Cyclopropanes; Humans; Male; Rats; Rats, Sprague-Dawley; Scintillation Counting; Sensitivity and Specificity

BMS-214778 is a novel melatonin receptor agonist that may be a useful treatment for sleep disorders that result from disruption of circadian rhythms. Pharmacokinetic studies following intravenous and oral administration and 1 month oral steady-state studies were carried out in rats and monkeys. Rat brain was analyzed for BMS-214778 to determine the extent of its penetration from plasma. Equilibrium dialysis was employed to determine the extent of binding of [(14)C]-BMS-214778 to rat, monkey, and human sera proteins. In vitro metabolism studies with BMS-214778 in rat, monkey, and human liver homogenate preparations (S-9), with monkey and human liver slice preparations, and with pooled human liver microsomes were performed and the incubates analyzed for potential metabolites. Recombinant microsomes expressing specific human cytochrome P(450) (CYP) enzymes were employed to identify possible human metabolic pathways. BMS-214778 showed a high hepatic extraction and high degree of tissue distribution. BMS-214778 also displayed non-linear oral pharmacokinetics. Systemic exposures following oral doses in rats and monkeys increased more than proportionally to the increment in dose. Loss of systemic exposure to BMS-214778 upon chronic oral dosing was observed in male rats where exposure was one-half to two-thirds compared to a single dose, while modest decreases in exposure were observed upon chronic dosing in both sexes of monkey. This was suggestive of induction of BMS-214778 clearance and/or excretion mechanisms. BMS-214778 distributed from the plasma to brain in the rat (mean +/- SD brain:plasma ratio of 0.9 +/- 0.1, N = 3). [(14)C]-BMS-214778 was moderately bound to serum proteins (<91% bound) in all species examined. In vitro metabolism of BMS-214778 was mostly by hydroxylation and dehydrogenation, with CYP1A1, 1A2, 2D6, and 2C9 being the most likely isoforms to be involved in its metabolism in humans.

Topics: Administration, Oral; Animals; Area Under Curve; Benzofurans; Biological Availability; Blood Proteins; Blood-Brain Barrier; Brain; Cyclopropanes; Drug Evaluation, Preclinical; Female; Gas Chromatography-Mass Spectrometry; Half-Life; Humans; In Vitro Techniques; Injections, Intravenous; Liver; Macaca fascicularis; Male; Protein Binding; Rats; Rats, Sprague-Dawley; Receptors, Melatonin; Time Factors