Zolpidem, triazolam, and temazepam: behavioral and subject-rated effects in normal volunteers

Total Sleep Time Interacts With Age to Predict Cognitive Performance Among Adults

STUDY OBJECTIVES

To investigate interactions between high and low amounts of sleep and other predictors of cognitive performance.

METHODS

We used four cognitive tests to determine whether sleep time interacted with age, personal history of a memory problem, parental history of a memory problem, or personal concerns about memory and were associated with cognitive performance. Data were collected from an internet-based cohort study. We used an ordinary least squares regression with restricted cubic splines, controlling for demographic variables and comorbidities.

RESULTS

We found significant nonlinear interactions between (1) total sleep time and age and (2) total sleep time and personal history of a memory problem and cognitive performance. Short and long sleep durations and self-reported memory complaints were associated with poorer performance on a test of attention and this was true to a greater degree in younger and older adults. A repeat analysis excluding subjects reporting dementia was significant only for the test of attention.

CONCLUSIONS

These results extend existing data on sleep duration and cognition across the lifespan by combining in a single study the results from four specific cognitive tests, both younger and older adults, and four self-reported risk factors for cognitive impairment. Longitudinal studies with biomarkers should be undertaken to determine whether causal mechanisms, such as inflammation or amyloid buildup, account for these associations.

Toward evidence-based prescribing at end of life: A comparative review of temazepam and zolpidem for the treatment of insomnia

A comparative review of temazepam and zolpidem use in managing insomnia in the hospice patient was undertaken to determine whether treatment with temazepam is a more cost-effective approach for this patient population.

A MEDLINE search was conducted to identify pertinent literature, including clinical trials and reviews that involved temazepam or zolpidem. Published data was used as background information and provided in the discussion.

This retrospective analysis, conducted from June 2002 through November 2002, focused on the prescribing patterns of temazepam and zolpidem in our hospice practice setting. We examined the reasons for discontinuation of each agent, along with the frequency of therapeutic change from temazepam to zolpidem. The top 10 ICD-9 codes associated with each treatment modality were investigated to determine any prescribing patterns.

A total of 4,752 participants were prescribed either temazepam or zolpidem during this six-month period. Of the 4,065 patients prescribed temazepam 9.9 percent had the agent discontinued, whereas, 13.0 percent of those taking zolpidem (n = 687) terminated therapy. Reasons for discontinuation included change in dose, incomplete efficacy, change in patient status, adverse drug reaction, cultural/social issues and “other.” Analyses of prescribing patterns and the reasons for termination of each drug therapy were completed and compared with results found in the primary literature.

Due to the limited financial resources available for hospice care, our goal is to provide the most clinically appropriate and cost-effective agents for hospice patients. With the lack of data pertaining to the hospice patient, physicians often are faced with challenges in deciding the most appropriate therapy. They may prefer one agent over another based on current medical opinion rather than sound clinical evidence. After review of the primary literature and the prescribing patterns in our setting, there is currently no evidence in our patient population to support that zolpidem is superior to benzodiazepines for the treatment of insomnia.

The effects of acute treatment with ramelteon, triazolam, and placebo on driving performance, cognitive function, and equilibrium function in healthy volunteers

RATIONALE

Hypnotics are widely used to treat insomnia but adverse effects of different hypnotics, especially benzodiazepine receptor agonists, are getting more attention lately. The effects of novel hypnotics have not been fully examined.

OBJECTIVE

This study aims to assess the effects of two hypnotics, ramelteon and triazolam, on driving performance, cognitive function, and equilibrium function.

METHODS

In this double-blinded, three-way crossover trial, 17 healthy males received acute doses of 8 mg ramelteon, 0.125 mg triazolam, and placebo. The subjects were administered three driving tasks-road-tracking, car-following, and harsh-braking-using a driving simulator and three cognitive tasks-Continuous Performance Test, N-back Test, and Trail-Making Test-at baseline and at 1 and 4 h post-dosing. The Stanford Sleepiness Scale scores and computerized posturography were also assessed.

RESULTS

In the driving simulations, ramelteon and triazolam increased the number of subjects who slid off the road. Triazolam increased the standard deviation of lateral position compared to ramelteon and placebo at 1 h post-dosing. Ramelteon and triazolam significantly increased the time to complete of Trail-Making Test part A and the environmental area in posturography compared to placebo at 1 and 4 h post-dosing. Ramelteon and triazolam significantly increased subjective sleepiness compared to placebo at 1 h post-dosing.

CONCLUSIONS

Ramelteon may affect road-tracking performance, visual attention and/or psychomotor speed measured by Trail-Making Test part A, and body balance in acute dosing. Lower dose of triazolam also impaired performance worse than ramelteon. Physicians should consider risks and benefits when prescribing both drugs, especially in the initial period of administration.

Zolpidem increases GABA in depressed volunteers maintained on SSRIs

Individuals with major depressive disorder (MDD) often use hypnotics like zolpidem (Ambien(®)) to improve sleep in addition to their selective serotonin reuptake inhibitor (SSRI) regimen. SSRIs act in part to restore disrupted GABAergic activity, but benzodiazepines and related drugs have been shown to lower GABA in a way that may be counter to these therapeutic effects. The present within-subject, single-blind, placebo-controlled study measured changes in GABA in the anterior cingulate (ACC) and thalamus of volunteers maintained on SSRIs for the treatment of MDD (n=14) following zolpidem (10mg) administration. In addition to neurochemical measurements obtained using proton magnetic resonance spectroscopy ((1)H MRS) at 4 T, a series of questionnaires were administered to assess subjective effects associated with acute zolpidem exposure. Zolpidem elevated GABA levels in both voxels of interest (P<0.05) in the depressed participants, which could imply normalization, given the lower baseline levels associated with depression. The subjective drug experience in the depressed cohort was similar to that reported previously by healthy volunteers, and no relationships existed between GABA increases and the observed behavioral effects. Aside from treating insomnia, using zolpidem in the presence of SSRIs may have some unidentified therapeutic effects for depressed individuals.

Orexin receptor antagonists differ from standard sleep drugs by promoting sleep at doses that do not disrupt cognition

Current treatments for insomnia, such as zolpidem (Ambien) and eszopiclone (Lunesta), are γ-aminobutyric acid type A (GABAA)-positive allosteric modulators that carry a number of side effects including the potential to disrupt cognition. In an effort to develop better tolerated medicines, we have identified dual orexin 1 and 2 receptor antagonists (DORAs), which promote sleep in preclinical animal models and humans. We compare the effects of orally administered eszopiclone, zolpidem, and diazepam to the dual orexin receptor antagonist DORA-22 on sleep and the novel object recognition test in rat, and on sleep and two cognition tests (delayed match to sample and serial choice reaction time) in the rhesus monkey. Each compound's minimal dose that promoted sleep versus the minimal dose that exerted deficits in these cognitive tests was determined, and a therapeutic margin was established. We found that DORA-22 has a wider therapeutic margin for sleep versus cognitive impairment in rat and rhesus monkey compared to the other compounds tested. These data were further supported with the demonstration of a wider therapeutic margin for DORA-22 compared to the other compounds on sleep versus the expression of hippocampal activity-regulated cytoskeletal-associated protein (Arc), an immediate-early gene product involved in synaptic plasticity. These findings suggest that DORAs might provide an effective treatment for insomnia with a greater therapeutic margin for sleep versus cognitive disturbances compared to the GABAA-positive allosteric modulators currently in use.

Atomoxetine does not alter cocaine use in cocaine dependent individuals: double blind randomized trial

BACKGROUND

Cocaine abuse continues to be a significant public health problem associated with morbidity and mortality. To date, no pharmacotherapeutic approach has proven effective for treating cocaine use disorders. Preclinical and clinical evidence suggests that noradrenergic activity may play a role in mediating some effects of cocaine and may be a rational target for treatment.

METHODS

This double blind, placebo-controlled randomized, parallel group, 12-week outpatient clinical trial enrolled cocaine dependent individuals seeking treatment to examine the potential efficacy of the selective norepinephrine reuptake inhibitor, atomoxetine (80 mg/day; p.o.; n = 25), compared to placebo (n = 25). Subjects were initially stratified on cocaine use (< 15 days or ≥ 15 days of the last 30), age and race using urn randomization. Attendance, medication adherence and study compliance were reinforced with contingency management, and weekly counseling was offered. An array of measures (vital signs, laboratory chemistries, cognitive and psychomotor tests, cocaine craving and urine samples for drug testing) was collected throughout the study and at follow-up.

RESULTS

Survival analysis revealed no differences in study retention between the two groups, with approximately 56% of subjects completing the 12-week study (Cox analysis χ(2) = .72; p = .40; Hazard Ratio 1.48 [95% CI 0.62-3.39]). GEE analysis of the proportion of urine samples positive for benzoylecgonine, a cocaine metabolite, revealed no differences between the atomoxetine and placebo groups (χ(2) = 0.2, p = .66; OR = 0.89 [95% CI 0.41-1.74]). Atomoxetine was generally well tolerated in this population.

CONCLUSIONS

These data provide no support for the utility of atomoxetine in the treatment of cocaine dependence.

Insomnia pharmacotherapy

The benzodiazepine receptor agonists (BzRAs) a melatonin receptor agonist and a histamine antagonist have all been approved as hypnotics. Beyond their differing mechanisms of action, they have differences in pharmacokinetics, and among the BzRAs differences in receptor subtype affinity and formulations, which provides the physician with broad options for tailoring therapy to each patient's specific needs. Consistent with their specific pharmacokinetics and formulations, these Food and Drug Administration-approved hypnotics have been shown to improve sleep with no evidence of tolerance development in long-term use. In addition, emerging data indicate these drugs also improve aspects of daytime function. Their side effects are either associated with the direct sedating effects of the drugs, doses greater than clinical doses, or a combination with alcohol or other sedating drugs. Anxiolytic BzRAs, sedating antidepressants and antipsychotics have been used off-label as hypnotics. However, in the absence of information regarding their dose range for efficacy and safety, their use as hypnotics is ill-advised.

Differential roles of GABA(A) receptor subtypes in benzodiazepine-induced enhancement of brain-stimulation reward

Benzodiazepines such as diazepam are widely prescribed as anxiolytics and sleep aids. Continued use of benzodiazepines, however, can lead to addiction in vulnerable individuals. Here, we investigate the neural mechanisms of the behavioral effects of benzodiazepines using the intracranial self-stimulation (ICSS) test, a procedure with which the reward-enhancing effects of these drugs can be measured. Benzodiazepines bind nonselectively to several different GABA(A) receptor subtypes. To elucidate the α subunit(s) responsible for the reward-enhancing effects of benzodiazepines, we examined mice carrying a histidine-to-arginine point mutation in the α1, α2, or α3 subunit, which renders the targeted subunit nonresponsive to diazepam, other benzodiazepines and zolpidem. In wild-type and α1-point-mutated mice, diazepam caused a dose-dependent reduction in ICSS thresholds (reflecting a reward-enhancing effect) that is comparable to the reduction observed following cocaine administration. This effect was abolished in α2- and α3-point-mutant mice, suggesting that these subunits are necessary for the reward-enhancing action of diazepam. α2 Subunits appear to be particularly important, since diazepam increased ICSS thresholds (reflecting an aversive-like effect) in α2-point-mutant animals. Zolpidem, an α1-preferring benzodiazepine-site agonist, had no reward-enhancing effects in any genotype. Our findings implicate α2 and α3 subunit containing GABA(A) receptors as key mediators of the reward-related effects of benzodiazepines. This finding has important implications for the development of new medications that retain the therapeutic effects of benzodiazepines but lack abuse liability.

Zolpidem ingestion, automatisms, and sleep driving: a clinical and legal case series

STUDY OBJECTIVES

To describe zolpidem-associated complex behaviors, including both daytime automatisms and sleep-related parasomnias.

METHODS

A case series of eight clinical patients and six legal defendants is presented. Patients presented to the author after an episode of confusion, amnesia, or somnambulism. Legal defendants were being prosecuted for driving under the influence, and the author reviewed the cases as expert witness for the defense. Potential predisposing factors including comorbidities, social situation, physician instruction, concomitant medications, and patterns of medication management were considered.

RESULTS

Patients and defendants exhibited abnormal behavior characterized by poor motor control and confusion. Although remaining apparently interactive with the environment, all reported amnesia for 3 to 5 hours. In some cases, the episodes began during daytime wakefulness because of accidental or purposeful ingestion of the zolpidem and are considered automatisms. Other cases began after ingestion of zolpidem at the time of going to bed and are considered parasomnias. Risk factors for both wake and sleep-related automatic complex behaviors include the concomitant ingestion of other sedating drugs, a higher dose of zolpidem, a history of parasomnia, ingestion at times other than bedtime or when sleep is unlikely, poor management of pill bottles, and living alone. In addition, similar size and shape of two medications contributed to accidental ingestion in at least one case.

CONCLUSIONS

Sleep driving and other complex behaviors can occur after zolpidem ingestion. Physicians should assess patients for potential risk factors and inquire about parasomnias. Serious legal and medical complications can occur as a result of these forms of automatic complex behaviors.

Zolpidem for insomnia

INTRODUCTION

The imidazopyridine derivative zolpidem , which acts as a benzodiazepine (BZ) receptor agonist, is the most widely prescribed hypnotic drug in the US.

AREAS COVERED

This review addresses the neuroreceptor properties of zolpidem; clinical pharmacokinetics, pharmacodynamics and drug interactions; efficacy as a hypnotic; adverse effects; tolerance, dependence and withdrawal; relation to motor vehicle accidents and complex sleep behaviors; and new dosage forms.

EXPERT OPINION

Approved doses of zolpidem (10 mg for adults, 5 mg for the elderly) are consistently effective in reducing sleep latency and consequently increasing sleep duration in patients with insomnia. However, favorable effects on sleep maintenance are observed less consistently. Residual daytime effects are unlikely with recommended doses, and provided that at least 8 h elapse prior to arising. Hypnotic efficacy is maintained with repeated nightly use, and the risk of rebound insomnia is low. Dependence and abuse of zolpidem are no more likely to occur than with typical benzodiazepines. Newly available novel dosage forms of zolpidem have increased therapeutic options for patients with insomnia variants such as sleep maintenance insomnia and middle-of-the-night awakening.

Modest abuse-related subjective effects of zolpidem in drug-naive volunteers

Recent case reports suggest that the short-acting benzodiazepine-like hypnotic, zolpidem, may have abuse potential among individuals who have no personal history of abusing drugs or alcohol, particularly at doses higher than those recommended for treating insomnia. This study recruited drug-naive volunteers to assess the subjective effects of multiple doses of zolpidem (0, 5, 10, or 20 mg) administered in a within-subject double-blind design. Participants (n=11) answered computerized questionnaires (Addiction Research Center Inventory, visual analog scales, and a hypothetical Drug versus Money Choice) to address the hypothesis that a supratherapeutic dose (20 mg) would increase ratings of abuse-related subjective effects, while lower therapeutic doses (5 and 10 mg) would not. Although participants rated some effects as negative at 10 and 20 mg, the highest dose engendered predominantly positive abuse-like effects such as 'High', 'Like', and 'Good Effects'. However, no dose of zolpidem was chosen over money ($0.35-$10) when participants made hypothetical choices between them. Results suggest that although individuals without a drug abuse history are not inclined to choose zolpidem when presented with an alternative reinforcer such as money, it may possess moderate abuse potential that limits its clinical utility.

Pharmacokinetics, pharmacodynamics and the pharmacokinetic/ pharmacodynamic relationship of zolpidem in healthy subjects

Zolpidem is one of the most frequently prescribed hypnotics, as it is a very short-acting compound with relatively few side effects. Zolpidem's short duration of action is partly related to its short elimination half-life, but the associations between plasma levels and pharmacodynamic (PD) effects are not precisely known. In this study, the concentration-effect relationships for zolpidem were modelled. Zolpidem (10 mg) was administered in a double-blind, randomised, placebo-controlled trial to determine PD and pharmacokinetics (PK) in 14 healthy volunteers. Zolpidem was absorbed and eliminated quickly, with a median T(max) of 0.78 h (range: 0.33-2.50) and t(1/2) of 2.2 h. Zolpidem reduced saccadic peak velocity (SPV), adaptive tracking performance, electroencephalogram (EEG) alpha power and visual analogue scale (VAS) alertness score and increased body sway, EEG beta power and VAS 'feeling high'. Short- and long-term memory was not affected. Central nervous system effects normalised more rapidly than the decrease of plasma concentrations. For most effects, zolpidem's short duration of action could be adequately described by both a sigmoid E(max) model and a transit tolerance model. For SPV and EEG alpha power, the tolerance model seemed less suitable. These PK/PD models have different implications for the mechanism underlying zolpidem's short duration of action. A sigmoid E(max) model (which is based on ligand binding theory) would imply a threshold value for the drug's effective concentrations. A transit tolerance model (in which a hypothetical factor builds up with time that antagonises the effects of the parent compound) is compatible with a rapid reversible desensitisation of GABAergic subunits.

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.

A therapeutic dose of zolpidem reduces thalamic GABA in healthy volunteers: a proton MRS study at 4 T

BACKGROUND

Zolpidem is a nonbenzodiazepine sedative/hypnotic that acts at GABA(A) receptors to influence inhibitory neurotransmission throughout the central nervous system. A great deal is known about the behavioral effects of this drug in humans and laboratory animals, but little is known about zolpidem's specific effects on neurochemistry in vivo.

OBJECTIVES

We evaluated how acute administration of zolpidem affected levels of GABA, glutamate, glutamine, and other brain metabolites.

MATERIALS AND METHODS

Proton magnetic resonance spectroscopy ((1)H MRS) at 4 T was employed to measure the effects of zolpidem on brain chemistry in 19 healthy volunteers. Participants underwent scanning following acute oral administration of a therapeutic dose of zolpidem (10 mg) in a within-subject, single-blind, placebo-controlled, single-visit study. In addition to neurochemical measurements from single voxels within the anterior cingulate (ACC) and thalamus, a series of questionnaires were administered periodically throughout the experimental session to assess subjective mood states.

RESULTS

Zolpidem reduced GABA levels in the thalamus, but not the ACC. There were no treatment effects with respect to other metabolite levels. Self-reported ratings of "dizzy," "nauseous," "confused," and "bad effects" were increased relative to placebo, as were ratings on the sedation/intoxication (PCAG) and psychotomimetic/dysphoria (LSD) scales of the Addiction Research Center Inventory. Moreover, there was a significant correlation between the decrease in GABA and "dizzy."

CONCLUSIONS

Zolpidem engendered primarily dysphoric-like effects and the correlation between reduced thalamic GABA and "dizzy" may be a function of zolpidem's interaction with alpha1GABA(A) receptors in the cerebellum, projecting through the vestibular system to the thalamus.

Effects of prolonged-release melatonin, zolpidem, and their combination on psychomotor functions, memory recall, and driving skills in healthy middle aged and elderly volunteers

BACKGROUND

Melatonin is an important regulator of the sleep-wake cycle. A prolonged-release formulation of melatonin (PR-M) that essentially mimics the profile of the endogenous production of the hormone is effective in the treatment of insomnia in patients aged 55 years and older. Because hypnotics result in impairments of various cognitive skills, it is important to examine the cognitive effects associated with the use of PR-M.

OBJECTIVES AND METHODS

The effects of therapeutic oral doses of PR-M (2 mg), zolpidem (10 mg) and their combination administered at bedtime on cognitive functions in healthy subjects aged 55 years and older (12 males + 4 females, age 59.4 +/- 3.2 years) were assessed in a randomized, double-blind, placebo-controlled, and four-way crossover study. Psychomotor functions, memory recall, and driving skills were assessed at 1 and 4 h following administration and the next morning.

RESULTS

Compared to placebo, PR-M alone did not impaired performances on any cognitive tasks. Zolpidem significantly impaired psychomotor and driving performance 1 h and 4 h post-dosing, and early memory recall; these impairment were exacerbated with PR-M co-administration. No effects on next morning psychomotor or driving performance were observed except that the decline in memory recall after zolpidem was more pronounced in the next day. No pharmacokinetic interactions were found.

CONCLUSIONS

This study extends previous researches showing impairment of cognitive functions by zolpidem within 5 h post-administration. Further, PR-M use was not found associated with impairment of psychomotor functions, memory recall, and driving skills, and point to a pharmacodynamic interaction between melatonin and GABA-A modulators.

A therapeutic dose of zolpidem has limited abuse-like effects in drug-naïve females: a pilot study

Zolpidem has abuse potential, particularly among individuals with histories of drug abuse. This double-blind, placebo-controlled, cross over pilot study investigated the subjective effects of zolpidem (10 mg) in drug-naïve females. Over the course of a 5-h period vital signs were monitored and a series of computerized questionnaires was administered. Results indicate that zolpidem engendered subjective effects characteristic of hypnotic drugs, but reduced ratings of drug liking, willing to take again, and willing to pay for, relative to placebo. Thus, a therapeutic dose of zolpidem may have limited potential for misuse among females who have no experience with drugs of abuse.

Post-bedtime dosing with indiplon in adults and the elderly: results from two placebo-controlled, active comparator crossover studies in healthy volunteers

OBJECTIVE

To assess the effects of post-bedtime dosing with indiplon on next-day function in adults and the elderly.

RESEARCH DESIGN AND METHODS

Two randomized, double-blind, placebo-controlled crossover studies were conducted in two groups of healthy volunteers: an adult study (18-45 years) and an elderly study (65-80 years). In adults, a single post-bedtime dose of indiplon 10 mg and 20 mg was compared to placebo, with zolpidem 10 mg and zopiclone 7.5 mg included as controls. In the elderly, a single post-bedtime dose of indiplon 5 mg and 10 mg was compared to placebo, with zopiclone 3.75 mg included as a control. Next-day residual effects were evaluated in the morning at 4 and 6 h post-dose in adults, and 4, 6, and 8 h in the elderly, by a Visual Analog Scale of sleepiness (VAS-sleepiness), Digit Symbol Substitution Test (DSST), and the Symbol Copying Test (SCT).

RESULTS

In adults, there were no statistically significant differences between indiplon and placebo on the VAS-sleepiness, DSST, or SCT at any time-point for either dose. In contrast, a significant increase versus placebo in VAS-sleepiness was observed for both zopiclone (at 4 and 6 h post-dose; p < 0.0001 and p = 0.002, respectively) and zolpidem (at 4 h post-dose; p = 0.042). In the elderly, there were no statistically significant differences between indiplon 5 mg and placebo on the VAS-sleepiness, DSST, or SCT at any time-point. DSST was significantly reduced for indiplon 10 mg versus placebo at 4 h only (p = 0.022), compared with a significant reduction in DSST for zopiclone at both 4 and 8 h post-dose (p = 0.002 and p = 0.003, respectively). In adults, the overall incidence of adverse events was higher on zopiclone compared to indiplon, zolpidem, and placebo. In the elderly, the incidence of adverse events was similar for indiplon, zopiclone, and placebo. Potential limitations of the current study include recruitment of healthy volunteers and the use of a limited pharmacodynamic battery.

CONCLUSIONS

Indiplon, at doses of 10 mg in adults and 5 mg in the elderly, was not associated with next day residual sedation or impairment in simple cognitive and psychomotor tasks when administered during the night 4 h prior to awakening.

Pharmacokinetic and Pharmacodynamic Interactions Between Zolpidem and Caffeine

The kinetic and dynamic interaction of caffeine and zolpidem was evaluated in a double-blind, single-dose, six-way crossover study of 7.5 mg zolpidem (Z) or placebo (P) combined with low-dose caffeine (250 mg), high-dose caffeine (500 mg), or placebo. Caffeine coadministration modestly increased maximum plasma concentration (C(max)) and area under the plasma concentration-time curve of zolpidem by 30-40%, whereas zolpidem did not significantly affect the pharmacokinetics of caffeine or its metabolites. Compared to P+P, Z+P significantly increased sedation, impaired digit-symbol substitution test performance, slowed tapping speed and reaction time, increased EEG relative beta amplitude, and impaired delayed recall. Caffeine partially, but not completely, reversed most pharmacodynamic effects of zolpidem. Thus, caffeine only incompletely reverses zolpidem's sedative and performance-impairing effects, and cannot be considered as an antidote to benzodiazepine agonists.

Discriminative-stimulus effects of triazolam in women and men

Benzodiazepines are among the most commonly prescribed therapeutics. Women seem to be more likely than men to be prescribed a benzodiazepine and to use benzodiazepines for nonmedical reasons; they also appear to be at higher risk for benzodiazepine dependence. The aim of the present investigation was to assess the acute behavioral effects of a benzodiazepine in women and men. To accomplish this, 13 volunteers (6 women, 7 men) first learned to discriminate 0.375-mg triazolam, a triazolobenzodiazepine hypnotic. After acquiring the discrimination, (i.e., >80% correct responding on 4 consecutive sessions) a range of doses of triazolam (0, 0.0625, 0.125, 0.25, and 0.375 mg) were tested in each participant. Triazolam dose dependently increased drug-appropriate responding and subject ratings of sedation and impaired performance (i.e., significant effect of dose). The women and men did not differ significantly on any measure. The results of the present experiment suggest that women and men are not differentially sensitive to the behavioral effects of triazolam.

Application of a computational decision model to examine acute drug effects on human risk taking

In 3 previous experiments, high doses of alcohol, marijuana, and alprazolam acutely increased risky decision making by adult humans in a 2-choice (risky vs. nonrisky) laboratory task. In this study, a computational modeling analysis known as the expectancy valence model (J. R. Busemeyer & J. C. Stout, 2002) was applied to individual-participant data from these studies, for the highest administered dose of all 3 drugs and corresponding placebo doses, to determine changes in decision-making processes that may be uniquely engendered by each drug. The model includes 3 parameters: responsiveness to rewards and losses (valence or motivation); the rate of updating expectancies about the value of risky alternatives (learning/memory); and the consistency with which trial-by-trial choices match expected outcomes (sensitivity). Parameter estimates revealed 3 key outcomes: Alcohol increased responsiveness to risky rewards and decreased responsiveness to risky losses (motivation) but did not alter expectancy updating (learning/memory); both marijuana and alprazolam produced increases in risk taking that were related to learning/memory but not motivation; and alcohol and marijuana (but not alprazolam) produced more random response patterns that were less consistently related to expected outcomes on the 2 choices. No significant main effects of gender or dose by gender interactions were obtained, but 2 dose by gender interactions approached significance. These outcomes underscore the utility of using a computational modeling approach to deconstruct decision-making processes and thus better understand drug effects on risky decision making in humans.

The relationship between performance on the standardised field sobriety tests, driving performance and the level of Δ9-tetrahydrocannabinol (THC) in blood

The consumption of Delta9-tetrahydrocannabinol (THC) as cannabis has been shown to result in impaired and culpable driving. Testing drivers for the presence of THC in blood is problematic as THC and its metabolites may remain in the blood for several days following its consumption, even though the drug may no longer have an influence on driving performance. In the present study, the aim was to assess whether performance on the standardised field sobriety tests (SFSTs) provides a sensitive measure of impaired driving behaviour following the consumption of THC. In a repeated measures design, 40 participants consumed cigarettes that contained either 0% THC (placebo), 1.74% THC (low dose) or 2.93% THC (high dose). For each condition, after smoking a cigarette, participants performed the SFSTs on three occasions (5, 55 and 105 min after the smoking procedure had been completed) as well as a simulated driving test on two occasions (30 and 80 min after the smoking procedure had been completed). The results revealed that driving performance was not significantly impaired 30 min after the consumption of THC but was significantly impaired 80 min after the consumption of THC in both the low and high dose conditions. The percentage of participants whose driving performance was correctly classified as either impaired or not impaired based on the SFSTs ranged between 65.8 and 76.3%, across the two THC conditions. The results suggest that performance on the SFSTs provides a moderate predictor of driving impairment following the consumption of THC and as such, the SFSTs may provide an appropriate screening tool for authorities that wish to assess the driving capabilities of individuals suspected of being under the influence of a drug other than alcohol.

Acute neurophysiological effects of the hypnotic zolpidem in healthy volunteers

INTRODUCTION

The imidazopyridine zolpidem is a hypnotic drug with relative selectivity for the benzodiazepine (BZP) type 1 receptor subtypes displaying a different biochemical structure to that of BZPs. Little is known of its electrophysiological effects.

PURPOSE

The aim of the present study was to investigate the acute neurophysiological effects of clinical oral doses of zolpidem.

METHODS

This was a double blind, independent group design study. Thirty-six young, healthy volunteers were randomly allocated to one of three groups--zolpidem (5 mg and 10 mg) and placebo. In addition to ERPs, behavioural measures were used to examine sedative effects of the drug.

RESULTS

ERPs were affected in a similar way to that described after sedative/hypnotic drug ingestion: increased N2 and P3 latencies and decreased N2 and P3 amplitudes. However, contrary to what is expected of a hypnotic drug, there was no change with N1 while P2 amplitude increased after the highest dose.

CONCLUSIONS

Because zolpidem showed different effects in different components, it seems to first enhance or preserve initial orienting (no change in N1), after an increase of P2 and then drastically diminish resource allocation (affecting N2 and P3 latencies and amplitudes). The study with ERPs, therefore, allows a more direct "moment to moment" investigation of finer mechanisms of changes in cerebral processes underlying the acute ingestion of the drug in question. The effects on N2 and P3 amplitudes and latencies were similar to those of other sedative/hypnotic drugs. However, zolpidem led to an unexpected increase in P2 amplitude; this effect may be related to its selective receptor binding profile and warrants further research.

Temporal changes in postural sway caused by ultrashort-acting hypnotics: triazolam and zolpidem

Two ultrashort-acting hypnotics, triazolam 0.25 mg and zolpidem 10 mg, were studied for their effects on equilibrium function in humans. Eight healthy male subjects participated in a double-blind, placebo-controlled study after informed consent. They subjected to static equilibrium tests, oculomotor tests and an assay of drug concentrations in the blood. Zolpidem was statistically significant in postural sway in tandem stance test, as defined by parametric values of tracing sum length and polygonal area of foot pressure center measured by a gait analysis system. In the tandem stance test, triazolam was statistically significant in postural sway only as defined by the polygonal area. However, in the Romberg test, the only statistically significant difference in zolpidem use was observed in polygonal area values. Blood concentrations of triazolam and zolpidem were found to closely correlate with the extent of postural sway in both tandem stance and Romberg tests. In this study, zolpidem with minimal muscle-relaxant effect incurred imbalance more extensively than triazolam, which is known for its effect of muscle relaxation. In addition, gaze deviation nystagmus was observed only in zolpidem use in 5 of 8 subjects (62.5%). From these results, it is suggested that in the use of hypnotics, sway derives from the suppression of the central nervous system relevant to awakening rather than from muscle relaxation. The prior reference to blood concentrations of hypnotics should help improve safety care in minimizing loss of balance control and possible fall.

Zolpidem: a review of its use in the management of insomnia

Zolpidem (Ambien, Stilnox, Myslee, an imidazopyridine, is a nonbenzodiazepine hypnotic indicated for the short-term treatment of insomnia. Zolpidem improves sleep in patients with insomnia. Its overall tolerability is favourable when administered according to the manufacturer's prescribing information, with a low propensity to cause clinical residual effects, withdrawal, dependence or tolerance. In addition, most evidence suggests that the drug is associated with minimal rebound insomnia. In the only clinical trials that investigated the use of a hypnosedative drug in an 'as-needed' regimen, zolpidem produced a global improvement in sleep. Thus, zolpidem continues to be a useful therapeutic option in the pharmacological treatment of patients with insomnia.

Correlates and consequences of chronic insomnia

Approximately one half of patients with insomnia have a primary psychiatric disorder such as a depression or anxiety. Insomnia is associated with increased risk of new or recurrent psychiatric disorders, increased daytime sleepiness with consequent cognitive impairment, poorer prognoses, reduced quality of life and high healthcare-related financial burden. Emerging data suggest that resolution of insomnia may improve psychiatric outcomes, which underscores the importance of vigorous treatment. Unfortunately, only a small percentage of patients receive such care. An ideal monotherapeutic strategy would treat both depression and insomnia. There are, however, only a handful of modern antidepressants that objectively improve sleep maintenance problems, and none do so without causing adverse next-day effects such as sedation. Thus, a significant number of patients must take adjunctive hypnotic medications, even though longer-term efficacy has not been established. New and emerging anti-insomnia agents may prove useful in the long-term treatment of chronic insomnia. Further research is needed to establish the benefits of such treatment.

Current patterns and future directions in the treatment of insomnia

BACKGROUND

Despite the high prevalence and the high burden associated with chronic insomnia, it remains largely unrecognized and often inadequately treated by physicians.

METHODS

A review was undertaken of the literature on barriers to both acute and chronic treatment of insomnia, as well as recent trials of pharmacologic and nonpharmacologic agents for insomnia.

RESULTS

Obstacles to appropriate treatment of the condition include outdated insomnia management guidelines, which have contributed to US Food and Drug Administration restrictions on longer-term prescription of hypnotic agents; lack of research demonstrating the benefit of treating insomnia; and fears of tolerance and withdrawal effects of long-term use of hypnotic agents, as well as an absence of longer-term, randomized, controlled, double-blind trials of existing agents used to treat insomnia.

CONCLUSIONS

There is evidence that improved sleep may improve outcome in some medical and psychiatric illnesses. Both behavioral and pharmacologic therapies have shown efficacy in chronic insomnia. In addition, a recent 6-month, randomized, controlled study has demonstrated that at least one agent may be safe and effective in longer-term use.

Efficacy and safety of eszopiclone across 6-weeks of treatment for primary insomnia

OBJECTIVE

Eszopiclone is a new, single-isomer, non-benzodiazepine, cyclopyrrolone agent under investigation for the treatment of insomnia. The present study was a randomized, double-blind, multicenter, placebo-controlled trial conducted to assess the efficacy and safety of eszopiclone in adults with chronic primary insomnia.

RESEARCH DESIGN AND METHODS

Patients (n = 308) were randomized to receive placebo or eszopiclone (2 mg or 3 mg) for 44 consecutive nights, followed by 2 nights of single-blind placebo. Efficacy was evaluated with polysomnography (Nights 1, 15 and 29) and patient-reports (Nights 1, 15, 29 and 43/44). Next-day residual effects were evaluated using the Digit-Symbol Substitution Test (DSST).

RESULTS

Eszopiclone 3 mg had significantly less time to sleep onset (p < or = 0.0001), more total sleep time and sleep efficiency (p < or = 0.0001), better sleep maintenance (p < or = 0.01), and enhanced quality and depth of sleep (p < 0.05) across the double-blind period compared with placebo. Eszopiclone 2 mg had significantly less time to sleep onset (p < or = 0.001), more total sleep time (p < or = 0.01) and sleep efficiency (p < or = 0.001), and enhanced quality and depth of sleep (p < 0.05) compared with placebo, but did not significantly improve sleep maintenance. There was no evidence of tolerance or rebound insomnia after therapy discontinuation. Median DSST scores showed no decrement in psychomotor performance relative to baseline and did not differ from placebo in either eszopiclone group. Treatment was well tolerated; the most common adverse event related to eszopiclone was unpleasant taste.

CONCLUSIONS

Patients treated with nightly eszopiclone 3 mg had better polysomnographic (through Night 29) and patient-reported measures (through Night 44) of sleep over the 6-week trial. There was no evidence of tolerance or rebound insomnia and no detrimental effects on next-day psychomotor performance using the DSST.

Zolpidem is not superior to temazepam with respect to rebound insomnia: a controlled study

This randomised controlled trial was conducted to compare zolpidem to an equivalent dose of temazepam with respect to subjective rebound insomnia after cessation of 4 weeks of treatment in chronic insomnia (zolpidem 10 mg, n=79; temazepam 20 mg, n=84). Both agents improved total sleep time (TST) as well as sleep onset latency (SOL) significantly during the 4 treatment weeks. Prevalence rates for rebound insomnia, defined as a worsening of TST or SOL of more than 40% compared to baseline, were 27% for TST and 53% for SOL in the Zolpidem condition and 26% and 58%, respectively, in the temazepam condition. No significant differences were found between both agents with respect to rebound insomnia, nor with respect to their efficacy or safety. We conclude that in clinical practice zolpidem has no advantages over temazepam with respect to rebound insomnia.

Residual effects of hypnotics: epidemiology and clinical implications

The risk of "hangover" effects, e.g. residual daytime sleepiness and impairment of psychomotor and cognitive functioning the day after bedtime administration, is one of the main problems associated with the use of hypnotics. However, the severity and duration of these effects varies considerably between hypnotics and is strongly dependent on the dose administered. This article reviews epidemiological evidence on the effect of hypnotics on patients' risk for accidents such as traffic accidents, falls and hip fractures (i.e. end-points for residual effects). Information on the duration and severity of residual effects of 11 hypnotics (flunitrazepam, flurazepam, loprazolam, lormetazepam, midazolam, nitrazepam, temazepam, triazolam, zaleplon, zolpidem and zopiclone) was derived from expert ratings, a meta-analysis and actual driving studies. Epidemiological studies show that the risks of an accident increase with increasing half-life of the hypnotic, but that the use of hypnotics with a short half-life, such as triazolam, zopiclone and zolpidem, can also be associated with increased risks. A summary of results from experimental studies should enable prescribing clinicians to compare residual effects of the various hypnotics at different doses and select the one considered most favourable in this respect for the individual patient. This information should also enable them to inform patients more adequately about the likelihood and duration of residual effects of a specific hypnotic dose.

Methylphenidate Does Not Improve Cognitive Function in Healthy Sleep-Deprived Young Adults

Background

Abuse of methylphenidate, a treatment of attention-deficit/hyperactivity disorder, is reported to be increasing among students for the purpose of improving cognition.

Methods

A single capsule, containing methylphenidate (20 mg) or placebo, was administered to healthy young adults orally following 24 hours of sleep deprivation. Measurements included percent change in score from sleep-deprived baseline on four standardized tests of cognitive function: Hopkins Verbal Learning, Digit Span, Modified Stroop, and Trail Making tests. Measurements also included percent changes in blood pressure and heart rate from sleep-deprived baseline and plasma methylphenidate concentration.

Results

Differences in cognitive test performance were not observed between intervention groups. In subjects receiving methylphenidate, mean percent changes from baseline for systolic blood pressure and heart rate were increased relative to placebo between 90 and 210 minutes following capsule administration (maximum increases of 9.45% and 11.03%, respectively). The timing of peak differences in physiologic measures did not correlate with peak serum methylphenidate concentrations. Exit questionnaire ratings of “capsule effect” and perceived performance on the postcapsule administration of the most challenging cognitive test were both higher ( p = .044 and p = .009, respectively) for the methylphenidate group than for the placebo group. Conclusions: Cognitive improvement among sleep-deprived young adults was not observed following methylphenidate administration. Benefits perceived by abusers may relate to increased confidence and sense of well-being, as well as to sympathetic nervous system stimulation. Moreover, methylphenidate administration results in physiologic effects that could be harmful to certain individuals.

Effects of after-midnight intake of zolpidem and temazepam on driving ability in women with non-organic insomnia

BACKGROUND

Occasionally, insomniac patients may take a sleeping pill after midnight. This may have consequences on their ability to drive a car and result in an increased risk of car accidents.

METHODS

This double-blind, randomized, placebo-controlled, three-treatment three-period cross-over study investigated the effects of two frequently prescribed hypnotics of different classes in a real life condition on driving performance and psychomotor skills in insomniac women. Single doses of zolpidem 10 mg (Z), temazepam 20 mg (T) or placebo (P) were administered at 2:00 a.m. to 19 women aged 35-60 years in three treatment periods separated by wash-out periods of 3-14 days. After polysomnography at baseline and each treatment night, patients underwent, 5.5 h after drug intake at 7:30 a.m. on the next morning, a STISIM driving simulator test, and a subsequent neuropsychological test (FePsy).

RESULTS

Eighteen insomniac women were included in the analysis (mean age 50 years, mean weight 69 kg, mean BMI 25.6 kg/m2). There were no differences between treatments for the primary outcome measure (mean time to collision; baseline: 0.120 s, P: 0.124, T: 0.118, Z: 0.124; P> or =0.12 for all pairwise comparisons). No differences were recorded for speed deviation and reaction time to tasks for the verum treatments, however, lane position deviation was greater after administration of zolpidem in comparison to both placebo and temazepam (P=0.025 and 0.05, respectively). There were no differences between treatments in the FePsy test. Both medications were well tolerated.

CONCLUSIONS

5.5 h after drug administration there were no major differences in psychomotor performances between both zolpidem and temazepam compared to placebo, which indicates the absence of significant residual effects at that time. However, certain patients were more susceptible than others to the drug effects (two patients with high number of collisions). This underlines the necessity to strongly advocate against the late intake of hypnotics if patients intend to drive a car early the next morning.

Comparative cognitive and psychomotor effects of single doses of Valeriana officianalis and triazolam in healthy volunteers

OBJECTIVES

To assess the cognitive and psychomotor effects of single oral doses of valerian in healthy volunteers in comparison with a placebo and the hypnotic agent triazolam.

METHODS

In a double-blind, placebo-controlled, four-way crossover study nine healthy subjects (5 males, 4 females) received in random order valerian 500 mg, valerian 1000 mg, triazolam 0.25 mg and placebo. Doses were separated by a wash-out period of at least 1 week. Subjects were tested before each dose and at 2, 4 and 8 h after the dose of each compound using the critical flicker fusion (CFF), choice reaction time (CRT), digit symbol substitution test (DSST), symbol search test (SST), digit span test (DST) and visual analogue scales of mood.

RESULTS

Repeated measures ANOVA was used to examine the changes in performance on tests over time and significant effects were further analysed using simple main effects analysis with least significant difference corrections. Statistically significant differences were only noted for the cognitive tests: SST (F(3, 8)=3.182, p<0.05) and DSST (F(3, 8)=9.688, p<0.005). In both cases the differences between groups were due to the effects of triazolam.

CONCLUSION

These data confirm that at recommended therapeutic doses, triazolam has detrimental effects on cognitive processes in healthy volunteers as found in previous studies. Valerian was without effect on either cognitive or psychomotor performance in healthy volunteers at the doses used in this study. Should the hypnotic activity of valerian be confirmed in randomized double-blind trials it may be a less troublesome alternative to benzodiazepines in the treatment of insomnia.

Zolpidem-related effects on performance and mood during simulated night-shift work

The effects of zolpidem, a nonbenzodiazepine hypnotic, on psychomotor task performance, subjective effects, and food intake were examined during simulated shift work. Seven participants completed this 23-day, within-participant design, residential laboratory study. They received a single oral zolpidem dose (0, 5, or 10 mg) 1 hr before bedtime for 3 consecutive days under 2 shift conditions: day shift and night shift. When participants received placebo, next-day performance and subjective effects were disrupted, and food intake was decreased during the night shift. Zolpidem improved subjective reports of sleep quality and, to a lesser extent, next-day performance. Next-day mood, however, was worsened by zolpidem. Food intake was unaffected by zolpidem. These data indicate that shift changes produce performance impairments, mood alterations, and decreases in food intake, and that zolpidem attenuates some shift-change-related disruptions.

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.

Acute pharmacological effects of temazepam, diphenhydramine, and valerian in healthy elderly subjects

Elderly insomniacs are often treated pharmacologically with benzodiazepines, antihistamines, or natural products. A double-blind, randomized, crossover, placebo-controlled study was performed to assess the comparative pharmacodynamics of single doses of temazepam (15 and 30 mg), diphenhydramine (50 and 75 mg), and valerian (400 and 800 mg) in 14 healthy elderly volunteers (mean age, 71.6 years; range, 65-89). Assessments were made at 0, 0.5, 1, 2, 3, 4, 6, and 8 hours postdosing with use of validated measures of subjective sedation and mood (visual analogue scales, Tufts University Benzodiazepine scale) and psychomotor performance (manual tracking and digit symbol substitution tests). Temazepam had dose-dependent effects on sedation and psychomotor ability with a distinct time course. Temazepam 30 mg had the most detrimental effect on psychomotor ability (p < 0.001 compared with all other treatments). Temazepam 30 mg and both doses of diphenhydramine elicited significantly greater sedation than placebo (p < 0.05, all), and temazepam had the greatest effect. There was no difference in sedation scores between 50 and 75 mg diphenhydramine. Sedative effects were slightly lesser with 15 mg temazepam and were not significant in comparison with placebo. Psychomotor impairment was evident after administration of 75 mg diphenhydramine in comparison with placebo on the manual tracking test (p < 0.05); this was less than the impairment with 30 mg temazepam (p < 0.001) but similar to that with 15 mg temazepam (NS). No psychomotor impairment was detected with 50 mg diphenhydramine. Valerian was not different from placebo on any measure of psychomotor performance or sedation.

Zolpidem dependence case series: possible neurobiological mechanisms and clinical management

Zolpidem is a short-acting imidazopyridine hypnotic that is an agonist at the gamma-aminobutyric acid A type (GABAA) receptor. It has been suggested that it acts selectively on alpha1 subunit-containing GABAA benzodiazepine (BZ1) receptors presenting (contrary to classic benzodiazepines) low or no affinity for other subtypes. Therefore, it has been proposed that it lacks the benzodiazepines-like side-effects, having minimal abuse and dependence potential. Nevertheless, there is a considerable number of zolpidem dependence case reports in the literature. We present eight cases of zolpidem abuse and dependence without criminal record, without history of substance abuse (except for one alcohol abuser), with minor psychiatric disorders, who took zolpidem after physicians prescription in order to deal with their insomnia. However, they became zolpidem abusers not craving its sedative, but its anxiolytic and stimulating action, which helped them to cope with everyday activities. It is possible that, in the high doses that our patients used, zolpidem abandons its selectivity for BZ1 receptors and demonstrates all the actions of classic benzodiazepines. Molecular biology, via possible mutations on GABA receptors, may provide some answers as to why our eight patients (who did not differ much from the thousands of insomniacs who use zolpidem) and other zolpidem abusers, raised the dose progressively, and sought something from the drug other than hypnotic action.

The effect of zolpidem on operant behavior and its relation to pharmacokinetics after intravenous and subcutaneous administration: concentration-effect relations

We characterized the effects of i.v. and s.c. zolpidem (1-8 mg/kg) under a differential reinforcement of low-rate schedule (i.e. DRL 45 s) in 3-hour sessions. Both behavioral and pharmacokinetic-pharmacodynamic analyses were used with the intent to compare the effects of zolpidem with those of benzodiazepines reported previously under the same behavioral paradigm. Zolpidem increased the shorter-response [inter-response times (IRTs)<45 s] rate and decreased the reinforcement rate in a dose- and time-related fashion. The behavioral profiles of zolpidem were mainly similar to those of benzodiazepines, except zolpidem produced far fewer shorter IRT responses. Pharmacokinetically, zolpidem decays biexponentially with distributional and terminal elimination half-lives of 5.2 and 42 min, respectively. The absorption rate constant and absolute bioavailability for s.c. zolpidem were 0.083/min and of 84.1%, respectively. The pharmacodynamic parameters for the reinforcement rate, an index of timing performance, were determined by integration of behavioral and pharmacokinetic profiles in a between-subject design using the effect-linked inhibitory sigmoidal E(max) model. The pharmacokinetic-pharmacodynamic analysis revealed that the potency of zolpidem (concentration required to produce 50% maximal effects, IC(50)) in disrupting the timing performance was 0.129 microg/ml. The pharmacodynamic estimates of zolpidem were compared to our previous results for benzodiazepines.

Acute performance-impairing and subject-rated effects of triazolam and temazepam, alone and in combination with ethanol, in humans

The acute behavioural effects of triazolam (0.125 and 0.25 mg), temazepam (15 and 30 mg), and placebo, alone and in combination with ethanol (0 and 0.5 g/kg), were assessed in 10 volunteers. Ethanol alone did not impair performance and produced only a few subject-rated drug effects. Triazolam and temazepam alone produced some performance impairment and a few subject-rated drug effects. These effects tended to be dose-dependent and were comparable for the two drugs across the range of doses tested. The triazolam-ethanol and temazepam-ethanol combinations produced robust performance impairment and sedative-like subject-rated drug effects that were similar in magnitude. The findings of the present study suggest that even a moderate amount of ethanol in combination with a clinical dose of triazolam or temazepam can cause performance impairment that might diminish an individual's ability to respond adequately to unexpected demands (e.g. smoke alarms or middle-of-the-night child care).

Discriminative stimulus effects of benzodiazepine (BZ)(1) receptor-selective ligands in rhesus monkeys

Drug discrimination was used to examine the effects of benzodiazepine (BZ)(1) receptor-selective ligands in rhesus monkeys. In diazepam-treated (5.6 mg/kg, p.o.) monkeys discriminating the nonselective BZ antagonist flumazenil (0.32 mg/kg, s.c.), the BZ(1)-selective antagonist beta-carboline-3-carboxylate-t-butyl ester (beta-CCt) substituted for flumazenil. The onset of action of beta-CCt was delayed with a dose of 5.6 mg/kg beta-CCt substituting for flumazenil 2 h after injection. In monkeys discriminating the nonselective BZ agonist midazolam (0.56 mg/kg, s.c.), the BZ(1)-selective agonists zaleplon (ED(50) = 0.78 mg/kg) and zolpidem (ED(50) = 1.73 mg/kg) substituted for midazolam. The discriminative stimulus effects of midazolam, zaleplon, and zolpidem were antagonized by beta-CCt (1.0-5.6 mg/kg, s.c.), and the effects of zaleplon and zolpidem were also antagonized by flumazenil (0.01-0.32 mg/kg, s.c.). Schild analyses supported the notion of a simple, competitive interaction between beta-CCt and midazolam (slope = -1.08; apparent pA(2) = 5.41) or zaleplon (slope = -1.57; apparent pA(2) = 5.49) and not between beta-CCt and zolpidem. Schild analyses also were consistent with a simple, competitive interaction between flumazenil and zaleplon (slope = -1.03; apparent pA(2) = 7.45) or zolpidem (slope = -1.11; apparent pA(2) = 7.63). These results suggest that the same BZ receptor subtype(s) mediate(s) the effects of midazolam, zolpidem, and zaleplon under these conditions and that selective binding of BZ ligands does not necessarily confer selective effects in vivo.

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.