Pharmacokinetic profile of a new modified release formulation of zolpidem designed to improve sleep maintenance

Efficacy and Safety of Transitioning to Lemborexant from Z-drug, Suvorexant, and Ramelteon in Japanese Insomnia Patients: An Open-label, Multicenter Study

INTRODUCTION

For patients with chronic insomnia, conventional therapy may not always provide satisfactory efficacy and safety. Thus, switching to an alternative therapeutic agent can be explored. However, there is a lack of prospective studies evaluating the effectiveness of such changes. This prospective, non-randomized, open-label, interventional, multicenter study assessed whether Japanese patients with chronic insomnia dissatisfied with treatment could transition directly to lemborexant (LEM) from four cohorts-non-benzodiazepine sedative-hypnotic (zolpidem, zopiclone, or eszopiclone) monotherapy, dual orexin receptor antagonist (suvorexant) monotherapy, suvorexant + benzodiazepine receptor agonists (BZRAs), and melatonin receptor agonist (ramelteon) combination. We evaluated whether transitioning to LEM improved patient satisfaction based on efficacy and safety.

METHODS

The primary endpoint was the proportion of successful transitions to LEM at 2 weeks (titration phase end), defined as the proportion of patients on LEM by the end of the 2-week titration phase who were willing to continue on LEM during the maintenance phase (Weeks 2-14). Patient satisfaction and safety (the incidence of treatment-emergent adverse events [TEAEs]) were assessed at 14 weeks (end of titration and maintenance phases).

RESULTS

Among the 90 patients enrolled, 95.6% (95% confidence interval: 89.0-98.8%) successfully transitioned to LEM at 2 weeks. The proportions of patients who successfully continued on LEM were 97.8% and 82.2% at the end of the titration and maintenance phases (Weeks 2 and 14), respectively. The overall incidence of TEAEs was 47.8%; no serious TEAEs occurred. In all cohorts, the proportions of patients with positive responses were higher than the proportions with negative responses on the three scales of the Patient Global Impression-Insomnia version. During the maintenance phase, Insomnia Severity Index scores generally improved at Weeks 2, 6, and 14 of LEM transition.

CONCLUSIONS

Direct transition to LEM may be a valid treatment option for patients with insomnia who are dissatisfied with current treatment.

TRIAL REGISTRATION

ClinicalTrials.gov identifier, NCT04742699.

In-vitro–in-silico investigation of the negative food effect of zolpidem when administered as immediate-release tablets

Objectives

The main objective of the present work was to combine in-vitro and in-silico tools to better understand the in-vivo behavior of the immediate release (IR) formulation of zolpidem in the fasted and fed states.

Methods

The dissolution of zolpidem was evaluated using biorelevant media simulating the gastric and intestinal environment in the fasted and fed states. Additionally, the influence of high viscosity and high fat content on the release of zolpidem under fed state conditions was investigated. The in-vitro results were combined with a physiologically based pharmacokinetic (PBPK) model constructed with Simcyp® to simulate the zolpidem pharmacokinetic profile in both prandial states.

Key findings

In vitro biorelevant dissolution experiments representing the fasted and fed states, combinedwith PBPKmodelling, were able to simulate the plasma profiles from the clinical food effect studies well. Experiments reflecting the pH and fat content of themeal led to a good prediction of the zolpidem plasma profile in the fed state, whereas increasing the viscosity of the gastricmedia led to an under-prediction.

Conclusions

This work demonstrates that the combination of biorelevant dissolution testing and PBPK modelling is very useful for understanding the in-vivo behavior of zolpidem in the fasted and fed states. This approach could be implemented in the development of other drugs exhibiting negative food effects, saving resources and bringing new drug products to the market faster.

LC-MS-MS with Post-Column Reagent Addition for the Determination of Zolpidem and its Metabolite Zolpidem Phenyl-4-carboxylic Acid in Oral Fluid after a Single Dose

A rapid, selective and sensitive LC-MS-MS method with a post-column addition of acetonitrile was developed and fully validated for the quantitative determination of zolpidem and its major metabolite, zolpidem phenyl-4-carboxylic acid (ZPCA), in oral fluid. Preliminary sample treatment was limited to a simple dilution of 1 mL oral fluid specimen aliquots with methanol. Chromatography was performed on a Capcell Pak C18 MGII column (250 × 2.0 mm, 5 μm i.d., Shiseido, Tokyo, Japan) with isocratic elution using a water-acetonitrile mobile phase with 0.1% formic acid, 5% acetonitrile and 20 mM ammonium acetate in an aqueous phase at a flow rate of 0.4 mL/min. Acetonitrile was added post-column at a flow rate of 0.4 mL/min to enhance ionization of the analytes in the MS source. Detection was carried out on a QTrapTM 6500 mass spectrometer in positive ionization mode. Good linearities were generated over the range of 0.05-200 ng/mL for zolpidem and 0.1-200 ng/mL for ZPCA. Limit of detection for zolpidem and ZPCA were 0.01 ng/mL and 0.05 ng/mL, respectively, whereas LLOQs were 0.05 ng/mL and 0.1 ng/mL, respectively. This method meets the required criteria for bioanalytical analyses to be used for clinical and forensic purposes. Application of this method was demonstrated by testing authentic samples collected after a single oral dose to obtain insights into the general detectability and detection windows of zolpidem and ZPCA in oral fluid.

Determination of zolpidem in human plasma by liquid chromatography-tandem mass spectrometry for clinical application

Zolpidem (ZPD) is widely described for the short-term treatment of insomnia. We have developed and validated a simple and rapid liquid chromatography analytical method using tandem mass spectrometry (LC-MS/MS) for the quantification of ZPD in human plasma. Using dibucaine as an internal standard (IS), the analyte was extracted with methyl t-butyl ether (MTBE). Chromatographic separation of ZPD was performed on a reversed-phase Luna C18 column (50 mm × 2.0 mm i.d., 5 μm particles) with a mobile phase of 10mM ammonium formate buffer (pH 3.0)-methanol (15:85, v/v) at a flow rate of 250 μm/min. The total run-time was 2.5 min and the retention times of ZPD and IS were 0.66 and 0.74 min, respectively. The mass-to-charge transition monitored for quantification of ZPD and IS was 308.2→235.2 and 344.0→271.0, respectively. The lower limit of quantification (LLOQ) using 100 μL of human plasma was 0.05 ng/mL and the calibration curves were linear over a range of 0.05-200 ng/mL (r(2)>0.9964). The mean accuracy and precision for intra- and inter-run validation of ZPD were within acceptable limits. In the present LC-MS/MS method, we showed improved sensitivity for quantification of the ZPD in human plasma using lower volume of plasma compared with previously described analytical methods for ZPD. This validated method was successfully applied to a pharmacokinetic study in humans.

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.

Drug treatment of primary insomnia: a meta-analysis of polysomnographic randomized controlled trials

CONTEXT

Although insomnia is a frequent health complaint that is often treated with drugs, little is known about differences in treatment efficacy of various drug classes on objective versus subjective outcome measures.

OBJECTIVE

Our aim was to compare treatment efficacy of classical benzodiazepines, benzodiazepine receptor agonists (zopiclone, zolpidem and zaleplon), antidepressants (including low-dose doxepin), neuropeptides, progesterone receptor antagonists, hormones, melatonin receptor agonists, antihistamines, antiepileptics, and narcotics addressing primary insomnia.

DATA SOURCES

We conducted a comprehensive literature search (up to 5 April 2013) using PubMed, Cochrane Clinical Trials, PQDT OPEN, OpenGREY, ISI Web of Knowledge, PsycINFO, PSYNDEX, and the WHO International Clinical Trials Registry Platform.

ELIGIBILITY CRITERIA

Only polysomnographic, parallel-group, randomized controlled drug trials were included; eligibility was determined by two independent authors.

DATA SYNTHESIS

We used a random effects model, based on 31 studies reporting 80 treatment conditions, covering 3,820 participants.

RESULTS

Effect size estimates for the total sample of pooled drug classes suggest that there is a small-to-moderate, significant, and robust effect for objective outcomes (sleep onset latency g = -0.36, total sleep time g = 0.27) and subjective outcomes (sleep onset latency g = -0.24, total sleep time g = 0.21). Results indicate higher effect sizes for benzodiazepine receptor agonists and classical benzodiazepines compared with antidepressants (including low-dose doxepin) and for classical benzodiazepines compared with benzodiazepine receptor agonists. Benzodiazepine receptor agonists demonstrated higher effect sizes for objective outcomes.

LIMITATIONS

Data on drug safety were not analyzed.

CONCLUSIONS

Future studies should use objective and subjective assessment. Focusing on efficacy, clinicians should favor benzodiazepine receptor agonists and classical benzodiazepines over antidepressants (including low-dose doxepin) for primary insomnia treatment, but the additional consideration of different side effect profiles can lead to alternative treatment decisions.

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.

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.

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.

CYP3A4 and CYP2C19 genetic polymorphisms and zolpidem metabolism in the Chinese Han population: a pilot study

Zolpidem (ZPD) is an imidazopyridine hypnotic and little is known about the pharmacogenetics of ZPD. Our objective was to evaluate inter-individual genetic variation in conjunction with metabolic ratios of ZPD found in a toxicological analysis. Healthy individuals (n=300) were genotyped for CYP2D6, CYP2C19, CYP2C9, CYP3A4 and CYP1A2 by allele-specific primer extension followed by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS). Twenty-four Chinese volunteers were chosen and divided into the following four groups (n=6/group): group 1: CYP3A4*18 (wild-type, W), CYP2C19*2 (W); group 2: CYP3A4*18 (mutant, M), CYP2C19*2 (W); group 3: CYP3A4*18 (W), CYP2C19*2 (M); and group 4: CYP3A4*18 (M), CYP2C19*2 (M). ZPD and its major metabolites zolpidem 6-carboxylic acid (ZCA) and zolpidem phenyl-4-carboxylic acid (ZPCA) were determined after oral administration of ZPD (10mg), using an UPLC-MS/MS method. Positive correlations between CYP3A4 and CYP2C19 alleles and ZPD metabolism were found. The results of this study show that CYP3A4*18 increases CYP3A4 activity while CYP2C19*2 reduces CYP2C19 activity; the latter mutation is associated with the poor metabolism of ZPD in the Chinese Han population. The results also suggest that genetic factors play a major role in the metabolism of individual drugs with implications for both forensic science and clinical pharmacogenetics.

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.

Use of partial AUC to demonstrate bioequivalence of Zolpidem Tartrate Extended Release formulations

PURPOSE

FDA's bioequivalence recommendation for Zolpidem Tartrate Extended Release Tablets is the first to use partial AUC (pAUC) metrics for determining bioequivalence of modified-release dosage forms. Modeling and simulation studies were performed to aid in understanding the need for pAUC measures and also the proper pAUC truncation times.

METHODS

Deconvolution techniques, In Vitro/In Vivo Correlations, and the CAT (Compartmental Absorption and Transit) model were used to predict the PK profiles for zolpidem. Models were validated using in-house data submitted to the FDA. Using dissolution profiles expressed by the Weibull model as input for the CAT model, dissolution spaces were derived for simulated test formulations.

RESULTS

The AUC(0-1.5) parameter was indicative of IR characteristics of early exposure and effectively distinguished among formulations that produced different pharmacodynamic effects. The AUC(1.5-t) parameter ensured equivalence with respect to the sustained release phase of Ambien CR. The variability of AUC(0-1.5) is higher than other PK parameters, but is reasonable for use in an equivalence test.

CONCLUSIONS

In addition to the traditional PK parameters of AUCinf and Cmax, AUC(0-1.5) and AUC(1.5-t) are recommended to provide bioequivalence measures with respect to label indications for Ambien CR: onset of sleep and sleep maintenance.

Role of zolpidem in the management of insomnia

Insomnia is a common condition that affects one's ability to sleep comfortably and consequently to work effectively. Its etiology is multifactorial and involves plethora of risk factors. Consequences can vary from mild sleepiness to more sever psychiatric disturbances and ischemic stroke. Despite several diagnostic criteria it is poorly diagnosed and less often treated. Benzodiazepines formed the mainline therapy for many years till the advent of newer nonbenzodiazepine group of drugs including zolpidem. Zolpidem is an imidazo-pyridine compound that enhances the GABA(A) receptor function by interaction with Omega-1 receptor subtype. Its pharmacokinetic profile allows the patients to use it later in the night when having trouble falling asleep without any residual cognitive impairment the next morning. It has rapid onset of action, improves total sleep duration, and reduces night-time awakenings. Its adverse effect profile is satisfactory as it appears to have low addiction potential. This review will focus on the current role of zolpidem in the management of insomnia.

Desensitization of GABAergic receptors as a mechanism of zolpidem-induced somnambulism

Sleepwalking is a frequently reported side effect of zolpidem which is a short-acting hypnotic drug potentiating activity of GABA(A) receptors. Paradoxically, the most commonly used medications for somnambulism are benzodiazepines, especially clonazepam, which also potentiate activity of GABA(A) receptors. It is proposed that zolpidem-induced sleepwalking can be explained by the desensitization of GABAergic receptors located on serotonergic neurons. According to the proposed model, the delay between desensitization of GABA receptors and a compensatory decrease in serotonin release constitutes the time window for parasomnias. The occurrence of sleepwalking depends on individual differences in receptor desensitization, autoregulation of serotonin release and drug pharmacokinetics. The proposed mechanism of interaction between GABAergic and serotonergic systems can be also relevant for zolpidem abuse and zolpidem-induced hallucinations. It is therefore suggested that special care should be taken when zolpidem is used in patients taking at the same time selective serotonin reuptake inhibitors.

Searching for perfect sleep: the continuing evolution of GABAA receptor modulators as hypnotics

The non-benzodiazepine GABA(A) receptor modulators ('Z-drugs') - zaleplon, zolpidem, zopiclone and eszopiclone - have become the accepted treatments for insomnia where they are available. However, recent randomized, placebo-controlled trials suggest that, for these drugs, there may be particular efficacy and tolerability profiles and distinct clinical outcomes in specific patient populations. This is particularly apparent when hypnotic/ selective serotonin reuptake inhibitor co-therapy is used to treat patients with co-morbid insomnia and psychiatric disorders, as patient recovery appears to be accelerated and enhanced by some drugs but not others. Emerging evidence of why this should be the case is that these hypnotic drugs may differ significantly from each other in their pharmacodynamic and pharmacokinetic profiles. Functional selectivity for specific GABA(A) receptor subtypes may determine each drug's clinical attributes, while the pharmacokinetic characteristics of Z-drugs also determine to a large extent how they perform in the clinic. For example, activity at GABA(A) alpha 1 receptor subtypes may be associated with sedative effects, whereas activity at alpha 2 and alpha 3 receptor subtypes may be associated with anxiolytic and antidepressant effects. In summary, the distinct clinical outcomes of zaleplon, zolpidem, zopiclone and eszopiclone may be explained by each drug's unique GABA(A) receptor subunit selectivity and pharmacokinetic profile. Further investigation of GABA( A) receptor subtype effects would help to increase understanding of current hypnotic drug effects, while knowledge of each drug's specific binding profile should enable clinicians to tailor treatment to individual patient's needs.

Immediate- and controlled-release zolpidem ingestions reported to Texas poison centers

Zolpidem is available in immediate-release (IR) and controlled-release (CR) formulations. This investigation examined whether there were differences in zolpidem IR and CR ingestions reported to poison control centers. Zolpidem ingestions that did not involve coingestants reported to Texas poison control centers during 2005-2008 were identified. The ingestions were grouped by IR and CR formulations and compared with respect to demographic and clinical factors. There were 734 IR and 163 CR ingestions. The mean dose ingested was 92.9 mg and 104.6 mg, respectively. IR and CR cases were, respectively, 56.9% and 58.3% male, 54.6% and 49.7% age >19 years, 65.0% and 65.0% already at or en route to a health care facility when the poison control center was contacted, and 30.1% and 39.3% involved no effect. The most frequently reported adverse clinical effects were, for IR and CR, respectively, drowsiness (54.4% vs 42.3%), tachycardia (10.6% vs 11.7%), ataxia (6.3% vs 11.7%), slurred speech (6.3% vs 6.7%), vomiting (5.0% vs 5.5%) and hallucinations/delusions (4.9% vs 3.1%). The distribution of zolpidem IR and CR ingestions reported to Texas poison control centers were similar. However, zolpidem CR ingestions appeared less likely to result in drowsiness and hallucinations but more likely to result in ataxia.

Treatment options for insomnia--pharmacodynamics of zolpidem extended-release to benefit next-day performance

BACKGROUND

Insomnia can manifest as difficulty in falling asleep, in maintaining sleep throughout the night, or waking up too early, with symptoms often unpredictably changing over time. Pharmacologic options for insomnia treatment include prescription hypnotics, such as gamma-amino butyric acid-receptor agonists, sedating antidepressants, over-the-counter antihistamines, melatonin-receptor agonists, and alternative therapies. A concern with insomnia medications is the risk of next-day residual effects, which can impair memory and ability to perform certain tasks, such as driving, and may increase the risk of accidents and falls, especially in the elderly.

OBJECTIVES

To describe the impact of current insomnia treatments on next-day performance.

RESULTS

The longer-acting benzodiazepines are associated with next-day "hangover" effects and, as a result, have been largely replaced by agents in the nonbenzodiazepine class, which typically have shorter half-lives. The hypnotic, sedative activities of these classes of drugs depend on variations in binding characteristics to the alpha1 subunit of the gamma-amino butyric acidA-receptor, which inhibits neuronal activity in broad areas of the brain and is found in areas of the brain responsible for sleep/wakefulness and sedation. However, nonbenzodiazepines with a rapid onset of action and short half-life have shown limited efficacy for maintaining sleep throughout the night. These properties have contributed to the development of modified-release formulations. Zolpidem extended-release is a bilayer tablet that retains the fast onset of action of its parent compound zolpidem while extending the duration of hypnotic activity, owing to a slower-release portion of the tablet.

CONCLUSIONS

Based on clinical evidence, the risk of residual next-day effects of zolpidem extended-release is limited, mainly due to the similarly short half-life in its extended-release formulation.

Long-term efficacy and safety of zolpidem extended-release 12.5 mg, administered 3 to 7 nights per week for 24 weeks, in patients with chronic primary insomnia: a 6-month, randomized, double-blind, placebo-controlled, parallel-group, multicenter study

STUDY OBJECTIVES

To evaluate long-term efficacy and safety of zolpidem extended-release 3 to 7 nights/week for chronic primary insomnia.

DESIGN

Multicenter, 25-week, phase IIIb, randomized, double-blind, placebo-controlled, parallel-group.

SETTING

Outpatient; visits every 4 weeks.

PATIENTS

Aged 18 to 64 years; DSM-IV criteria for chronic primary insomnia; > or =3 months of difficulty initiating or maintaining sleep or experiencing nonrestorative sleep.

INTERVENTIONS

Single-dose zolpidem extended-release 12.5 mg (n = 669) or placebo (n = 349), self-administered from a minimum of 3 nights/week to a maximum of 7 nights/week.

MEASUREMENTS AND RESULTS

Patient's Global Impression (PGI) and Clinical Global Impression-Improvement (CGI-I) were assessed every 4 weeks up to week 24. Patient Morning Questionnaire (PMQ), recorded daily, assessed subjective sleep measures-sleep onset latency (SOL), total sleep time (TST), number of awakenings (NAW), wake time after sleep onset (WASO), and quality of sleep (QOS)-and next-day functioning. At week 12, PGI, Item 1 (aid to sleep), the primary endpoint, was scored as favorable (i.e., "helped me sleep") by 89.8% of zolpidem patients vs. 51.4% of placebo patients (P < 0.0001, based on rank score) and at week 24 by 92.3% of zolpidem extended-release patients vs. 59.7% of placebo patients. Zolpidem extended-release also was statistically significantly superior to placebo at every time point for PGI (Items 1-4) and CGI-I (P < 0.0001, rank score), TST, WASO, QOS (P < 0.0001), and SOL (P < or = 0.0014); NAW (Months 2-6; P < 0.0001). Sustained improvement (P < 0.0001, all time points) was observed in morning sleepiness and ability to concentrate (P = 0.0014, month 6) with zolpidem extended-release compared with placebo. Most frequent adverse events for zolpidem extended-release were headache, anxiety and somnolence. No rebound effect was observed during the first 3 nights of discontinuation.

CONCLUSIONS

These findings establish the efficacy of 3 to 7 nights per week dosing of zolpidem extended-release 12.5 mg for up to 6 months. Treatment provided sustained and significant improvements in sleep onset and maintenance and also improved next-day concentration and morning sleepiness.

Efficacy and safety of zolpidem extended release in elderly primary insomnia patients

OBJECTIVES

To evaluate the clinical efficacy and safety of zolpidem extended release for the treatment of primary insomnia in elderly patients.

METHODS

A randomized, double-blind, placebo-controlled, parallel-group clinical trial was conducted. A total of 205 (117 women, 88 men; mean age 70.2 +/- 4.5 years) Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition-defined primary insomnia patients were randomized to 3 weeks of nightly treatment with either zolpidem extended release 6.25 mg or placebo; 198 patients completed the study.

RESULTS

Relative to placebo, zolpidem extended release 6.25 mg significantly decreased wake time after sleep onset during the first six hours of the night, as measured by polysomnogram (PSG). PSG latency to persistent sleep was reduced and PSG total sleep time was increased, both at nights 1/2 and 15/16. Patient self-report measures were significantly better with zolpidem extended-release 6.25 mg than with placebo throughout treatment. Some PSG measures indicated a worsening of sleep for a single night after abrupt discontinuation of zolpidem extended release. No next-morning residual effects were observed. The overall incidence and nature of adverse events was comparable between the two groups.

CONCLUSIONS

Zolpidem extended release 6.25 mg improved both sleep maintenance and sleep induction in elderly primary insomnia patients during three weeks of administration.

Zolpidem Extended-Release: A Single Insomnia Treatment Option for Sleep Induction and Sleep Maintenance Symptoms

It is imperative that primary care clinicians have a thorough understanding of insomnia, because they are often the first point of contact for patients who seek assistance when they have difficulty sleeping. Insomnia may appear with different presentations: sleep onset, sleep maintenances, sleep offset, nonrestorative sleep, or a combination of these symptoms. Untreated symptoms result in clinically significant distress or impairment in social, occupational, or other important areas of following-day functionality. Physicians, pharmacists, and other clinicians should be aware of the conditions that contribute to, are antecedent to, and associated with insomnia. These pathophysiological conditions include advanced age; female gender; respiratory, gastrointestinal, vascular, and rheumatologic pain syndromes; and other conditions such as depression and/or anxiety. Additional health factors contributing to insomnia include chronic pain, stressors, grief reaction, pharmacotherapeutic side effects, lifestyle contributors such as social/recreational drugs, phytopharmaceuticals, and ethanol use. The pharmacotherapy focus in this article is a modified-release formulation of the BZ1 (omega1) receptor agonist zolpidem, zolpidem extended-release. Pharmacokinetic, pharmacodynamic, and safety studies that compare 12.5 mg zolpidem extended-release (Ambien CRtrade markCIV) and 10 mg original zolpidem were initially conducted in healthy volunteers to assess the potential for an improved clinical profile. Zolpidem extended-release (12.5 mg and 6.25 mg extended-release dosage forms) is indicated for the treatment of insomnia characterized by difficulties with sleep onset and/or sleep maintenance. Zolpidem extended-release is devoid of any short-term use limitation and can be prescribed for the duration of medical necessity. The modified-release zolpidem is a two-layer tablet with a biphasic release profile, releasing the first layer immediately, whereas the second layer is released at a slower rate. Plasma concentrations are maintained for a longer period of time versus the immediate-release zolpidem formulation. Pharmacokinetic analysis has also demonstrated that the time to maximum concentration (tmax) and terminal elimination half-life (t1/2) of 12.5 mg zolpidem extended-release are similar to those of 10 mg zolpidem indicating a similar rapid onset of action and an elimination profile that reduced the risk of next-day decrements in performance. Zolpidem's CYP 450 hepatic metabolism uses as a substrate CYP3A4 (major) and 1A2, 2C9, 2C19, and 2D6 as minor pathways. Zolpidem extended-release dosage forms diminish sleep latency, number of awakenings, and wakefulness after sleep onset and augments total time asleep.

Insomnia: zolpidem extended-release for the treatment of sleep induction and sleep maintenance symptoms

Insomnia impairs daytime functioning or causes clinically significant daytime distress. The consequences of insomnia, if left untreated, may contribute to the risks of developing additional serious conditions, such as psychiatric illness, cardiovascular disease, or metabolic issues. Furthermore, some comorbidities associated with insomnia may be bidirectional in their causality because psychiatric and other medical problems can increase the risk for insomnia. Regardless of the serious consequences of inadequately treated insomnia, clinicians often do not inquire into their patients' sleep habits, and patients, in turn, are not forthcoming with details of their sleep difficulties. The continuing education of physicians and patients with regard to insomnia and currently available therapies for the treatment of insomnia is, therefore, essential. Insomnia may present as either a difficulty falling asleep, difficulty maintaining sleep, or waking too early without being able to return to sleep. Furthermore, these symptoms often change over time in an unpredictable manner. Therefore, when considering a sleep medication, one with efficacy for the treatment of multiple insomnia symptoms is recommended. A modified-release formulation of zolpidem, zolpidem extended-release, has been approved for the treatment of insomnia characterized by both difficulty in falling asleep and maintaining sleep. Here, we review studies supporting the use of zolpidem extended-release in the treatment of sleep-onset and sleep maintenance difficulties.

Zolpidem extended-release

Zolpidem extended-release, or controlled-release (CR), is a new formulation of zolpidem, a nonbenzodiazepine hypnotic. It is indicated in the US for the treatment of insomnia, characterised by difficulties with sleep onset and/or sleep maintenance. Zolpidem CR is a dual-layered tablet; one layer releases zolpidem immediately and a second layer provides a slower release of additional zolpidem for maintenance of plasma zolpidem concentrations. Efficacy of zolpidem CR was assessed in two 3-week, randomised, double-blind, placebo-controlled, phase III polysomnography trials in younger adult (aged 18-64 years) or elderly (aged > or =65 years) patients with primary insomnia. Patients received nightly zolpidem CR (12.5mg in younger adult and 6.25mg in elderly patients). Efficacy was assessed objectively on nights 1, 2, 15 and 16. Patients who received zolpidem CR had significantly improved objective latency to persistent sleep, wake time after sleep onset and sleep efficiency on assessment nights compared with placebo recipients. In subjective assessments of sleep quality on day 2 and nights 15 and 22, significantly more zolpidem CR than placebo recipients gave favourable responses on a Patient Global Impression scale in the study in younger adult patients. In the other study, significantly more elderly patients in the zolpidem CR group rated their sleep as improved compared with the placebo group. Zolpidem CR was generally well tolerated and appears to have a tolerability profile similar to that of the original formulation of zolpidem.