Comparative kinetics and dynamics of zaleplon, zolpidem, and placebo

Manipulation of REM sleep via orexin and GABAA receptor modulators differentially affects fear extinction in mice: effect of stable versus disrupted circadian rhythm

Sleep disruption, and especially REM sleep disruption, is associated with fear inhibition impairment in animals and humans. The REM sleep-fear inhibition relationship raises concern for individuals with PTSD, whose sleep disturbance is commonly treated with hypnotics which disrupt and/or decrease REM sleep, such as benzodiazepines or 'Z-drugs'. Here, we examined the effects of the Z-drug zolpidem, a GABAA receptor positive allosteric modulator, as well as suvorexant, an orexin receptor antagonist (hypnotics which decrease and increase REM sleep, respectively) in the context of circadian disruption in murine models of fear inhibition-related processes (i.e., fear extinction and safety learning). Adult male C57Bl/6J mice completed fear and safety conditioning before undergoing shifts in the light-dark (LD) cycle or maintaining a consistent LD schedule. Fear extinction and recall of conditioned safety were thereafter tested daily. Immediately prior to onset of the light phase between testing sessions, mice were treated with zolpidem, suvorexant, or vehicle (methylcellulose). EEG/EMG analysis showed temporal distribution of REM sleep was misaligned during LD cycle-shifts, while REM sleep duration was preserved. Suvorexant increased REM sleep and improved fear extinction rate, relative to zolpidem, which decreased REM sleep. Survival analysis demonstrated LD shifted mice treated with suvorexant were faster to achieve complete extinction than vehicle and zolpidem-treated mice in the LD shifted condition. By contrast, retention of conditioned safety memory was not influenced by either treatment. This study thus provides preclinical evidence for the potential clinical utility of hypnotics which increase REM sleep for fear extinction after PTSD-relevant sleep disturbance.

Effects of zolpidem and zaleplon on cognitive performance after emergent morning awakenings at Tmax: a randomized placebo-controlled trial

STUDY OBJECTIVES

Prescription sleep aids are frequently used in the general population and even more frequently in spaceflight. To evaluate the risk to operational safety, a ground-based, double-blind, placebo-controlled study on the emergent awakening effects of zolpidem and zaleplon was conducted.

METHODS

N = 34 participants (age M = 42.1 ± 9.7; 25 males; 9 Astronauts, 7 Astronaut candidates, and 18 Flight Controllers) were investigated for three nights separated by M = 10 days. They were randomized to ingestion of one of the following at lights out: placebo, 10 mg zaleplon, and either 5 mg (N = 20) or 10 mg (N = 14) zolpidem. They were awakened abruptly by alarm at the expected PK,max (1 hr after lights out for zaleplon; 1.5 hr for placebo/zolpidem). Participants were required to turn off the alarm and perform a cognitive test battery twice, separated by a 20-30 min reading break. They then returned to sleep and were awakened to perform the same cognitive tasks at an average of 6.7 hr after drug ingestion.

RESULTS

Relative to placebo, the effects of 10 mg zaleplon and 5 mg zolpidem on cognitive performance were minor. In contrast, 10 mg zolpidem adversely affected cognitive throughput (p < 0.001), psychomotor vigilance (p < 0.001), working memory (p < 0.01), delayed word recall (p < 0.05), and subjective sleepiness (p < 0.01) at the first emergent awakening. At terminal awakening, neither cognitive performance nor subjective sleepiness was impaired after ingestion of zaleplon or zolpidem (5 mg and 10 mg) compared with placebo.

CONCLUSIONS

Presleep ingestion of sleep medications, especially 10 mg zolpidem, poses a risk for performance errors after emergent awakenings near the expected PK,max.

REGISTRATION

Optimize Astronaut Sleep Medication Efficacy and Individual Effects (clinicaltrials.gov ID NCT03526575).

Neural oscillations demonstrate that general anesthesia and sedative states are neurophysiologically distinct from sleep

General anesthesia is a man-made neurophysiological state comprised of unconsciousness, amnesia, analgesia, and immobility along with maintenance of physiological stability. Growing evidence suggests that anesthetic-induced neural oscillations are a primary mechanism of anesthetic action. Each anesthetic drug class produces distinct oscillatory dynamics that can be related to the circuit mechanisms of drug action. Sleep is a naturally occurring state of decreased arousal that is essential for normal health. Physiological measurements (electrooculogram, electromyogram) and neural oscillatory (electroencephalogram) dynamics are used to empirically characterize sleep into rapid eye movement sleep and the three stages of non-rapid eye movement sleep. In this review, we discuss the differences between anesthesia- and sleep-induced altered states from the perspective of neural oscillations.

Zaleplon for Insomnia

Objective:

To assess the effectiveness data of zaleplon.

Data Sources:

Primary and review articles were identified by MEDLINE (1985 to August 2000) and via secondary sources.

Study Selection and Data Extraction:

All of the articles identified from the data sources were evaluated, and all information deemed relevant was included in this review.

Data Synthesis:

Eight studies were identified. Two trials in a nonelderly population investigated the effectiveness of zaleplon and the incidence of withdrawal symptoms. Zaleplon's only significant effect on insomnia was to reduce sleep latency by six to 16 minutes. The tools used in the trials showed that stopping zaleplon after 14–28 days of therapy did not cause significant rebound events. Two recent studies that investigated the use of zaleplon in the elderly produced similar results, although one study showed that stopping zaleplon causes significant rebound events. Three studies determined whether zaleplon caused any hangover effects and concluded that there is a low potential for these effects in a nonelderly population. In healthy nonelderly volunteers, standard doses of zaleplon had no residual effects when taken as little as two hours before the subjects arose. One small-scale study indicated that the abuse potential of zaleplon is similar to that of benzodiazepines.

Conclusions:

Although zaleplon significantly reduces sleep latency, the effect does not appear to be highly clinically significant. Zaleplon's short half-life does appear to reduce the risk of hangover effects. Until further data become available, zaleplon should be considered to have the same abuse potential as benzodiazepines.

Risks and benefits of zolpidem use in Taiwan: a narrative review

Zolpidem is a non-benzodiazepine hypnotic drug commonly used for the treatment of insomnia. However, to date, extensive evidence has shown that zolpidem use is a factor associated with certain clinical conditions, not that it treats these conditions. The aim of this review is to summarize current published articles on the risks and benefits of zolpidem use.

Pharmacokinetic effects of simultaneous administration of single-dose gabapentin 500 mg and zolpidem tartrate 10 mg in healthy volunteers: a randomized, open-label, crossover trial

Objective

Gabapentin is being investigated as a potential treatment for occasional disturbed sleep. This study assessed the pharmacokinetics and tolerability of gabapentin 500 mg and the commonly prescribed sedative/hypnotic zolpidem tartrate 10 mg, administered separately and in combination.

Methods

Forty healthy participants (19 male, 21 female) were randomized into this three-period crossover study [mean (range) age 34.1 (18–45) years, weight 68.3 (51.4–92.7) kg; 60 % white]. Participants were dosed with gabapentin alone (n = 39), zolpidem tartrate alone (n = 38), and the combination (gabapentin + zolpidem) (n = 38) over three treatment periods, which were separated by ≥7 days. Blood samples were collected pre-dose and 0.5, 1, 1.5, 2, 3, 4, 6, 8, 10, 12, 18, 24 and 36 h post-dose. Plasma concentrations of each drug were assayed using validated methods. Pharmacokinetic parameters were estimated from plasma concentration–time data using standard non-compartmental methods.

Results

For gabapentin + zolpidem combination versus gabapentin alone, mean pharmacokinetic parameters were peak plasma concentration (C_max) 4.61 versus 4.72 µg/mL, time to C_max (t_max) 4.63 versus 3.64 h and the area under plasma concentration–time curve extrapolated to infinity (AUC_0–∞) 53.4 versus 51.0 µg h/mL. For the combination versus zolpidem alone, mean pharmacokinetic parameters were C_max 154 versus 138 ng/mL, t_max 1.45 versus 1.84 h and AUC_0–∞ 912 versus 854 ng h/mL. The 90 % confidence intervals for C_max (rate of absorption) and AUC_0–∞ (extent of absorption) comparing the combination versus single drug administration fell within the 80–125 % range accepted for bioequivalence. All treatments were well tolerated.

Conclusion

The pharmacokinetics of gabapentin 500 mg and zolpidem tartrate 10 mg are unaffected when both drugs are taken simultaneously, compared with each drug taken alone.

Non-Benzodiazepine Receptor Agonists for Insomnia

Because of proven efficacy, reduced side effects, and less concern about addiction, non-benzodiazepine receptor agonists (non-BzRA) have become the most commonly prescribed hypnotic agents to treat onset and maintenance insomnia. First-line treatment is cognitive-behavioral therapy. When pharmacologic treatment is indicated, non-BzRA are first-line agents for the short-term and long-term management of transient and chronic insomnia related to adjustment, psychophysiologic, primary, and secondary causation. In this article, the benefits and risks of non-BzRA are reviewed, and the selection of a hypnotic agent is defined, based on efficacy, pharmacologic profile, and adverse events.

Risk of falling and hypnotic drugs: retrospective study of inpatients

Background

Falls and related injuries remain a concern for patient safety in many hospitals and nursing care facilities. In particular, reports examining the relationship between accidents and drugs with a sedative effect have been increasing; however, the analysis of correlation between the background factors of fall accidents and the detailed therapeutic category of drugs is insufficient.

Objectives

Our objective was to estimate fall risk following the administration of hypnotics in inpatients within an acute hospital. We assessed the relationship between falls and hypnotic drugs compared with other medicines.

Study Design and Setting

An inpatient population-based study was carried out at Gunma University Hospital, where all inpatients admitted between 1 October and 31 December 2007 were included. Over a 3-month follow-up period, all reports of falling accidents from ward medical staff were investigated.

Results and Discussion

Falls occurred in 1.8 % of males and 1.3 % of females in the study population (n = 3,683). The mean age of patients who experienced falls (64.7 ± 19.5 years) was significantly higher than that of patients who did not (56.2 ± 20.2 years). Multivariate analysis revealed the following drugs as high-risk factors for falling: hypnotics (odds ratio [OR] 2.17, 95 % CI 1.44–3.28), antiepileptics (OR 5.06, 95 % CI 2.70–9.46), opioids (OR 3.91, 95 % CI 2.16–7.10), anti-Alzheimer’s (OR 5.74, 95 % CI 1.62–20.3), anti-Parkinson’s (OR 5.06, 95 % CI 1.58–16.24), antidiabetics (OR 3.08, 95 % CI 1.63–5.84), antihypertensives (OR 2.24, 95 % CI 1.41–3.56), and antiarrhythmics (OR 2.82, 95 % CI 1.36–5.86). Multivariate logistic regression analysis of hypnotics, brotizolam, zopiclone, and estazolam revealed a significant association with an increased risk of inpatient falling accidents, while zolpidem, triazolam, flunitrazepam, and nitrazepam did not.

Conclusion

The present findings suggest that the risk of falling accidents in hospitals differs according to the type of hypnotic drug administered. The appropriate selection of hypnotic drugs, therefore, might be important for reducing the number of patient falls.

Electronic supplementary material

The online version of this article (doi:10.1007/s40268-013-0019-3) contains supplementary material, which is available to authorized users.

Residual effects of low-dose sublingual zolpidem on highway driving performance the morning after middle-of-the-night use

STUDY OBJECTIVE

To evaluate next-morning driving performance after middle-of-the-night use of zolpidem 3.5 mg in a buffered sublingual formulation (ZST).

DESIGN

Single-center, four-period, randomized, double-blind, placebo-controlled, crossover study.

SETTING

Maastricht University, The Netherlands.

PARTICIPANTS

Forty healthy volunteers (20 females).

INTERVENTIONS

Single dose of ZST administered in the middle of the night at 3 and 4 h before driving, zopiclone 7.5 mg at bedtime 9 h before driving, and placebo.

MEASUREMENTS

Performance in a 100-km standardized highway driving test in normal traffic measuring standard deviation of lateral position (SDLP) - an index of weaving. Drug-placebo changes in SDLP > 2.5 cm were considered to reflect clinically relevant driving impairment.

RESULT

For ZST, Max McNemar symmetry analyses showed that the proportion of drivers classified as impaired was increased 3 h after dosing (P < 0.012), but not 4 h after dosing. Mean increases in SDLP from placebo, although statistically significant, were small (1.46 cm [P < 0.0001] at 3 h and 0.83 cm [P = 0.0174] at 4 h). The morning after zopiclone, 45% of the drivers were classified as impaired with a mean increase in SDLP of 2.46 cm (P < 0.0001). There were no significant sex differences in effects of ZST and zopiclone.

CONCLUSION

Zolpidem 3.5 mg in a buffered sublingual formulation has a minimal risk of impairing driving performance in the morning ≥ 4 hours after middle-of-the night use. When taken 3 hours before driving, the drug may have impairing effects so caution should be exercised if medication is taken other than as indicated.

CLINICAL TRIAL INFORMATION

ClinicalTrials.gov Identifier: NCT01106859; Trial Name: Driving Performance After Middle of the Night Administration of 3.5 mg Zolpidem Tartrate Sublingual Tablet; http://clinicaltrials.gov/ct2/show/NCT01106859.

The effect of two benzodiazepine receptor agonist hypnotics on sleep-dependent memory consolidation

INTRODUCTION

Numerous studies have demonstrated that sleep promotes memory consolidation, but there is little research on the effect of hypnotics on sleep-dependent memory consolidation. We compared bedtime administration of zolpidem-ER 12.5 mg (6- to 8-h duration of action), middle-of-the-night administration of zaleplon 10 mg (3- to 4-h duration of action), and placebo to examine the effect of different durations of hypnotic drug exposure on memory consolidation during sleep.

METHODS

Twenty-two participants with no sleep complaints underwent 3 conditions in a counterbalanced crossover study: (1) zolpidem-ER 12.5 mg (bedtime dosing), (2) zaleplon 10 mg (middle-of-the-night dosing), and (3) placebo. Memory testing was conducted before and after an 8-h sleep period, using a word pair association task (WPT; declarative memory) and a finger-tapping task (FTT; procedural memory).

RESULTS

ANOVA revealed a significant condition effect for the WPT (p = 0.025) and a trend for the FTT (p = 0.067), which was significant when sex was added to the model (p = 0.014). Improvement in memory performance following sleep was lower with bedtime dosing of zolpidem-ER compared to placebo and middle-of-the-night dosing of zaleplon. There were no differences between placebo and zaleplon.

CONCLUSIONS

The results suggest that in some circumstances hypnotics may have the potential to reduce the degree of sleep-dependent memory consolidation and that drug-free sleep early in the night may ameliorate this effect.

Kinetic properties of "dual" orexin receptor antagonists at OX1R and OX2R orexin receptors

Orexin receptor antagonists represent attractive targets for the development of drugs for the treatment of insomnia. Both efficacy and safety are crucial in clinical settings and thorough investigations of pharmacokinetics and pharmacodynamics can predict contributing factors such as duration of action and undesirable effects. To this end, we studied the interactions between various “dual” orexin receptor antagonists and the orexin receptors, OX₁R and OX₂R, over time using saturation and competition radioligand binding with [³H]-BBAC ((S)-N-([1,1′-biphenyl]-2-yl)-1-(2-((1-methyl-1H-benzo[d]imidazol-2-yl)thio)acetyl)pyrrolidine-2-carboxamide). In addition, the kinetics of these compounds were investigated in cells expressing human, mouse and rat OX₁R and OX₂R using FLIPR® assays for calcium accumulation. We demonstrate that almorexant reaches equilibrium very slowly at OX₂R, whereas SB-649868, suvorexant, and filorexant may take hours to reach steady state at both orexin receptors. By contrast, compounds such as BBAC or the selective OX₂R antagonist IPSU ((2-((1H-Indol-3-yl)methyl)-9-(4-methoxypyrimidin-2-yl)-2,9-diazaspiro[5.5]undecan-1-one) bind rapidly and reach equilibrium very quickly in binding and/or functional assays. Overall, the “dual” antagonists tested here tend to be rather unselective under non-equilibrium conditions and reach equilibrium very slowly. Once equilibrium is reached, each ligand demonstrates a selectivity profile that is however, distinct from the non-equilibrium condition. The slow kinetics of the “dual” antagonists tested suggest that in vitro receptor occupancy may be longer lasting than would be predicted. This raises questions as to whether pharmacokinetic studies measuring plasma or brain levels of these antagonists are accurate reflections of receptor occupancy in vivo.

Gender differences in pharmacokinetics and pharmacodynamics of zolpidem following sublingual administration

The effect of dose and gender on the pharmacokinetics (PK) and pharmacodynamics (PD) of zolpidem after administration of a buffered zolpidem sublingual tablet (ZST; Intermezzo®, Purdue Pharma L.P., Stamford, CT, USA) was evaluated in healthy non-elderly male and female volunteers. Subjects received a single morning dose of ZST (1.0, 1.75, and 3.5 mg) or placebo in a four-way crossover study. In male and female subjects zolpidem PK were linear, with area under the curve (AUC) proportional to dose, and apparent oral clearance and elimination half-life independent of dose. However, AUC averaged 40% to 50% higher in females than in males receiving the same dose. The gender effect was incompletely explained by body weight. In females, ZST produced PD changes consistent with benzodiazepine agonist effects, particularly at the 3.5-mg dose. For several PD variables, PD effects were significantly related to plasma zolpidem concentrations when data were aggregated across subjects. However, there was variability in response among individuals. In males, PD effects of zolpidem seldom differed from placebo regardless of plasma concentration. The findings confirm that zolpidem clearance is lower in females than in males. PD effects of zolpidem from ZST are greater in female subjects, due to a combination of higher plasma concentrations and greater intrinsic sensitivity.

Dynamics and Kinetics of a Modified-Release Formulation of Zolpidem: Comparison With Immediate-Release Standard Zolpidem and Placebo

Modified-release (MR) zolpidem was developed to maintain effective plasma concentrations during the 3- to 6-hour post-dosage interval, corresponding to the middle portion of the typical sleep interval. Modified-release zolpidem (12.5 mg), standard immediate-release (IR) zolpidem (10 mg), and placebo were compared in a double-blind, single-dose, 3-way crossover daytime study of healthy volunteers (n = 70 completers). Effect areas for electroencephalographic beta amplitude during 0 to 8 hours and 3 to 6 hours after dosage were greater for MR compared to IR (P < .001). The digit-symbol substitution test and sedation rating scales behaved similarly. MR and IR did not differ in effects at 8 hours post-dosage nor in halflife or clearance. Time of peak plasma concentration (tmax) was significantly longer for MR (2.4 vs 2.0 hours, P < .004), and dose-normalized peak plasma concentration (Cmax) was lower (12.2 vs 14.0 ng/mL/mg, P < .001). MR zolpidem also had greater area under the plasma concentration curve (AUC) during the 3- to 6-hour interval (P < .001). Thus, MR zolpidem produces sustained plasma levels compared to IR, with resulting enhancement of pharmacodynamic effects in the 3- to 6-hour post-dosage interval.

The pharmacokinetics and pharmacodynamics of zaleplon delivered as a thermally generated aerosol in a single breath to volunteers

Pharmacokinetics, pharmacodynamics, safety, and tolerability of inhaled zaleplon were assessed in healthy volunteers. Forty participants received 0.5, 1, 2, or 4 mg zaleplon or placebo as a thermally generated aerosol in a randomized, double-blind, parallel-group, dose escalation study. Blood was collected up to 24 hours after dosing, and sedation was assessed up to 8 hours. Following inhalation, the observed median time to maximum plasma concentrations (25%, 75%) was 1.89 (1.45, 3.08) minutes and the mean (SD) elimination half-life was 1.24 (0.24) hours. The equilibration half-life for sedation (t(1/2) k(e0) ) was 1.16 (0.62, 2.17) minutes. The zaleplon AUC was dose proportional across doses, with a slope (90% confidence interval) of log-AUC versus log-dose of 0.92 (0.82, 1.02). No clinically significant changes were noted in laboratory values, vital signs, or spirometry. The most common adverse events were dizziness, somnolence, euphoria, headache, and visual disturbance. Zaleplon inhalation represents a safe, well-tolerated means of rapidly achieving effective plasma concentrations.

A systematic review of amnestic and non-amnestic mild cognitive impairment induced by anticholinergic, antihistamine, GABAergic and opioid drugs

BACKGROUND

Mild cognitive deficits are experienced by 18% of community-dwelling older adults, many of whom do not progress to dementia. The effect of commonly used medication on subtle impairments in cognitive function may be under-recognized.

OBJECTIVE

The aim of the review was to examine the evidence attributing amnestic or non-amnestic cognitive impairment to the use of medication with anticholinergic, antihistamine, GABAergic or opioid effects.

METHODS

MEDLINE and EMBASE were searched for randomized, double-blind, placebo-controlled trials of adults without underlying central nervous system disorders who underwent detailed neuropsychological testing prior to and after oral administration of drugs affecting cholinergic, histaminergic, GABAergic or opioid receptor pathways. Seventy-eight studies were identified, reporting 162 trials testing medication from the four targeted drug classes. Two investigators independently appraised study quality and extracted relevant data on the occurrence of amnestic, non-amnestic or combined cognitive deficits induced by each drug class. Only trials using validated neuropsychological tests were included. Quality of the evidence for each drug class was assessed based on consistency of results across trials and the presence of a dose-response gradient.

RESULTS

In studies of short-, intermediate- and long-acting benzodiazepine drugs (n = 68 trials), these drugs consistently induced both amnestic and non-amnestic cognitive impairments, with evidence of a dose-response relationship. H(1)-antihistamine agents (n = 12) and tricyclic antidepressants (n = 15) induced non-amnestic deficits in attention and information processing. Non-benzodiazepine derivatives (n = 29) also produced combined deficits, but less consistently than benzodiazepine drugs. The evidence was inconclusive for the type of cognitive impairment induced by different bladder relaxant antimuscarinics (n = 9) as well as for narcotic agents (n = 5) and antipsychotics (n = 5). Among healthy volunteers >60 years of age, low doses of commonly used medications such as lorazepam 0.5 mg, oxybutynin immediate release 5 mg and oxycodone 10 mg produced combined deficits.

CONCLUSION

Non-amnestic mild cognitive deficits are consistently induced by first-generation antihistamines and tricyclic antidepressants, while benzodiazepines provoke combined amnestic and non-amnestic impairments. Risk-benefit considerations should be discussed with patients in order to enable an informed choice about drug discontinuation or substitution to potentially reverse cognitive adverse effects.

Hydralazine as a selective probe inactivator of aldehyde oxidase in human hepatocytes: estimation of the contribution of aldehyde oxidase to metabolic clearance

Aldehyde oxidase (AO) metabolism could lead to significant underestimation of clearance in prediction of human pharmacokinetics as well as unanticipated exposure to AO-generated metabolites, if not accounted for early in drug research. We report a method using cryopreserved human hepatocytes and the time-dependent AO inhibitor hydralazine (K(I) = 83 ± 27 μM, k(inact) = 0.063 ± 0.007 min(-1)), which estimates the contribution of AO metabolism relative to total hepatic clearance. Using zaleplon as a probe substrate and simultaneously monitoring the AO-catalyzed formation of oxozaleplon and the CYP3A-catalyzed formation of desethyzaleplon in the presence of a range of hydralazine concentrations, it was determined that >90% inhibition of the AO activity with minimal effect on the CYP3A activity could be achieved with 25 to 50 μM hydralazine. This method was used to estimate the fraction metabolized due to AO [f(m(AO))] for six compounds with clearance attributed to AO along with four other drugs not metabolized by AO. The f(m(AO)) values for the AO substrates ranged between 0.49 and 0.83. Differences in estimated f(m(AO)) between two batches of pooled human hepatocytes suggest that sensitivity to hydralazine varies slightly with hepatocyte preparations. Substrates with a CYP2D6 contribution to clearance were affected by hydralazine to a minor extent, because of weak inhibition of this enzyme. Overall, these findings demonstrate that hydralazine, at a concentration of 25 to 50 μM, can be used in human hepatocyte incubations to estimate the contribution of AO to the hepatic clearance of drugs and other compounds.

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.

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.

Modeling sleep data for a new drug in development using markov mixed-effects models

PURPOSE

To characterize the time-course of sleep in insomnia patients as well as placebo and concentration-effect relationships of two hypnotic compounds, PD 0200390 and zolpidem, using an accelerated model-building strategy based on mixed-effects Markov models.

METHODS

Data were obtained in a phase II study with the drugs. Sleep stages were recorded during eight hours of sleep for two nights per treatment for the five treatments. First-order Markov models were developed for one transition at a time in a sequential manner; first a baseline model, followed by placebo and lastly the drug models. To accelerate the process, predefined models were selected based on a priori knowledge of sleep, including inter-subject and inter-occasion variability.

RESULTS

Baseline sleep was described using piece-wise linear models, depending on time of night and duration of sleep stage. Placebo affected light sleep stages; drugs also affected slow-wave sleep. Administering PD 0200390 30 min earlier than standard dosing was shown through simulations to reduce latency to persistent sleep by 40%.

CONCLUSION

The proposed accelerated model-building strategy resulted in a model well describing sleep patterns of insomnia patients with and without treatments.

Zolpidem and zopiclone impair similarly monotonous driving performance after a single nighttime intake in aged subjects

RATIONALE

Although hypnotics are primarily used by older people, the residual effects the morning after a single nighttime intake of the two most commonly prescribed hypnotics, zolpidem (Zp) and zopiclone (Zc), on older middle-aged drivers have not been evaluated and compared.

METHODS

Sixteen healthy subjects, 55 to 65 years of age, participated in this double-blind, balanced, cross-over study. Zc (7.5 mg), Zp (10 mg) and flunitrazepam (Fln) (1 mg) or a placebo was administered at each subject's home at 11.00 pm. The next morning, at 9.00 am, the subjects had to drive in a simulated monotonous driving environment for 1 h. During each morning session, two blood samples were collected, and subjective feelings of alertness were completed three times.

RESULTS

In comparison to placebo, Zp and Zc equivalently and significantly impaired the standard deviation of lateral position, the standard deviation of speed and the number of road exits. Detectable blood concentrations were found with Zp in 11 subjects at 8.30 am and at 1.30 pm. The subjective alertness factor was significantly impaired with Zp.

CONCLUSIONS

This is the first study revealing residual effects of Zp on driving performance in ageing drivers which are similar to that of Zc. Studying the effects of medication in different age ranges appears useful to complete the studies on behavioural-pharmacological effects of medication. To reduce the incidence of driving accidents due to prescription drugs, patients should be warned at the time of treatment initiation that they should avoid driving.

Drug interaction between St John's wort and zolpidem in healthy subjects

WHAT IS KNOWN AND OBJECTIVE

St John's wort (SJW, Hypericum perforatum) is one of the most commonly used herbal antidepressants for treatment of mild to moderate depression. SJW enhances CYP3A4 activity and alters the pharmacokinetics of CYP3A4 substrates. This study investigated the effect of SJW on the pharmacokinetics of zolpidem in healthy subjects.

METHODS

A controlled, open-label, non-randomized, fixed-dose schedule design was used. Fourteen healthy male subjects received a single 10 mg oral dose of zolpidem followed by SJW administration (300 mg orally, three times a day) for 14 days; the last dose of SJW was coadministered with a single dose of zolpidem. Blood samples were obtained over a 24-h period after zolpidem administration. Pharmacokinetic data for zolpidem alone and in combination with SJW were analysed by high-performance liquid chromatography.

RESULTS

After repeated administration of SJW, the mean values of AUC and C(max) for zolpidem significantly decreased (380.3 ± 181.4 vs. 265.4 ± 134.2 ng h/mL, P = 0.001; 83.1 ± 30.1 vs. 55.1 ± 24.8 ng/mL, P = 0.000 respectively) and the mean value of CL/F for zolpidem significantly increased (38.4 ± 31.5 vs. 56.9 ± 57.2 mL/min, P = 0.040). However, in three subjects, the AUC showed a small increase after SJW treatment.

WHAT IS NEW AND CONCLUSION

The effect of SJW on the pharmacokinetics of zolpidem has not previously been reported. Repeated administration of SJW decreases the plasma concentration of zolpidem, probably by enhancing CYP3A4 activity. Given the wide inter-subject variability observed, for personalized medicine, advice on the use of the combination should be individualized, based on the circumstances of the patient.

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.

The sedating antidepressant trazodone impairs sleep-dependent cortical plasticity

BACKGROUND

Recent findings indicate that certain classes of hypnotics that target GABA(A) receptors impair sleep-dependent brain plasticity. However, the effects of hypnotics acting at monoamine receptors (e.g., the antidepressant trazodone) on this process are unknown. We therefore assessed the effects of commonly-prescribed medications for the treatment of insomnia (trazodone and the non-benzodiazepine GABA(A) receptor agonists zaleplon and eszopiclone) in a canonical model of sleep-dependent, in vivo synaptic plasticity in the primary visual cortex (V1) known as ocular dominance plasticity.

METHODOLOGY/PRINCIPAL FINDINGS

After a 6-h baseline period of sleep/wake polysomnographic recording, cats underwent 6 h of continuous waking combined with monocular deprivation (MD) to trigger synaptic remodeling. Cats subsequently received an i.p. injection of either vehicle, trazodone (10 mg/kg), zaleplon (10 mg/kg), or eszopiclone (1-10 mg/kg), and were allowed an 8-h period of post-MD sleep before ocular dominance plasticity was assessed. We found that while zaleplon and eszopiclone had profound effects on sleeping cortical electroencephalographic (EEG) activity, only trazodone (which did not alter EEG activity) significantly impaired sleep-dependent consolidation of ocular dominance plasticity. This was associated with deficits in both the normal depression of V1 neuronal responses to deprived-eye stimulation, and potentiation of responses to non-deprived eye stimulation, which accompany ocular dominance plasticity.

CONCLUSIONS/SIGNIFICANCE

Taken together, our data suggest that the monoamine receptors targeted by trazodone play an important role in sleep-dependent consolidation of synaptic plasticity. They also demonstrate that changes in sleep architecture are not necessarily reliable predictors of how hypnotics affect sleep-dependent neural functions.

Impairment related to blood drug concentrations of zopiclone and zolpidem compared to alcohol in apprehended drivers

BACKGROUND

About 3-7% of the adult population receives prescribed hypnotics. The benzodiazepine-like hypnotics, zopiclone and zolpidem, are the most commonly prescribed and may cause traffic-relevant impairment similar to that found for benzodiazepines. We investigated the relationship between blood zopiclone and zolpidem concentrations and driving impairment, as assessed by the clinical test for impairment. We compared these groups of drivers to a group suspected of alcohol-related impairment.

METHODS

Blood samples from suspected impaired drivers during 2000-2007, screened for approximately 25 possible impairing drugs with only one single drug detected, were studied in relation to the assessment of impairment. The 79 zopiclone positive drivers, the 43 zolpidem positive drivers, and the 3480 alcohol positive drivers were divided into groups depending on blood drug concentrations.

RESULTS/DISCUSSION

The proportion of drivers judged as impaired tended to increase the higher the blood zopiclone concentrations. Such a positive relationship was not found for zolpidem. For alcohol the proportion of impaired drivers was significantly related to blood alcohol concentrations (BACs). There were few drivers with low zopiclone or zolpidem concentrations included, which may have obscured any positive significant relationship. The percentage of impaired drivers among drivers with blood zopiclone concentrations above 130 microg/l roughly corresponded to the percentage of impaired drivers among drivers with BACs higher than 0.1%.

Hypnosedative-induced complex behaviours : incidence, mechanisms and management

A number of news items and case reports describing complex behaviours (e.g. sleep driving, sleep cooking, sleep eating, sleep conversations, sleep sex) associated with the use of hypnosedative medications have recently received considerable attention. Regulatory agencies examining these reports have subsequently issued warnings regarding the potential of hypnosedative agents to produce complex behaviours. Despite these warnings, little is known about the likelihood, presentation, treatment or prevention of hypnosedative-induced complex behaviours. The purpose of this review is to evaluate the published evidence regarding the clinical presentation, incidence, mechanism and management of sleep-related behaviours induced by nonbenzodiazepine receptor agonists (NBRAs).Review of the literature identified ten published case reports of NBRA-induced complex behaviours involving 17 unique patients. Fifteen of the 17 patients described in the case reports had taken zolpidem, one had taken zaleplon and one had taken zopiclone. The complex behaviours most commonly reported were sleep eating, sleepwalking with object manipulation, sleep conversations, sleep driving, sleep sex and sleep shopping. Elevated serum concentrations resulting from increased medication dose or drug-drug interactions appeared to play a role in some but not all cases. Sex, age, previous medication exposure and concomitant disease states were not consistently found to be related to the risk of experiencing a medication-induced complex behaviour.From a pharmacological standpoint, enhancement of GABA activity at GABAA receptors (particularly alpha1-GABAA receptors) is a possible mechanism for hypnosedative complex behaviours and amnesia. Evidence suggests that complex behaviour risk may increase with both dose and binding affinity at alpha1-GABAA receptors. The amnesia that accompanies complex behaviours is possibly due to inhibition of consolidation of short- to long-term memory, suggesting that the risk may extend to non-GABAergic hypnosedatives. While amnesia and GABA-related receptor actions are the most frequently discussed mechanisms for complex behaviours in the literature, they do not fully explain such behaviours, suggesting that other mechanisms and factors probably play a role.A number of potential strategies are available to manage or prevent hypnosedative-induced complex behaviours. These include lowering the dose of, or stopping, the offending hypnosedative, switching to a different hypnosedative, treating patients with other classes of medications, using nonpharmacological treatment strategies for patients with sleep disorders, examining drug regimens for potential drug interactions that may predispose patients to experiencing complex behaviours, administering hypnosedative medications appropriately and selecting patients more carefully for treatment in terms of their likelihood of experiencing medication adverse effects.

A compendium of placebo-controlled trials of the risks/benefits of pharmacological treatments for insomnia: the empirical basis for U.S. clinical practice

For many years practitioners have had limited data from double-blind, placebo-controlled studies to guide the types of decision-making needed to optimally manage patients with insomnia in clinical practice. However, in recent years there has been a great increase in insomnia research studies that address issues of clinical importance. This body of work represents an increasingly useful empirical basis for making clinical practice decisions. The purpose of this article is to compile the body of work on the pharmacological management of insomnia to make it available in as accessible form as possible for optimal application in clinical practice with the hopes that doing so will decrease the gap separating the available research and the clinical management of insomnia and, thereby, improve the care of the many individuals who suffer from this condition. The review of studies consists of the following sections: 1) basic pharmacology; 2) double-blind, placebo-controlled trials in adults with primary insomnia; 3) double-blind, placebo-controlled trials in elderly patients with primary insomnia; 4) adverse effects reported in placebo-controlled trials in elderly primary insomnia patients; 5) double-blind, placebo-controlled trials in adults and the elderly as a function of treatment duration; 6) double-blind, placebo-controlled trials of the treatment of comorbid insomnia. Issues related to the application of these data to clinical practice are discussed in the text.

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.

Abuse and dependence liability of benzodiazepine-type drugs: GABA(A) receptor modulation and beyond

Over the past several decades, benzodiazepines and the newer non-benzodiazepines have become the anxiolytic/hypnotics of choice over the more readily abused barbiturates. While all drugs from this class act at the GABA(A) receptor, benzodiazepine-type drugs offer the clear advantage of being safer and better tolerated. However, there is still potential for these drugs to be abused, and significant evidence exists to suggest that this is a growing problem. This review examines the behavioral determinants of the abuse and dependence liability of benzodiazepine-type drugs. Moreover, the pharmacological and putative biochemical basis of the abuse-related behavior is discussed.

Daytime pharmacodynamic and pharmacokinetic evaluation of low-dose sublingual transmucosal zolpidem hemitartrate

OBJECTIVES

Buffered low-dose sublingual transmucosal zolpidem lozenge hemitartrate (ST zolpidem) is being developed for the treatment of middle-of-the-night insomnia. The objective of this double-blind placebo-controlled cross-over study (n = 24) was to evaluate the pharmacokinetics (PK) and daytime-sedative profile of 1.0, 1.75, and 3.5 mg dose of the formulation.

METHODS

Daytime sedation was measured pre-dose and up to 5 h post-dose objectively by the Digit Symbol Substitution Test (DSST) and subjectively using the Visual Analog Scale (VAS). Blood samples for PK assessment was collected pre-dose and up to 12 h post-dose.

RESULTS

The 1.75 and 3.5 mg, but not the 1 mg, ST zolpidem produced significant sedation versus placebo within 20 min of dosing which lasted for up to 3 h. Zolpidem from the formulation was rapidly absorbed and reached maximum plasma concentrations within 38 min of dosing, however the half-life was independent of the dose and side effects were consistent with the known pharmacology of the drug.

CONCLUSIONS

ST zolpidem produced rapid, short duration of sedation and the effect was consistent with its PK profile. This novel low-dose formulation of zolpidem may provide clinicians and patients with a prn option for the management of sleep maintenance insomnia.

Use of non-benzodiazepine hypnotics in the elderly: are all agents the same?

Sleep disorders, especially insomnia, are common in older adults. These disorders are frequently treated using non-benzodiazepine hypnotics. Nonetheless, there is a relative lack of data regarding the use of these agents in the elderly, and whether any of these medications is superior to any other in the class when used in the elderly is also unclear. In this article, we review, by way of the published literature, the pharmacodynamics, pharmacokinetics, drug interactions, efficacy and safety of zolpidem, zaleplon, zopiclone, eszopiclone and ramelteon in the elderly. Special emphasis is placed on identifying relevant differences between these medications when used in older adults with insomnia. Based primarily on data from placebo-controlled trials, the non-benzodiazepines reviewed were found to be most effective at improving sleep latency and sleep quality, and least effective at enhancing total sleep time. The efficacy of ramelteon was limited to improving sleep latency, while all other agents, especially at higher doses, were found to produce improvement in both sleep latency and some improvement in total sleep time. All of the medications were found to be well tolerated in the elderly. From pharmacokinetic and drug-drug interaction perspectives, zaleplon and ramelteon offer the advantage of not being primarily metabolised via the cytochrome P450 3A4 isoenzyme. In conclusion, based on relatively limited data, zopiclone, zolpidem, zaleplon, eszopiclone and ramelteon represent modestly effective and generally well tolerated treatments for insomnia in older adults. While some actual and potential differences exist among these medications, more comparative trials are needed.

Effects of chromosomal variations on pharmacokinetic activity of zolpidem in healthy volunteers: An array-based comparative genomic hybridization study

Zolpidem has been known as a very safe and effective hypnotic drug used to treat a variety of patients with insomnia. Even though the same dose of the medicine is administered to each patient, the blood level of zolpidem and the time required to obtain peak concentration are not consistent among different people. We evaluated the relationship between the peak concentrations of zolpidem and chromosomal imbalances using a high-resolution genome-wide array-based comparative genomic hybridization (CGH) in 16 healthy volunteers in order to detect the genetic factors underlying the variations. The present study showed that chromosomal losses were detected in the 4q35.2, 9p13.1 and 9p12 regions, and those gains were indicated in the 2p14, 11q13.4 and 15q11.2 regions. The abnormal regions were confirmed by fluorescence in situ hybridization (FISH) and real-time PCR. It is suggested that array-CGH analysis may be used as a measure for pharmacogenomic applications in the patients with insomnia and for further exploration of candidate genomic regions implicated in sleep disturbances.

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.

Age and gender effects on the pharmacokinetics and pharmacodynamics of ramelteon, a hypnotic agent acting via melatonin receptors MT1 and MT2

Effects of age and gender on the pharmacokinetics and pharmacodynamics of ramelteon, a hypnotic acting via binding to melatonin MT(1) and MT(2) receptors, were evaluated in healthy young (18-34 years) and elderly (63-79 years) volunteers. Part 1 evaluated the pharmacokinetics of open-label oral ramelteon, 16 mg. Part 2 was a double-blind, randomized, 2-trial crossover pharmacodynamic study of 16-mg ramelteon and matching placebo. Ramelteon clearance was significantly reduced in elderly vs young volunteers (384 vs 883 mL/min/kg, P<.01) and half-life significantly increased (1.9 vs 1.3 h, P<.001). Gender did not significantly influence clearance or half-life. Ramelteon was extensively transformed to its hydroxylated M-II metabolite, with serum AUC values averaging about 30 times those of the parent drug. Compared to placebo, ramelteon increased self- and observer-rated sedation, but age and gender did not influence the magnitude of the ramelteon-placebo difference. Ramelteon did not significantly impair digit-symbol substitution test performance or impair information acquisition and recall. Thus, the reduced clearance and higher serum levels of ramelteon in elderly subjects were not associated with enhanced pharmacodynamic effects. The usually recommended clinical dose of ramelteon (8 mg) does not require modification based on age or gender.

Prediction of in vivo drug clearance from in vitro data. I: impact of inter-individual variability

The Simcyp Population-Based ADME Simulator was used to predict median drug clearances and their associated variance from in vitro data. Fifteen drugs satisfied the entry criteria for the study and the relevant information (in vitro metabolism data and in vivo human clearance values) were collated from the literature. Predicted values of median clearances fell within 2-fold of observed values for 73% of the drugs (oral route) and 78% of the drugs (intravenous route) when microsomal binding was disregarded, and for 93% (oral) and 100% (intravenous) when it was considered. Irrespective of whether microsomal binding was considered, the predicted fold variability fell within 2-fold of the observed variability for 80% (oral) and 67% (intravenous) of the drugs.

Effect of voriconazole on the pharmacokinetics and pharmacodynamics of zolpidem in healthy subjects

AIMS

To assess the effect of voriconazole on the pharmacokinetics and pharmacodynamics of zolpidem.

METHODS

In a randomized cross-over study with two phases, 10 healthy subjects ingested 10 mg of zolpidem with or without oral voriconazole pretreatment. The concentrations of zolpidem were measured in plasma up to 24 h and pharmacodynamic variables were monitored for 12 h.

RESULTS

Voriconazole increased the peak plasma concentration of zolpidem by 1.23-fold [P < 0.05; 90% confidence interval (CI) 1.05, 1.45] and the area under the plasma zolpidem concentration-time curve by 1.48-fold (P < 0.001; 90% CI 1.29, 1.74). The time to peak plasma zolpidem concentration was unchanged by voriconazole but the half-life was prolonged from 3.2 to 4.1 h (P < 0.01; 95% CI on the difference 0.27, 1.45). The pharmacodynamics of zolpidem were unaffected by voriconazole.

CONCLUSION

Voriconazole caused a moderate increase in exposure to zolpidem in healthy young subjects but no clear pharmacodynamic changes were observed between the groups.

A double-blind, placebo- and flurazepam-controlled investigation of the residual psychomotor and cognitive effects of modified release zolpidem in young healthy volunteers

Short-acting hypnotic drugs, such as zolpidem, have minimal residual effects but may not provide optimal efficacy throughout the night for all insomnia patients. A modified-release formulation of zolpidem, zolpidem-MR, has been developed to overcome this limitation. This was a phase I, double-blind, 3-way crossover, placebo-controlled study to investigate the residual psychomotor and cognitive effects of a single oral dose of zolpidem-MR 12.5 mg in 18 healthy young adults. Flurazepam 30 mg was used as a positive control. No comparison with standard immediate-release zolpidem was made. Five neuropsychological tests and 2 subjective tests were performed 8 hours after dosing. The safety of zolpidem-MR was also investigated. Performance on the Critical Flicker Fusion Frequency test, Choice Reaction Time, Immediate and Delayed Word Recall, and the Compensatory Tracking Task was significantly impaired by flurazepam but not by zolpidem-MR (with the exception of the Compensatory Tracking Task) or placebo. No significant effects were observed on the Digit Symbol Substitution Test. The Leeds Sleep Evaluation Questionnaire showed that both drugs improved the ease of getting to sleep and perceived quality of sleep, whereas only flurazepam significantly impaired the ease of awakening. Neither drug scored significantly better than placebo on the Bond and Lader contentedness scale, but both induced a significant difference in calmness; only flurazepam significantly reduced alertness. The safety profile of zolpidem-MR was comparable to placebo. In conclusion, the study showed the good tolerance of zolpidem-MR in terms of residual neuropsychological effects as well as a beneficial effect on sleep quality in young healthy adults.

Kinetics and dynamics of intravenous adinazolam, N-desmethyl adinazolam, and alprazolam in healthy volunteers

The pharmacokinetics and pharmacodynamics of adinazolam mesylate (10 mg), N-desmethyl adinazolam mesylate (NDMAD, 10 mg), and alprazolam (1 mg) were investigated in 9 healthy male subjects in a randomized, blinded, single-dose, 4-way crossover study. All drugs were intravenously infused over 30 minutes. Plasma adinazolam, NDMAD, and alprazolam concentrations, electroencephalographic (EEG) activity in the beta (12-30 Hz) range, performance on the Digit Symbol Substitution Test (DSST), and subjective measures of mood and sedation were monitored for 12 to 24 hours. Mean pharmacokinetic parameters for adinazolam, NDMAD, and alprazolam, respectively, were as follows: volume of distribution (L), 106, 100, and 77; elimination half-life (hours), 2.9, 2.8, and 14.6; and clearance (mL/min), 444, 321, and 84. More than 80% of the total infused adinazolam dose was converted to systemically appearing NDMAD. All 3 benzodiazepine agonists significantly increased beta EEG activity, with alprazolam showing the strongest agonist activity and adinazolam showing the weakest activity. Alprazolam and NDMAD significantly decreased DSST performance, whereas adinazolam had no effect relative to placebo. Adinazolam, NDMAD, and alprazolam all produced significant observer-rated sedation. Plots of EEG effect versus plasma alprazolam concentration demonstrated counterclockwise hysteresis, consistent with an effect site delay. This was incorporated into a kinetic-dynamic model in which hypothetical effect site concentration was related to pharmacodynamic EEG effect via the sigmoid E(max) model, yielding an effect site equilibration half-life of 4.8 minutes. The exponential effect model described NDMAD pharmacokinetics and EEG pharmacodynamics. The relation of both alprazolam and NDMAD plasma concentrations to DSST performance could be described by a modified exponential model. Pharmacokinetic-dynamic modeling was not possible for adinazolam, as the data did not conform to any known concentration-effect model. Collectively, these results indicate that the benzodiazepine-like effects occurring after adinazolam administration are mediated by mainly NDMAD.

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.

Zolpidem and triazolam do not affect the nocturnal sleep-induced memory improvement

RATIONALE

It is widely accepted that sleep facilitates memory consolidation. Hypnotics (e.g., benzodiazepines), which reportedly increase sleep efficiency but also modify sleep architecture, could affect memory improvement that occurs during sleep.

OBJECTIVES

The present study examined the effects of single doses of two short half-life hypnotics, zolpidem and triazolam, on sleep-induced improvement of memory.

METHODS

Twenty-two healthy volunteers participated in this randomized, double-blind, crossover study. All subjects received a single oral dose of zolpidem (10 mg), triazolam (0.25 mg) or placebo at 9 P.M.: and slept for 7.5+/-0.2 h. The effect of sleep on memory was investigated by comparing the performance of this group of volunteers with a group of 21 subjects in wakefulness condition. Declarative memory was evaluated by using a free-recall test of ten standard word and seven nonword lists. Subjects memorized the word and nonword lists 1 h before dosing and they were asked to recall the memorized lists 10 h after dosing. Digit symbol substitution test (DSST) and forward and backward digit tests were also given 1 h before and 10 h after dosing.

RESULTS

Subjects who slept remembered more nonwords than those in wakefulness condition, but they did not recall significantly more standard words. Neither zolpidem nor triazolam affected the enhanced nonword recall observed after sleep. Finally, none of the hypnotics affected the improvement in the DSST performance of subjects who slept.

CONCLUSIONS

The hypnotics tested did not interfere with the nocturnal sleep-induced improvement of memory.