A placebo-controlled evaluation of single, escalating doses of CL 284,846, a non-benzodiazepine hypnotic

Effect of hypoxia on the pharmacokinetics and metabolism of zaleplon as a probe of CYP3A1/2 activity

The objective of this study was to compare the pharmacokinetics and metabolism of zaleplon (ZAL) in rats under hypoxic and normoxic condition and the effect of hypoxia on the protein expression and activities of the main metabolic enzyme CYP3A1/2.

Advances in the management of insomnia

Insomnia is highly prevalent and associated with considerable morbidity. Several very efficacious treatments, both pharmacologic and non-pharmacologic, exist for the management of insomnia. New modes of delivery and new formulations of existing sedative-hypnotic medications have been introduced. Novel agents are still being developed and tested to arrive at a hypnotic that has limited side effects while still being efficacious. Innovations with respect to behavioral interventions, which are drastically under-utilized, have focused mainly on making these interventions more widely available through dissemination efforts, briefer formats and more accessible platforms.

Current status of prediction of drug disposition and toxicity in humans using chimeric mice with humanized liver

1. Human-chimeric mice with humanized liver have been constructed by transplantation of human hepatocytes into several types of mice having genetic modifications that injure endogenous liver cells. Here, we focus on liver urokinase-type plasminogen activator-transgenic severe combined immunodeficiency (uPA/SCID) mice, which are the most widely used human-chimeric mice. Studies so far indicate that drug metabolism, drug transport, pharmacological effects and toxicological action in these mice are broadly similar to those in humans. 2. Expression of various drug-metabolizing enzymes is known to be different between humans and rodents. However, the expression pattern of cytochrome P450, aldehyde oxidase and phase II enzymes in the liver of human-chimeric mice resembles that in humans, not that in the host mice. 3. Metabolism of various drugs, including S-warfarin, zaleplon, ibuprofen, naproxen, coumarin, troglitazone and midazolam, in human-chimeric mice is mediated by human drug-metabolizing enzymes, not by host mouse enzymes, and thus resembles that in humans. 4. Pharmacological and toxicological effects of various drugs in human-chimeric mice are also similar to those in humans. 5. The current consensus is that chimeric mice with humanized liver are useful to predict drug metabolism catalyzed by cytochrome P450, aldehyde oxidase and phase II enzymes in humans in vivo and in vitro. Some remaining issues are discussed in this review.

Update on the safety considerations in the management of insomnia with hypnotics: incorporating modified-release formulations into primary care

OBJECTIVE

From a safety perspective, several issues require assessment when a decision is made to prescribe a sleep medication, including next-day residual effects, the potential for abuse, tolerance, and dependence. This article aims to provide an update of the safety profile of agents commonly used in the management of insomnia, with an emphasis on newly approved hypnotics.

DATA SOURCES

Publications relevant to the subject of this review were identified by a PubMed search (conducted without date restrictions; search terms: insomnia WITH safety OR tolerability OR side effects OR tolerance OR dependence OR abuse OR residual effects AND benzodiazepines OR non-benzodiazepines OR zolpidem OR eszopiclone OR zaleplon OR ramelteon OR melatonin OR trazodone OR antihistamines OR alcohol OR alternative therapies), and additional articles (selected by the author on the basis of his experience) were included.

STUDY SELECTION AND DATA EXTRACTION

Publications relevant to the objective of this article were obtained, and the key safety data relating to adverse events, next-day residual effects, tolerance, and withdrawal were summarized.

DATA SYNTHESIS

The non-benzodiazepines (eszopiclone, zolpidem, zolpidem extended-release, and zaleplon), which have largely replaced the benzodiazepines for insomnia treatment, have a lower risk of tolerance, dependence, abuse, and residual effects compared with benzodiazepines. The modified-release formulation of zolpidem demonstrates a comparable safety profile to that of original zolpidem but has an additional sleep maintenance benefit. Ramelteon, a novel melatonin receptor agonist, is indicated for sleep-onset difficulties and is not scheduled. Over-the-counter agents, alternative therapies, and the prescription of off-label drugs, such as trazodone, have a lack of controlled clinical efficacy and safety studies in the treatment of insomnia and as a result should be used with caution.

CONCLUSIONS

Overall, published studies report that the safety of insomnia treatments has improved considerably over the past 10 years with the introduction of agents that provide improved safety, particularly with regard to next-day residual effects and abuse liability.

Pharmacokinetic profile of SKP-1041, a modified release formulation of zaleplon

OBJECTIVES

Two investigations aimed to define the pharmacokinetic profile of a modified-release preparation of zaleplon (SKP-1041).

METHODS

Protocol SOM001 was a 5-way crossover, double-blind, randomized trial comparing three novel modified-release formulations of zaleplon 15 mg (SKP-1041A, SKP-1041B, SKP-1041C) to placebo and immediate-release zaleplon 10 mg. Protocol SOM002 was a randomized, crossover, open-label trial to compare the pharmacokinetics of SKP-1041B after day and night administration. In SOM001, study drug was administered at 9:00 a.m. (fasted); blood samples were obtained beginning 1 h predose through 12 h postdose. In study SOM002, study drug was administered at 9:00 a.m. or 10:30 p.m.; blood samples were obtained beginning 1 h predose through 12 h postdose. Subjects were 19 (SOM001) and 23 (SOM002) healthy adults between ages 20-46.

RESULTS

Dose-normalized total AUCs for modified-release preparations A, B, C and immediate-release zaleplon were not significantly different; peak plasma concentrations were similar for A and B, and both were significantly higher than C. Time to peak plasma concentration for A, B, and C were 4-5 h compared to 1.5 h for immediate-release zaleplon; mean terminal phase half-life was in the range 1-2 h for A, B and immediate-release zaleplon. No significant differences were noted between day and night administration in the SOM002 study.

CONCLUSIONS

Zaleplon, 15 mg, in a novel, modified-release formulation (SKP-1041) had a time to peak plasma concentrations at 4-5 h postdose compared to 1.5 h for immediate-release zaleplon, 10 mg. The pharmacokinetic profile suggests this formulation may be useful for treating middle-of-the-night awakening.

British Association for Psychopharmacology consensus statement on evidence-based treatment of insomnia, parasomnias and circadian rhythm disorders

Sleep disorders are common in the general population and even more so in clinical practice, yet are relatively poorly understood by doctors and other health care practitioners. These British Association for Psychopharmacology guidelines are designed to address this problem by providing an accessible up-to-date and evidence-based outline of the major issues, especially those relating to reliable diagnosis and appropriate treatment. A consensus meeting was held in London in May 2009. Those invited to attend included BAP members, representative clinicians with a strong interest in sleep disorders and recognized experts and advocates in the field, including a representative from mainland Europe and the USA. Presenters were asked to provide a review of the literature and identification of the standard of evidence in their area, with an emphasis on meta-analyses, systematic reviews and randomized controlled trials where available, plus updates on current clinical practice. Each presentation was followed by discussion, aimed to reach consensus where the evidence and/or clinical experience was considered adequate or otherwise to flag the area as a direction for future research. A draft of the proceedings was then circulated to all participants for comment. Key subsequent publications were added by the writer and speakers at draft stage. All comments were incorporated as far as possible in the final document, which represents the views of all participants although the authors take final responsibility for the document.

The effect of sleep medications on cognitive recovery from traumatic brain injury

OBJECTIVE

To summarize the literature on the available pharmacotherapy for insomnia and the adverse cognitive effects of those options in persons with traumatic brain injury (TBI).

DESIGN

Ovid/MEDLINE databases were searched by using the following key words: "brain injury," "sleep initiation and maintenance disorders," "hypnotics and sedatives," "benzodiazepines," "trazodone," and "neuronal plasticity."

RESULTS

The reviewed literature consistently reported that benzodiazepines and atypical gamma-aminobutyric acid (GABA) agonists result in cognitive impairment when plasma levels are at their peak. Evidence of residual effects on cognition was reported for benzodiazepines but was seen less often in atypical GABA agonists. However, evidence has also been presented that GABA agonists have adverse effects on neuroplasticity, raising concerns about their use in patients recovering from TBI.

CONCLUSIONS

Use of benzodiazepines in TBI has been discouraged and some authors also advocate caution in prescribing atypical GABA agonists. Alternate treatments including trazodone and a newer class of agents, melatonin agonists, are highlighted, along with the limited data available addressing the use of these medications in TBI. Finally, suggestions are offered for further research, especially on topic related to neural plasticity and functional recovery.

Clinical evaluation of zaleplon in the treatment of insomnia

Zaleplon is a pyrazolopyrimidine hypnotic used for the treatment of insomnia. Zaleplon binds preferentially at the α1β2γ2 subunit of gamma aminobutyric acid type A (GABAA) receptors in the central nervous system, and has a half-life of about one hour. Efficacy studies show that zaleplon is a suitable hypnotic for sleep initiation purposes. However, because of its short half-life, zaleplon is less effective in sleep maintenance when compared with other hypnotics. Nevertheless, zaleplon does increase total sleep time. No rebound effects are observed after treatment discontinuation. The use of zaleplon is relatively safe. Adverse effects are mild and of short duration. No important interactions have been reported, and there is no evidence of abuse potential. Relative to benzodiazepine hypnotics, the biggest advantage of zaleplon is that current evidence suggests it does not produce residual next-day effects. As early as four hours after intake of zaleplon, no effects on cognitive, memory, psychomotor performance, and the ability to drive a car have been reported. Future studies should confirm these findings, and comparisons with new nonbenzodiazepine hypnotics should determine the importance of zaleplon in the future treatment of insomnia.

Application of spectrophotometric, densitometric, and HPLC techniques as stability indicating methods for determination of Zaleplon in pharmaceutical preparations

Spectrophotometric, spectrodensitometric and HPLC are stability indicating methods described for determination of Zaleplon in pure and dosage forms. As Zaleplon is easily degradable, the proposed techniques in this manuscript are adopted for its determination in presence of its alkaline degradation product, namely N-[4-(3-cyano-pyrazolo[1,5a]pyridin-7-yl)-phenyl]-N-ethyl-acetamide. These approaches are successfully applied to quantify Zaleplon using the information included in the absorption spectra of appropriate solutions. The second derivative (D(2)) spectrophotometric method, allows determination of Zaleplon without interference of its degradate at 235.2 nm using 0.01N HCl as a solvent with obedience to Beer's law over a concentration range of 1-10 microg ml(-1) with mean percentage recovery 100.24+/-0.86%. The first derivative of the ratio spectra ((1)DD) based on the simultaneous use of ((1)DD) and measurement at 241.8 nm using the same solvent and over the same concentration range as (D(2)) spectrophotometric method, with mean percentage recovery 99.9+/-1.07%. The spectrodensitometric analysis allows the separation and quantitation of Zaleplon from its degradate on silica gel plates using chloroform:acetone:ammonia solution (9:1:0.2 by volume) as a mobile phase. This method depends on quantitave densitometric evaluation of thin layer chromatogram of Zaleplon at 338 nm over a concentration range of 0.2-1 microg band(-1), with mean percentage recovery 99.73+/-1.35. Also a reversed-phase liquid chromatographic method using 5-C8 (22 cm x 4.6 mm i.d. 5 microm particle size) column was described and validated for quantitation of Zaleplon using acetonitrile:deionised water (35:65, v/v) as a mobile phase using Paracetamol as internal standard and a flow rate of 1.5 ml min(-1) with UV detection of the effluent at 232 nm at ambient temperature over a concentration range of 2-20 microg ml(-1) with mean percentage recovery 100.19+/-1.15%. The insignificance difference of the proposed methods results with those of the reference one proved their accuracy and precision.

Therapeutic Options for Sleep-Maintenance and Sleep-Onset Insomnia

Insomnia, defined as difficulty falling asleep, staying asleep, and/or experiencing restorative sleep with associated impairment or significant distress, is a common condition resulting in significant clinical and economic consequences. Many options are available to treat insomnia, to assist with either falling asleep (sleep onset) or maintaining sleep. We searched MEDLINE for articles published between January 1996 and January 2006, evaluated abstracts from recent professional meetings, and contacted the manufacturer of the most recent addition to the pharmacologic armamentarium for insomnia treatment (ramelteon) to gather information. Nonpharmacologic options include stimulus control, sleep hygiene education, sleep restriction, paradoxical intention, relaxation therapy, biofeedback, and cognitive behavioral therapy. Prescription and over-the-counter drug therapies include benzodiazepine and nonbenzodiazepine sedative-hypnotic agents; ramelteon, a melatonin receptor agonist; trazodone; and sedating antihistamines. Herbal and alternative preparations include melatonin and valerian. Before recommending any treatment, clinicians should consider patient-specific criteria such as age, medical history, and other drug use, as well as the underlying cause of the sleep disturbance. All pharmacotherapy should be used with appropriate caution, at minimum effective doses, and for minimum duration of time.

Effect of sleep apnea on cognition and mood

Obstructive sleep apnea syndrome (OSAS) is a common disorder in adults and children, which is characterized by repetitive transient reversible upper airway obstructions during sleep. Due to disrupted sleep architecture and intermittent hypoxemia, OSAS leads to impaired daytime functioning in various neuropsychological and affective domains. The most common abnormalities are executive dysfunction, impaired vigilance, depression, and possibly anxiety and, in children, hyperactivity. Optimal treatment of OSAS with continuous positive airway pressure may reverse the cognitive and affective dysfunction, however, in some patients a residual impairment persists. This persistent deficit, despite effective treatment, raises the possibility of a remaining subtle structural brain damage; such damage has been demonstrated through the use of sensitive functional and other neuroimaging techniques. Prefrontal cortical damage may underlie the cognitive dysfunction in OSAS. Early recognition and treatment may prevent this untoward effect of OSAS.

The condition of insomnia: etiopathogenetic considerations and their impact on treatment practices

Insomnia is conceived as the subjective complaint of reduced sleep quantity and/or quality, even in the absence of objective verification of sleep loss; it is the outcome of the interplay of many environmental, biological, and psychological factors, which can be distinguished into predisposing, precipitating and perpetuating. Predisposing and precipitating factors include various demographic characteristics and the occurrence of psychiatric or somatic illnesses as well as other stressful life events. The perpetuating factors, responsible for the development of chronicity of the complaint of insomnia, mainly involve a 24-hour state of hyperarousal and a vicious cycle of sleeplessness causing fear of sleeplessness which in turn leads to further hyperarousal and more sleeplessness. Particular psychological characteristics, including excessive use of denial and repression as well as a strong propensity for internalisation of emotions, are also among the main factors contributing to the psychophysiological activation and state of hyper-arousability commonly encountered among insomniac patients. The treatment should not only focus on ameliorating sleeplessness, it should also address all those factors that cause and maintain insomnia. An integrative management of insomnia includes education on sleep hygiene measures, behavioural, cognitive and psychodynamic psychotherapies, and the utilization of sleep-promoting drugs. Among the latter, only for the use of benzodiazepine or benzodiazepine-like hypnotics exists sufficient evidence for efficacy as well as adequate information on their side-effect profiles. Thus, these compounds are considered as the drugs of choice for the treatment of insomnia. It is recommended that the use of hypnotic drugs is restricted to the initial period of treatment; they should be rationally utilized within the context of a broad therapeutic program, which is based on a sound doctor-patient relationship and includes sleep hygiene education and the application of certain psychotherapeutic techniques in an individualized manner.

Benefit-risk assessment of zaleplon in the treatment of insomnia

Insomnia is a heterogeneous, highly prevalent condition that is associated with a high level of psychiatric, physical, social and economic morbidity. The treatment of insomnia involves pharmacological and non-pharmacological interventions. The mainstay of pharmacological treatment of insomnia has been the benzodiazepines, the introduction of which represented a significant improvement over the barbiturates and chloral hydrate. Although benzodiazepines have been shown to be efficacious in treating insomnia, they have also been associated with a number of adverse effects including tolerance, dependence, withdrawal and abuse potential, impairment in daytime cognitive and psychomotor performance (including an increased risk of accidents and falls), adverse effects on respiration and the disruption of normal sleep architecture with reduction in both slow wave sleep and rapid eye movement. In the last decade, the treatment of insomnia has been supplemented by the introduction of a number of non-benzodiazepine hypnotics including zolpidem, zopiclone and, most recently, zaleplon. Zaleplon possesses a unique pharmacological profile, with an ultra-short half-life of about 1 hour, and selective binding to the BZ1(omega1) receptor subtypes of the GABA(A) receptor. This unique pharmacological profile predicts a number of pharmacodynamic properties that account for a unique benefit-risk profile. Consistent with these predictions, zaleplon has been shown in a number of studies to be efficacious in promoting sleep initiation, but less so in promoting sleep maintenance. The adverse effects associated with zaleplon have been shown to be more rapidly resolved and/or lesser in magnitude than those associated with benzodiazepines (including triazolam) and the longer acting non-benzodiazepine hypnotics (zolpidem and zopiclone). This improved risk profile includes: the effects of zaleplon on psychomotor and cognitive performance; tolerance, withdrawal and rebound; respiratory depression; sleep architecture; and other treatment-emergent adverse effects. The unique benefit-risk profile of this agent may be particularly suitable for certain patients with insomnia and provides yet another option in the management of this impairing condition.

Electroencephalographic properties of zaleplon, a non-benzodiazepine sedative/hypnotic, in rats

The encephalographic (EEG) properties of zaleplon were investigated in comparison with those of other sedative hypnotics in conscious rats with chronically implanted electrodes. The oral administration of zaleplon (0.25-1.0 mg/kg), triazolam (0.0625-0.25 mg/kg), zopiclone (1.0-4.0 mg/kg), brotizolam (0.0625-0.25 mg/kg), and nitrazepam (0.125-0.5 mg/kg) lengthened the total sleep in a dose-dependent manner. On distribution of sleep-wakefulness stages, zaleplon, in particular, increased the slow wave deep sleep (SWDS), whereas triazolam, brotizolam, and nitrazepam increased the slow wave light sleep (SWLS) in a dose-dependent manner. Zopiclone significantly increased the SWDS at a dose of 2 mg/kg and both the SWLS and the SWDS at a dose of 4 mg/kg. All tested hypnotics caused no influence on fast wave sleep (FWS) at doses tested. The appearance of the sleep-inducing activity of zaleplon was more rapid than those of any compounds tested, and zaleplon significantly increased the relative EEG power density in the delta frequency band over that of triazolam at 20 and 30 min after the administration in the spectral analysis. Therefore, the present findings suggest that the non-benzodiazepine zaleplon can be expected to exhibit high practical potential as a hypnotic and is characterized by an increase in SWDS with rapid onset of hypnotic action.

Comparative pharmacokinetics and pharmacodynamics of short-acting hypnosedatives: zaleplon, zolpidem and zopiclone

Benzodiazepines have historically been the mainstay of treatment for sleeping disorders, yet they have many shortcomings. A new group of sedative hypnotic agents has been developed for this purpose. Similar to the benzodiazepines, zaleplon, zolpidem and zopiclone have activity at the GABA receptor complex, yet they appear to have more selectivity for certain subunits of the GABA receptor. This produces a clinical profile that is more efficacious with fewer side effects. Zaleplon, zolpidem and zopiclone are structurally distinct. Due to variation in binding to the GABA receptor subunits, these three compounds show subtle differences in their effect on sleep stages, and as antiepileptics, anxiolytics and amnestics. The duration of action of zaleplon, zolpidem and zopiclone can be related to their individual pharmacokinetic profile, which subsequently determines the time course of drug effect. Each of these compounds has a unique pharmacokinetic profile with different bioavailability, volume of distribution and elimination half-lives. Zaleplon has a rapid elimination so there are fewer residual side effects after taking a single dose at bedtime. By comparison, zolpidem and zopiclone have a more delayed elimination so there may be a prolonged drug effect. This can result in residual sedation and side effects but may be useful for sustained treatment of insomnia with less waking during the night. There are also differences in potency based on plasma concentrations suggesting that there are differences in binding to the GABA receptor complex. Although zaleplon has a much lower bioavailability (30%), the treatment dose is similar to zolpidem and zopiclone (bioavilaibility of 70%) because of the increased potency of zaleplon. The pharmacokinetics and pharmacodynamics of zaleplon, zolpidem and zopiclone are significantly different from benzodiazepines. The new drugs are sufficiently unique from each other to allow customisation of treatment for various types of insomnia. While zaleplon may be best indicated for the delayed onset of sleep, zolpidem and zopiclone may be better indicated for maintaining a complete night's sleep. Only the patient's symptoms and response to treatment will dictate the best course of treatment.

Effect of zaleplon, a non-benzodiazepine hypnotic, on melatonin secretion in rabbits

Melatonin, a major hormone secreted by the pineal gland, is known to play an important role in regulation of the circadian rhythm. (N-[3-(3-cyanopyrazolo[1,5-a]pyrimidin-7-yl)phenyl]-N-ethylacetamide (zaleplon) is a non-benzodiazepine hypnotic that acts via the benzodiazepine site of the GABA(A) receptor. In the present study, we investigated the effect of zaleplon on melatonin secretion in rabbits using RIA and compared the effect to triazolam and zopiclone. Zaleplon increased a dose-dependent concentration of melatonin in rabbit plasma collected at 30 min after intravenous administration at doses of 1 and 2 mg/kg. The zaleplon-induced increase in plasma melatonin level was not blocked by flumazenil, a benzodiazepine-receptor antagonist. In contrast, triazolam and zopiclone failed to affect the plasma melatonin level. We also investigated the effect of zaleplon on intracellular cAMP in rat pinealocytes. Consequently, zaleplon had no effect on the intracellular cAMP levels in rat pinealocytes. These results of the present studies suggest that zaleplon may promote melatonin secretion and the elevation of plasma levels of melatonin may suggest an influence of zaleplon on chronobiology.

Molecular mechanisms of tolerance to and withdrawal of GABA(A) receptor modulators

Here, we summarize recent data pertaining to the effects of GABA(A) receptor modulators on the receptor gene expression in order to elucidate the molecular mechanisms behind tolerance and dependence induced by these drugs. Drug selectivity and intrinsic activity seems to be important to evidence at the molecular level the GABA(A) receptor tolerance. On the contrary, we suggested that all drug tested are equally potentially prone to induce dependence. Our results demonstrate that long-lasting exposure of GABA(A) receptors to endogenous steroids, benzodiazepines and ethanol, as well as their withdrawal, induce marked effects on receptor structure and function. These results suggest the possible synergic action between endogenous steroids and these drugs in modulating the functional activity of specific neuronal populations. We report here that endogenous steroids may play a crucial role in the action of ethanol on dopaminergic neurons.

Separation and identification of zaleplon metabolites in human urine using capillary electrophoresis with laser-induced fluorescence detection and liquid chromatography–mass spectrometry

A capillary electrophoresis (CE) method using laser-induced fluorescence (LIF) detection for the determination of the hypnotic drug zaleplon and its metabolites in human urine could be developed using carboxymethyl-beta-cyclodextrin as a charged carrier. By the help of a complementary HPLC method coupled to mass spectrometry, three metabolites present in human urine could be identified as 5-oxozaleplon, 5-oxo-N-deethylzaleplon and 5-oxozaleplon glucuronide. N-Deethylzaleplon, a previously described zaleplon metabolite, as well as zaleplon itself could not be detected in human urine by the CE-LIF assay. The results were confirmed by spiking with reference compounds of the phase I metabolites. The metabolites differed very much concerning their fluorescence intensities, thus the 5-oxo metabolites present as lactam tautomer fluoresced tenfold lower than the unchanged drug zaleplon and its N-deethylated metabolite. The glucuronide of the 5-oxozaleplon, however, showed high fluorescence due to its lactim structure. Limits of quantification yielded by the CE-LIF assay including a ten-fold preconcentration step by solid-phase extraction were 10 ng/ml for zaleplon and N-deethylzaleplon and 100 ng/ml for 5-oxozaleplon and 5-oxo-N-deethylzaleplon.

Problems with sleep: what should the doctor do?

Complaints of poor sleep are frequent. The physician's assessment should seek to diagnose the social, medical, and psychiatric etiologies of insomnia and to treat the identified causative conditions. Management must match the specific pathology and type of sleep problem.

New drugs for insomnia: comparative tolerability of zopiclone, zolpidem and zaleplon

Insomnia affects 30-35% of people living in developed countries. The impact of insomnia on daytime functioning and its relationship with medical and psychiatric illnesses necessitate early treatment to prevent insomnia becoming persistent and to avoid the development of complications. However, pharmacological strategies must achieve a balance between sedative and adverse effects. In the last 30 years, benzodiazepines have been the preferred drugs for the treatment of insomnia. Benzodiazepines act nonselectively at two central receptor sites, named omega(1) and omega(2), which are located in different areas of the CNS. The sedative action of benzodiazepines is related to omega(1) receptors, whereas omega(2) receptors are responsible for their effects on memory and cognitive functioning. According to their pharmacokinetic profile, benzodiazepines can be classified into three groups: short half-life (<3 hours), medium half-life (8-24 hours) and long half-life (>24 hours). The newer non-benzodiazepine agents zopiclone, zolpidem and zaleplon have a hypnosedative action comparable with that of benzodiazepines, but they display specific pharmacokinetic and pharmacodynamic properties. These three 'Z' agents all share a short plasma half-life and limited duration of action. In addition, these agents are selective compounds that interact preferentially with omega(1) receptors (sedative effect), whereas benzodiazepines also interact with omega(2) receptors (adverse effects on cognitive performance and memory). Zaleplon is characterised by an ultrashort half-life (approximately 1 hour). Zolpidem and zopiclone have longer half-lives (approximately 2.4 and 5 hours, respectively). These properties, together with the low risk of residual effect, may explain the limited negative influences of these agents on daytime performance. Psychomotor tasks and memory capacities appear to be better preserved by non-benzodiazepine agents than by benzodiazepines. When present, cognitive deficits almost exclusively coincide with the peak plasma concentration. In particular, impairment can emerge in the first hours after drug administration, whereas psychomotor and memory tests carried out 7-8 hours later (i.e. in the morning) generally show no relevant alterations. As with benzodiazepines, the three 'Z' non-benzodiazepine agents should be used for a limited period, even in chronic relapsing conditions. Further evaluation is needed of the safety of hypnosedative medications in the long-term management of insomnia.

Safety of zaleplon in the treatment of insomnia

OBJECTIVE

To evaluate the safety of zaleplon, a quick-acting, rapidly eliminated nonbenzodiazepine (non-BZD) hypnotic, as described in clinical investigations of adult and/or elderly subjects.

DATA SOURCES

Published and presented studies evaluating zaleplon, a novel non-BZD, were identified via MEDLINE (1995-July 2001), Current Contents (ISI database), bibliographic reviews, and consultation with sleep specialists who also identified published abstracts containing data not yet published in peer-reviewed journals.

DATA SYNTHESIS

Transient and chronic insomnia are common problems that should be clinically evaluated and appropriately treated. BZDs have been a primary pharmacotherapy for treating insomnia, despite their disadvantages. Newer hypnotics, characterized by increased receptor-binding specificity and favorable pharmacokinetics, provide potentially better alternatives to BZDs. Assessments included residual sedation, psychomotor impairment, or cognitive dysfunction during treatment, as well as the occurrence of rebound insomnia and withdrawal effects after discontinuation of therapy.

CONCLUSIONS

Zolpidem, the first non-BZD hypnotic, appears to have short- and long-term safety profiles similar to those of the BZD triazolam. Zaleplon, a newer non-BZD sleep medication, has a quick onset of action and undergoes rapid elimination, which results in a better safety profile than previously available agents. Additionally, rebound insomnia and other withdrawal effects have not been demonstrated with zaleplon, and the drug is well tolerated in both young and elderly patients. These characteristics may be clinically advantageous for patients who should not receive BZDs.

Changes in GABA(A) receptor gene expression induced by withdrawal of, but not by long-term exposure to, zaleplon or zolpidem

The effects of long-term treatment with and subsequent withdrawal of the two hypnotic drugs zaleplon and zolpidem on the abundance of gamma-aminobutyric acid type A (GABA(A)) receptor subunit mRNAs in cultured rat cerebellar granule cells were investigated. Incubation of neurons with either drug at a concentration of 10 microM for 5 days did not significantly affect the amounts of mRNAs encoding the alpha(1), alpha(4), beta(1), beta(2), beta(3), gamma(2)L, or gamma(2)S subunits. As expected, similar treatment with the nonselective benzodiazepine diazepam resulted in a decrease in the abundance of alpha(1), beta(2), gamma(2)L, and gamma(2)S subunit mRNAs as well as an increase in that of the beta(1) subunit mRNA. Withdrawal of zaleplon or zolpidem, like that of diazepam, induced a marked increase in the amount of the alpha(4) subunit mRNA. In addition, discontinuation of treatment with either hypnotic drug resulted in a decrease in the amounts of alpha(1), beta(2), gamma(2)L, and gamma(2)S subunit mRNAs as well as an increase in that of the beta(1) subunit mRNA. These effects of zaleplon and zolpidem on GABA(A) receptor gene expression are consistent with the reduced tolerance liability of these drugs, compared with that of diazepam, as well as with their ability to induce both physical dependence and withdrawal syndrome.

Noise-induced sleep maintenance insomnia: hypnotic and residual effects of zaleplon

AIMS

The primary objective of the study was to assess the residual effects of zaleplon in the morning, 4 h after a middle-of-the-night administration. The secondary objective was to investigate the effectiveness of zaleplon in promoting sleep in healthy volunteers with noise-induced sleep maintenance insomnia.

METHODS

Thirteen healthy male and female volunteers (aged 20-30 years) with normal hearing, who were sensitive to the sleep-disrupting effects of noise, participated in a double-blind, placebo- and active-drug controlled, four-period cross-over study. The subjects were permitted to sleep for 5 h (22.45-03.45 h) in a quiet environment before they were awoken. At 04.00 h they ingested 10 mg zaleplon, 20 mg zaleplon, 7.5 mg zopiclone (active control), or placebo before a second period of sleep (04.00-08.00 h), during which they were exposed to an 80 dB(A) 1 kHz pure tone pulse with an inter-tone interval of 1 s and a duration of 50 ms. The sound stimulus was stopped after 10 min of persistent sleep or after 2 h if the subject had not fallen asleep. Residual effects were assessed at 08.00 h (4 h after drug administration) using the digit symbol substitution test (DSST), choice reaction time (CRT), critical flicker fusion (CFF), and immediate and delayed free recall of a 20 word list. The data were analysed by analysis of variance. A Bonferroni adjustment was made for the three active treatments compared with placebo.

RESULTS

There were no residual effects of zaleplon (10 and 20 mg) compared with placebo. Zopiclone impaired memory by delaying the free recall of words (P = 0.001) and attenuated performance on DSST (P = 0.004) and CRT (P = 0.001), compared with placebo. Zaleplon reduced the latency to persistent sleep (10 mg, P = 0.001; 20 mg, P = 0.014) and the 20 mg dose reduced stage 1 sleep (P = 0.012) compared with placebo. Zopiclone reduced stage 1 sleep (P = 0.001), increased stage 3 sleep (P = 0.0001) and increased total sleep time (P = 0.003), compared with placebo.

CONCLUSIONS

Zaleplon (10 mg and 20 mg), administered in the middle of the night 4 h before arising, shortens sleep onset without impairing next-day performance.

Binding and neuropharmacological profile of zaleplon, a novel nonbenzodiazepine sedative/hypnotic

The binding properties of CL284,846 (zaleplon), a novel nonbenzodiazepine sedative/hypnotic, at benzodiazepine receptor subtypes were evaluated. Zaleplon was 14.3 times more potent at inhibiting [3H]flunitrazepam binding to membrane preparations of the cerebellum than to membrane preparations of the spinal cord. The gamma-aminobutyric acid (GABA) ratio of zaleplon was 2.07. Zaleplon produced significant increases in muscimol binding similar to those of diazepam, and it was antagonized by flumazenil. Furthermore, zaleplon showed little affinity for other receptors. Spectral analysis of the electroencephalogram (EEG) of rabbits showed that zaleplon and 3-methyl-6-[3-(trifluoromethyl) phenyl]-1,2,4,-triazolo [4,3-beta] pyridazine (CL218,872), an omega(1) receptor-selective compound (1 mg/kg, i.v., respectively), produced large increases in energy of the delta frequency band without affecting the energy of the alpha and beta frequency bands. In contrast, intravenous administration of triazolam and zopiclone increased the energy of the beta frequency band at doses of 0.1 and 2 mg/kg, respectively. In addition, the zaleplon-induced increase in the energy of the delta frequency band was antagonized by pretreatment with flumazenil (1 mg/kg, i.v.), which did not affect the spontaneous EEG alone. The present results clearly demonstrate that zaleplon is a selective full agonist of the omega(1) receptor subtype, and thus, zaleplon may induce responses closely resembling the physiological pattern of slow wave sleep.

Pyrazolopyrimidines

Pharmacological therapy has an important role in the management of insomnia. Although older drugs are highly effective for initiating and maintaining sleep, tolerance and withdrawal effects as well as impairment of daytime performance are commonly troublesome and limit their use. Aided by increased knowledge of gamma-aminobutyric acid (GABA) and its receptors, new hypnotic sedatives have been developed that are increasingly selective for the various subunits of the GABA receptor. This development has produced newer agents with very favourable hypnotic profiles and side-effect profiles that provide better treatment options for medical practitioners. The pyrazolopyrimidines, the latest in this area, seem to offer some advantages over other agents.

Treatment of insomnia in hospitalized patients

OBJECTIVE

To provide recommendations for the short-term management of insomnia in hospitalized patients and review patient assessment, nonpharmacologic treatment modalities, and selection of hypnotic medications.

DATA SOURCES

Review articles and primary literature representative of current knowledge regarding the treatment of insomnia were identified by MEDLINE search (1966-January 2001). Search terms included insomnia (sleep initiation and maintenance disorders), benzodiazepines, zaleplon, zolpidem, and trazodone.

DATA SYNTHESIS

Literature regarding the management of insomnia in hospitalized patients is limited; therefore, data pertinent to the treatment of ambulatory patients must be extrapolated to the inpatient setting. When evaluating insomnia in hospitalized patients, it seems reasonable to obtain a thorough history and physical examination to identify potential underlying etiologies. Treatment of these underlying etiologies should be considered. When the use of a sedative-hypnotic agent is necessary, medication and dose selection should be based on the pharmacokinetic and adverse effect profiles of each agent. Patent-specific characteristics should also be considered to provide effective treatment while minimizing adverse effects.

CONCLUSIONS

Nonpharmacologic approaches to the treatment of insomnia should be considered for hospitalized patients. When sedative-hypnotic medications must be administered, the pharmacokinetic profile of intermediate-acting benzodiazepines (e.g., lorazepam, temazepam) makes them good first-line agents. Zaleplon and zolpidem are also attractive hypnotic agents; however, they are typically reserved for second-line therapy due to cost. Trazodone may be an alternative for patients unable to take benzodiazepines.

Pharmacodynamic profile of Zaleplon, a new non-benzodiazepine hypnotic agent

The challenge in developing hypnotic agents for the treatment of insomnia is to balance the sedative effect needed at bedtime with the residual sedation on awakening. Zaleplon is a novel pyrazolopyrimidine hypnotic agent that acts as a selective agonist to the brain omega(1) receptor situated on the alpha(1) subunit of the GABA(A) receptor complex. Zaleplon was proven to be an effective hypnotic drug as it consistently and significantly reduced latency to persistent sleep in insomniac patients for doses of 10 mg and above in polysomnography studies. The pharmacodynamic profile of zaleplon on psychomotor performance, actual driving and cognitive function, including memory, was assessed in several randomized, double-blind, placebo-controlled studies in healthy young subjects as well as insomniac patients by using various positive controls (zolpidem, zopiclone, triazolam and flurazepam). The recommended hypnotic dose of zaleplon in young adults (10 mg) produced minimal or no impairment of psychomotor and memory performance even when administered during the night as little as 1 h before waking. No impairment of actual driving was observed when zaleplon 10 mg was administered either at bedtime or in the middle of the night as little as 4 h before waking. Zaleplon 20 mg, twice the recommended dose, generally produced significant impairment of performance and cognitive functions when these functions were measured at the time of peak plasma concentration, i.e. 1 h after dose administration, and no impairment of driving abilities was observed 4 h after a middle-of-the-night administration. In contrast, consistent detrimental residual effects on various aspects of psychomotor and cognitive functions were observed with the therapeutic doses of the various commonly prescribed hypnotic agents used as comparators, e.g. zolpidem 10 mg up to 5 h after dose administration, zopiclone 7.5 mg up to 10 h after, flurazepam 30 mg up to 14 h after and triazolam 0.25 mg up to 6 h after. Also, zolpidem 10 mg and zopiclone 7.5 mg were also shown to significantly impair driving ability the next morning when this was measured 4 h and up to 10 h after dose administration, respectively. The present review shows that zaleplon 10 mg has little or no residual effect when administered in the middle of the night, as late as 1 h before waking, and is devoid of impairment of driving abilities as assessed by actual driving 4 h after dose administration. The lack of clinically significant or minimally statistically significant residual effects of zaleplon even at its peak concentration may be explained by its unique pharmacokinetic (rapid elimination half-life) and pharmacodynamic (low affinity, and specific binding profile to various subunits of the GABA(A)receptor) profiles. These properties allow zaleplon to be used for treatment of symptoms only when they occur, either at bedtime or later in the night, without incurring significant risk of developing next-day impairment of psychomotor and cognitive functioning. Copyright 2001 John Wiley & Sons, Ltd.

The Importance of Residual Effects When Choosing a Hypnotic: The Unique Profile of Zaleplon

BACKGROUND: Insomnia is a prevalent medical disorder that has significant effects on occupational performance, health, and quality of life. Insomnia places an enormous burden on society through increased visits to physicians, loss of productivity in the workplace, and an increased rate of accidents. An estimated sum of $100 million is spent each year on direct treatment of unresolved insomnia. Physicians need to initiate early effective treatment to prevent development of chronic insomnia and its associated morbidity. Institution of good sleep hygiene practices may be useful in some patients but may not be adequate for resolution of all sleep problems. Behavioral treatments, while effective and durable, are time consuming and not widely utilized in clinical practice. Pharmacotherapy includes benzodiazepine hypnotics, but concerns regarding adverse effects (e.g., residual sedation) prompted the search for safer options. DATA SOURCES: Published and presented studies containing clinical data on zaleplon, a new nonbenzodiazepine sleep medication, were identified via MEDLINE, Current Contents (ISI database), bibliographic reviews, and consultation with sleep specialists. RESULTS: Zaleplon effectively shortens sleep onset time and improves the quality of sleep in patients with insomnia. Whether administered at bedtime or later at night, zaleplon is devoid of residual sedative effects that impair next-day functioning. Follow-up studies evaluating the long-term efficacy and safety of zaleplon showed that decreased time to sleep onset was maintained during therapy lasting up to 52 weeks, without a withdrawal syndrome after discontinuation. CONCLUSION: Insomnia is recurrent and unpredictable in nature. Despite the long-term morbidity of this sleep disorder, research evidence and practice guidelines have not explored long-term use of hypnotics. Many patients could benefit from long-term drug therapy with a sleep medication that is devoid of residual effects and can be taken at bedtime or later as symptoms occur, rather than nightly in anticipation of a sleep problem.

Zaleplon and triazolam physical dependence assessed across increasing doses under a once-daily dosing regimen in baboons

The ability of the GABA(A)-receptor-subtype-selective hypnotic zaleplon to produce physical dependence was compared to the nonselective benzodiazepine triazolam. Progressively increasing doses of zaleplon and triazolam were given to baboons by intragastric infusion once each day, with doses increasing every 17 days. Next, the highest dose was given for 10-34 additional days by continuous infusion. Both drugs produced increases in food-maintained lever pressing, ataxia, and time to complete a fine motor task. Plasma levels increased dose-dependently; drug was detectable 24 h after higher doses. Flumazenil produced a mild or intermediate precipitated-withdrawal syndrome on day 14 of all dosing conditions. When drug delivery ended after 85-100 days, a benzodiazepine-type withdrawal syndrome occurred. Physical dependence potential of zaleplon and triazolam appear similar.

Zaleplon and triazolam: drug discrimination, plasma levels, and self-administration in baboons

Zaleplon is a chemically novel hypnotic that preferentially binds alpha(1)-subunit containing subtypes of the alphabetagamma configuration of the gamma-aminobutyric acid (GABA)(A) receptor. Zaleplon and the non-subtype-selective hypnotic triazolam occasioned 100% drug-appropriate responding in baboons trained to discriminate lorazepam or pentobarbital from vehicle. Flumazenil shifted the zaleplon generalization gradient at least five-fold to the right. A plasma elimination half-life of 6-8 h for oral 10 mg/kg zaleplon and 0.32 mg/kg triazolam was paralleled by discriminative control for 7 h. Zaleplon maintained self-injection greater than vehicle, as did comparison doses of the similarly selective hypnotic zolpidem and triazolam. Concurrent food-maintained responding increased during self-injection of all three drugs. Preferential binding at this alpha(1)-containing GABA(A) subtype did not diminish the benzodiazepine (Bzs)-like behavioral effects of zaleplon.

Pharmacokinetics, pharmacodynamics, and relative pharmacokinetic/pharmacodynamic profiles of zaleplon and zolpidem

OBJECTIVE

This study compared the pharmacokinetics, pharmacodynamics, and pharmacokinetic/pharmacodynamic (PK/PD) profile of zaleplon, a new pyrazolopyrimidine hypnotic, with those of zolpidem and placebo.

METHODS

This was a double-blind, 5-period crossover study in which healthy volunteers with no history of sleeping disorder were randomized to 10- or 20-mg oral doses of zaleplon, 10- or 20-mg oral doses of zolpidem, or placebo. The pharmacokinetic characteristics of the active drugs were estimated using a noncompartmental method and NONMEM. Pharmacodynamic characteristics were determined using psychophysical tests, including measures of sedation, mood, mental and motor speed, and recent and remote recall. Results of these tests were used to compare the drugs' relative PK/PD profiles.

RESULTS

Ten healthy male and female volunteers, aged 23 to 31 years, took part in the study. The apparent elimination half-life of zaleplon (60.1+/-8.9 min) was significantly shorter than that of zolpidem (124.5+/-37.9 min) (P < 0.001). Zaleplon produced less sedation than zolpidem at the 2 doses studied (P < 0.001). The sedation scores of the zaleplon groups returned to baseline in less time than those of the zolpidem groups (4 vs 8 hours; P < 0.05). Zaleplon had no effect on recent or remote recall, whereas zolpidem had a significant effect on both measures (P < 0.05).

CONCLUSIONS

In this study in 10 young, healthy volunteers, zaleplon was eliminated more rapidly, produced no memory loss, and caused less sedation than zolpidem at the same doses.

Dose-response effects of zaleplon as compared with triazolam (0.25 mg) and placebo in chronic primary insomnia

The effects of two nights of treatment with the short-acting benzodiazepine receptor agonist zaleplon, triazolam, or placebo was assessed in chronic primary insomniacs using two concurrent, multi-center, randomized, double-blind, Latin Square crossover studies. Study 1 (n = 47) compared zaleplon (10 and 40 mg) to triazolam (0.25 mg) and placebo. Study 2 (n = 36) compared zaleplon (20 and 60 mg) to triazolam (0.25 mg) and placebo. For each study, polysomnographically recorded sleep parameters and patient reports of sleep quality were collected during baseline and two consecutive nights during the four treatment phases in each study. All doses of zaleplon produced significant decreases in latency to persistent sleep. Although no minimally effective dose could be determined, dose-response effects were apparent. Triazolam 0.25 mg produced a decrease in latency to persistent sleep that was comparable to that of zaleplon 10 mg. Only the triazolam dose and the 60 mg dose of zaleplon produced significant increases in total sleep time over placebo. Zaleplon 40 and 60 mg and triazolam produced decreases in the percentage of REM sleep compared to placebo. Patient reports of efficacy were consistent with objective findings. In addition, all doses of zaleplon tended to increase while triazolam decreased the percentage of stage 3/4 sleep. There was no evidence of residual daytime impairment for any of the zaleplon doses, however, triazolam administration produced significant impairment in performance on a digit copying test. A higher number of adverse events were seen with the 40 and 60 mg doses of zaleplon compared to triazolam (0.25) and placebo. At higher doses, zaleplon is more effective than triazolam at reducing latency to persistent sleep in chronic insomnia and is not associated with the decrease in slow-wave sleep or residual impairment observed with triazolam. However, increases in total sleep time were apparent only at doses which produced concomitant increases in the number of adverse events. In contrast, triazolam (0.25 mg) produced increases in total sleep time (;25 min) and decreases in latency to persistent sleep at a dose of 0.25 mg. Copyright 2000 John Wiley & Sons, Ltd.

Zaleplon: a pyrazolopyrimidine sedative-hypnotic agent for the treatment of insomnia

BACKGROUND

Insomnia is the subjective complaint of poor sleep or an inadequate amount of sleep that adversely affects daily functioning. For the past 4 decades, treatment of insomnia has shifted away from the use of barbiturates toward the use of hypnotic agents of the benzodiazepine class. However, problems associated with the latter (eg, next-day sedation, rebound insomnia, dependence, and tolerance) have prompted development of other agents.

OBJECTIVE

This review describes the recently approved nonbenzodiazepine agent, zaleplon.

METHODS

Studies of zaleplon were identified through a search of English-language articles listed in MEDLINE and International Pharmaceutical Abstracts, with no limitation on year. These were supplemented by educational materials from conferences.

RESULTS

The efficacy and tolerability of zaleplon have been documented in the literature. Zaleplon has been shown to improve sleep variables in comparison with placebo. Like most hypnotic agents, zaleplon can be used for problems of sleep initiation at the beginning of the night, but its short duration of clinical effect may also allow patients to take it later in the night without residual effects the next morning. Zaleplon can be taken < or = 2 hours before awakening without "hangover" effects. It is generally well tolerated, with headache being the most commonly reported adverse event in clinical trials (15%-18%). Compared with flurazepam, a long-acting benzodiazepine sedative-hypnotic agent, zaleplon causes significantly less psychomotor and cognitive impairment (P < 0.001). Zaleplon has not been studied in pregnant women or children. The dose of zaleplon should be individualized; the recommended daily dose for most adults is 10 mg.

CONCLUSIONS

Insomnia has a substantial impact on daily functioning. If pharmacologic treatment is indicated for insomnia, the choice of an agent should be guided by individual patient characteristics.

Zaleplon shortens subjective sleep latency and improves subjective sleep quality in elderly patients with insomnia. The Zaleplon Clinical Investigator Study Group

Insomnia is a frequent complaint in the elderly population. Hypnotic agents, including benzodiazepines, with longer pharmacological half-lives have been associated with side effects, including residual sedation, memory impairment, and discontinuation effects. Zaleplon is a short-acting (elimination half-life of 1 hour), non-benzodiazepine hypnotic that acts on the benzodiazepine type 1 site of the gamma-aminobutyric acid type A (GABA(A)) receptor complex. The pharmacology and pharmacokinetics of Zaleplon suggest a safety profile that is improved over other hypnotics. The objective of this placebo-controlled study was to evaluate the efficacy and safety of Zaleplon (5 and 10 mg) in elderly (> or =65 years) outpatients with primary insomnia. This was a multicenter, double-blind, randomised, placebo-controlled 2-week outpatient study. Postsleep questionnaires were used to record subjective sleep variables: sleep latency, sleep duration, number of awakenings, and sleep quality. Zaleplon significantly reduced subjective sleep latency during both weeks of the study with both 5- and 10-mg doses. Subjective sleep quality was improved for significantly more patients treated with zaleplon 10 mg than those treated with placebo during both weeks of treatment. There was a weak indication of rebound insomnia after discontinuation of treatment with the 10-mg dose, but no significant difference in common treatment-emergent adverse events across treatment groups. Zaleplon is an effective and safe hypnotic for the treatment of insomnia in the elderly.

Zaleplon: a review of its use in the treatment of insomnia

Zaleplon is a pyrazolopyrimidine hypnotic agent which is indicated for the short term (2 to 4 weeks) management of insomnia. Zaleplon 5 and 10 mg at bedtime (usual recommended doses) significantly reduced sleep latency compared with placebo in clinical trials in nonelderly and elderly patients with insomnia. In general, sleep maintenance (sleep duration and number of awakenings) and sleep quality were not significantly different from placebo with zaleplon 5 and 10 mg/night. Zaleplon 20 mg/night significantly improved sleep latency and duration in nonelderly patients, but effects on number of awakenings were inconsistent and sleep quality generally did not improve. The relative hypnotic efficacy of zaleplon compared with that of triazolam and zolpidem is not yet clearly established. Tolerance to the hypnotic effects of zaleplon generally did not occur during 5 weeks' treatment, or during long term treatment (6 or 12 months) according to a small number of studies presented as abstracts. Zaleplon was well tolerated in clinical trials. The most common event was headache but the incidence was similar to that observed with placebo. Zaleplon 5 and 10 mg did not impair psychomotor function or memory even immediately after the dose in studies in volunteers or patients with insomnia. Zaleplon 20 mg, however, impaired psychomotor function and memory immediately after the dose but next-day effects were not observed. The psychomotor profile of zaleplon appears to be better than that of comparator agents. Rebound insomnia was not observed after sudden discontinuation of up to 12 months' treatment with zaleplon 5 and 10 mg/night and up to 4 weeks' treatment with zaleplon 20 mg/night. In addition, the potential for withdrawal syndrome with zaleplon appears to be low according to limited data. In conclusion, zaleplon 5, 10 and 20 mg administered at bedtime, or later if patients have difficulty sleeping, is an effective and well tolerated hypnotic agent. There was no evidence of next-day residual effects with the 5 and 10 mg dosages, and the incidence of withdrawal effects with zaleplon 5, 10 and 20 mg did not differ significantly to that observed with placebo. In addition, tolerance to the effects of zaleplon is unlikely to develop when administered for the recommended treatment period. The comparative efficacy and tolerability of zaleplon with other short acting nonbenzodiazepine hypnotics is difficult to establish. However, on the basis of current efficacy evidence and the lower incidence of residual effects with zaleplon 5 and 10 mg relative to comparator agents, this drug represents a useful option in the management of patients with insomnia who have difficulties initiating sleep.

Comparison of the effects of zaleplon, zolpidem, and triazolam on memory, learning, and psychomotor performance

Twenty-four healthy male and female subjects, who participated in this randomized, double-blind, crossover study, received single nighttime doses of zaleplon 10 mg (therapeutic dose), zaleplon 20 mg, zolpidem 10 mg (therapeutic dose), zolpidem 20 mg, triazolam 0.25 mg (positive control), and placebo. Subjective behavioral ratings and psychomotor tests were completed before and 1.25 and 8.25 hours after administration of the study drug. The Immediate and Delayed Word Recall tests and the Digit Span Test were used to assess memory. The Digit-Symbol Substitution Test, Paired Associates Learning Test, and Divided Attention Test were used to assess other cognitive skills. Zaleplon 10 mg did not produce any significant changes in memory or learning compared with placebo. All other active treatments, including zolpidem 10 mg, caused psychomotor impairment at the 1.25-hour test battery. Zolpidem 20 mg (twice the therapeutic dose) produced more psychomotor impairment at the 1.25-hour assessment than did any of the other active treatments, including zaleplon 20 mg. At the 8.25-hour time point, test scores for subjects who received zaleplon 10 mg and 20 mg did not differ from the test scores for those who received placebo. However, cognitive impairment persisted up to the 8.25-hour observation for subjects who were administered triazolam 0.25 mg and zolpidem 20 mg. Adverse events associated with the use of zaleplon were transient and mild-to-moderate in severity. Overall, this study shows that zaleplon is a safe hypnotic that does not affect memory, learning, or psychomotor skills associated with vigilance.

Zaleplon - a review of a novel sedative hypnotic used in the treatment of insomnia

Zaleplon (N-[3-(3-cyanopyrazolo[1,5-a] pyrimidin-7-yl) phenyl]-N-ethyl acetamide) is a non-benzodiazepine recently introduced for clinical use. This agent is indicated for the short-term treatment of insomnia. Preclinical studies have shown that the benzodiazepines triazolam and Ro17-1812 can substitute for zaleplon in animals trained to distinguish zaleplon from saline. The benzodiazepine antagonist flumazenil can antagonise the discriminative stimulus effect of zaleplon. These findings suggest that zaleplon is recognised by animals as a benzodiazepine agent. Zaleplon is active after ip. and oral administration in a variety of motor performance tests, including locomotor activity, rotarod and the loaded grid. Zaleplon has been shown to be active in a number of different anticonvulsant models, including the pentylenetetrazole, isoniazid and electroshock models. The compound is also reported to be active against convulsions induced by bicuculline, picrotoxin and strychnine. Studies in anxiolytic models suggest that zaleplon may have weak anxiolytic activity. From preclinical studies, it appears zaleplon possesses a reduced risk of tolerance compared to triazolam, is less likely to potentiate the effects of ethanol and is unlikely to produce amnestic effects. In man, zaleplon is rapidly absorbed and undergoes extensive presystemic metabolism. The compound has a plasma half-life of approximately one hour and is metabolised primarily via the aldehyde oxidase system to form 5-oxo-zaleplon. This metabolite, along with other minor metabolites formed in vivo, do not appear to contribute to the activity of zaleplon. Metabolites of zaleplon are excreted primarily via the urine. Phase I studies suggest that single daytime doses of zaleplon up to 15 mg are well-tolerated. Short-term impairment of performance occurs when zaleplon is administered during the day at doses epsilon 20 mg. However, given the short half-life of the compound, significant impairment of daytime performance is unlikely if zaleplon is administered at bedtime or shortly after retiring for the evening. Results from Phase II/III studies suggest that zaleplon (5 - 20 mg) produces a dose-dependent reduction in sleep latency in patients suffering from primary insomnia. The clinical efficacy of zaleplon persists for at least four weeks at doses of 10 mg and 20 mg. Studies in patients with a history of drug abuse suggest that the abuse potential of zaleplon (at doses above the therapeutic dose range) is similar to that seen with the benzodiazepine triazolam.

Zaleplon

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Management of insomnia

OBJECTIVE

To review current issues in the pharmacologic and nonpharmacologic management of insomnia.

DATA SOURCES

Controlled trials and case studies identified via MEDLINE for 1990 through April 1999 under the search terms insomnia, hypnotics, flurazepam, quazepam, estazolam, temazepam, triazolam, zolpidem, zaleplon, L-846, CL-284,846, melatonin, and valerian.

DATA SYNTHESIS

Insomnia is a common, undertreated disorder. Nonpharmacologic management strategies (e.g., stimulus control, relaxation therapy, sleep hygiene) are therapeutic options that, compared with medication use, provide more sustained effects. The benzodiazepines and zolpidem are the most commonly prescribed hypnotic agents, but their use is associated with tolerance and central nervous system adverse effects. A new nonbenzodiazepine hypnotic agent, zaleplon, was very recently approved in the United States. Because of its short half-life, zaleplon will be useful in patients experiencing difficulty in falling asleep and in those who wake up at night and have trouble falling back to sleep. Antidepressants, antihistamines, and alternative medications are other treatment options. To avoid complications of therapy, hypnotic agents should be used at their lowest possible doses and for limited treatment durations.

CONCLUSION

Pharmacotherapy is currently the most common treatment modality for insomnia, but long-term use of hypnotic agents can become complicated by drug tolerance, dependence, or rebound insomnia. Nonpharmacologic options--including combinations of behavioral interventions, sleep-restriction therapy, and patient education--provide longer-lasting benefits.

A comparison of the residual effects of zaleplon and zolpidem following administration 5 to 2 h before awakening

AIMS

To compare the duration of the residual hypnotic and sedative effects of zaleplon with those of zolpidem and placebo following nocturnal administration at various times before morning awakening.

METHODS

Zaleplon 10 mg, zolpidem 10 mg, or placebo was administered double-blind to 36 healthy subjects under standardized conditions in a six-period, incomplete-block, crossover study. Subjects were gently awakened and given medication at predetermined times 5, 4, 3, or 2 h before morning awakening, which occurred 8 h after bedtime. When the subjects awoke in the morning, a battery of subjective and objective assessments of residual effects of hypnotics was administered.

RESULTS

No residual effects were demonstrated after zaleplon 10 mg, when administered as little as 2 h before waking, on either subjective or objective assessments, whereas zolpidem 10 mg showed significant residual effects on DSST and memory (immediate and delayed free recall) after administration up to 5 h before waking and choice reaction time, critical flicker fusion threshold and Sternberg memory scanning after administration up to 4 h before waking. Residual effects of zolpidem were apparent in all objective and subjective measurements when the drug was administered later in the night.

CONCLUSIONS

The present results demonstrate that zaleplon at the dose of 10 mg is free of residual hypnotic or sedative effects when administered nocturnally as little as 2 h before waking in normal subjects. In contrast, residual effects of zolpidem are still apparent on objective assessments up to 5 h after nocturnal administration, longer than has been reported from studies involving daytime administration.

Zaleplon, A Novel Nonbenzodiazepine Hypnotic, Effectively Treats Insomnia in Elderly Patients Without Causing Rebound Effects

BACKGROUND: Insomnia is a very common symptom, particularly in the elderly. Thus, all hypnotic medications should be carefully evaluated in the elderly population. Zaleplon, a new nonbenzodiazepine hypnotic with a short elimination half-life (approximately 1 hour), was evaluated in the current study. METHOD: This multicenter, randomized, placebo-controlled outpatient study evaluated the efficacy and safety of zaleplon, 5 and 10 mg, in elderly patients with insomnia (as defined by DSM-IV); zolpidem, 5 mg, was the active comparator. Sleep was assessed in 549 elderly patients (>/= 65 years old) by using morning questionnaires completed after each of 7 baseline nights during which placebo was given, 14 nights of double-blind treatment, and 7 nights of placebo after discontinuation of active treatment. RESULTS: Zaleplon, 10 mg, and zolpidem, 5 mg, significantly reduced sleep latency during both weeks of the study. Zaleplon, 5 mg, reduced sleep latency only during week 2. Sleep duration was increased with zolpidem, 5 mg, during weeks 1 and 2 and with zaleplon, 10 mg, during week 1. No clinically significant rebound insomnia was observed after discontinuation of treatment with zaleplon, whereas evidence of rebound effects was seen with zolpidem. There was no significant difference between either zaleplon dose and placebo in the frequency of any central nervous system adverse events. CONCLUSION: Zaleplon is effective in reducing latency to sleep without evidence of undesired effects in elderly patients with insomnia.

Rapid disappearance of zaleplon from breast milk after oral administration to lactating women

Five lactating mothers were administered the therapeutic dose of zaleplon (10 mg) orally in an open-label, single-dose, pharmacokinetic study. Plasma and breast milk were sampled through 8 hours after dose administration for subsequent determinations of zaleplon and its major, though inactive, plasma metabolite 5-oxo-zaleplon. Zaleplon concentrations peaked in plasma and milk approximately 1 hour after dosing and then disappeared rapidly. The mean terminal half-life was slightly greater than 1 hour. Milk concentrations "mirrored" plasma concentrations closely with no discernible delay between peak times. The average milk-to-plasma (M/P) concentration ratio for zaleplon was approximately 0.50 over the time course. 5-oxo-zaleplon was undetectable in all but one milk sample. The maximum exposure of an infant to zaleplon during a feeding at peak milk concentrations was estimated to range from 1.28 micrograms to 1.66 micrograms, corresponding to 0.013% to 0.017% of the maternal dose or 0.320 microgram/kg to 0.415 microgram/kg for a 4 kg infant. The results indicate that zaleplon taken by a nursing mother is transferred through breast milk to her infant in very small quantities that are unlikely to be clinically important.

Zaleplon pharmacokinetics and absolute bioavailability

The pharmacokinetics and absolute oral bioavailability of zaleplon were assessed to evaluate the extent of presystemic metabolism of this new nonbenzodiazepine hypnotic agent. A partially randomized, single-dose, four-period crossover study was conducted in 23 healthy subjects. Subjects received 1 and 2.5 mg intravenous (i.v.) infusions of zaleplon during the first and second periods, respectively, and then were randomly assigned to receive a 5 mg oral dose or 5 mg i.v. infusion of zaleplon in a crossover design during the final two periods. Zaleplon pharmacokinetics were determined in 20 subjects (ten men and ten women) after the two 5 mg treatments. The oral and i.v. doses of zaleplon administered in this study were safe and well-tolerated. Following i.v. administration, zaleplon had a moderate to high systemic clearance (mean +/- S.D., 0.94 +/- 0.20 L/h/kg), rapid elimination (half-life, t1/2 = 1.05 +/- 0.13 h), and a steady-state volume of distribution of 1.27 +/- 0.25 L/kg, indicating substantial distribution into extravascular tissues. Zaleplon was rapidly absorbed after oral administration, and the mean apparent elimination t1/2 was similar to that obtained after i.v. infusion. The absolute bioavailability was 30.6 +/- 10.2%.