Pharmacokinetics and metabolism of zopiclone

Residual effects of zopiclone on driving performance using a standardized driving simulator among healthy volunteers

RATIONALE

The effects of hypnotics on automobile driving have been attracting increasing attention. However, few driving simulators (DSs) have been confirmed to have acceptable reliability and validity for assessing the next-day residual effects of zopiclone as a positive control on driving performance.

OBJECTIVE

To investigate whether a new DS could permit detection of the next-day residual effects of zopiclone on driving performance.

METHODS

In this double-blind, randomized, placebo-controlled crossover trial, 28 healthy males received zopiclone 7.5 mg at bedtime on days 1 and 8 and placebo on the other days over a period of 16 days. The participants took part in three driving tasks-road-tracking, car-following, and harsh-braking-using a DS on days 2 and 9 at 9-h post-dosing. Scores on the Karolinska Sleepiness Scale and Profile of Mood States-Second Edition were then assessed, as was the serum concentration of zopiclone.

RESULTS

The estimated differences in the standard deviation of lateral position (cm) in the road-tracking task between the zopiclone and placebo groups on days 2 and 9 were 3.75 cm (90% confidence interval (CI): 1.71-5.79) and 4.07 cm (90% CI: 2.02-6.11), respectively. The estimated differences in the distance coefficient of variation in the car-following task and in the brake reaction time in the harsh-braking task between the zopiclone and placebo groups on day 2 were 4.31 (90% CI: 1.94-6.69) and 24.6 ms (90% CI: 12.7-36.4), respectively.

CONCLUSIONS

The DS used in this study has sufficient sensitivity to detect the next-day residual effects of zopiclone on driving performance.

Eszopiclone and Zolpidem Produce Opposite Effects on Hippocampal Ripple Density

Clinical populations have memory deficits linked to sleep oscillations that can potentially be treated with sleep medications. Eszopiclone and zolpidem (two non-benzodiazepine hypnotics) both enhance sleep spindles. Zolpidem improved sleep-dependent memory consolidation in humans, but eszopiclone did not. These divergent results may reflect that the two drugs have different effects on hippocampal ripple oscillations, which correspond to the reactivation of neuronal ensembles that represent previous waking activity and contribute to memory consolidation. We used extracellular recordings in the CA1 region of rats and systemic dosing of eszopiclone and zolpidem to test the hypothesis that these two drugs differentially affect hippocampal ripples and spike activity. We report evidence that eszopiclone makes ripples sparser, while zolpidem increases ripple density. In addition, eszopiclone led to a drastic decrease in spike firing, both in putative pyramidal cells and interneurons, while zolpidem did not substantially alter spiking. These results provide an explanation of the different effects of eszopiclone and zolpidem on memory in human studies and suggest that sleep medications can be used to regulate hippocampal ripple oscillations, which are causally linked to sleep-dependent memory consolidation.

Treatment of depression: Are psychotropic drugs appropriately dosed in women and in the elderly? Dosages of psychotropic drugs by sex and age in routine clinical practice

BACKGROUND

Several researchers have shown higher concentration-dose ratios of psychotropic drugs in women and the elderly. Therefore, lower dosages of psychotropic drugs may be recommended in women and the elderly. This study describes sex- and age-related dosage of psychotropic drugs prescribed to patients with major depressive disorder (MDD) in routine clinical practice.

METHOD

Influence of sex and age on dosages are analysed for the 10 most commonly prescribed drugs in our dataset consisting of 32,082 inpatients with MDD. Data stems from the European drug safety program "Arzneimittelsicherheit in der Psychiatrie". The observed sex and age differences in prescriptions are compared to differences described in literature on age- and gender-related pharmacokinetics.

RESULTS

Among patients over 65 years, a statistically significant decrease in dosages with increasing age (between 0.65% and 2.83% for each increasing year of age) was observed, except for zopiclone. However, only slight or no influence of sex-related adjustment of dosage in prescriptions was found.

CONCLUSION

Age appears to influence adjustment of dosage in most psychotropic drugs, but to a lower extent than data on age-related pharmacokinetics suggests. Although literature also suggests that lower dosages of psychotropic drugs may be appropriate for females, this study found women are usually prescribed the same dosage as men.

An explorative approach to understanding individual differences in driving performance and neurocognition in long-term benzodiazepine users

OBJECTIVE

Previous research reported cognitive and psychomotor impairments in long-term users of benzodiazepine receptor agonists (BZRAs). This article explores the role of acute intoxication and clinical complaints.

METHODS

Neurocognitive and on-road driving performance of 19 long-term (≥6 months) regular (≥twice weekly) BZRA users with estimated plasma concentrations, based on self-reported use, exceeding the therapeutic threshold (C_BZRA +), and 31 long-term regular BZRA users below (C_BZRA -), was compared to that of 76 controls.

RESULTS

BZRA users performed worse on tasks of response speed, processing speed, and sustained attention. Age, but not C_BZRA or self-reported clinical complaints, was a significant covariate. Road-tracking performance was explained by C_BZRA only. The C_BZRA  + group exhibited increased mean standard deviation of lateral position comparable to that at blood-alcohol concentrations of 0.5 g/L.

CONCLUSIONS

Functional impairments in long-term BZRA users are not attributable to self-reported clinical complaints or estimated BZRA concentrations, except for road-tracking, which was impaired in CBZRA + users. Limitations to address are the lack of assessment of objective clinical complaints, acute task related stress, and actual BZRA plasma concentrations. In conclusion, the results confirm previous findings that demonstrate inferior performance across several psychomotor and neurocognitive domains in long-term BZRA users.

Metabolic N-Dealkylation and N-Oxidation as Elucidators of the Role of Alkylamino Moieties in Drugs Acting at Various Receptors

Metabolic reactions that occur at alkylamino moieties may provide insight into the roles of these moieties when they are parts of drug molecules that act at different receptors. N-dealkylation of N,N-dialkylamino moieties has been associated with retaining, attenuation or loss of pharmacologic activities of metabolites compared to their parent drugs. Further, N-dealkylation has resulted in clinically used drugs, activation of prodrugs, change of receptor selectivity, and providing potential for developing fully-fledged drugs. While both secondary and tertiary alkylamino moieties (open chain aliphatic or heterocyclic) are metabolized by CYP450 isozymes oxidative N-dealkylation, only tertiary alkylamino moieties are subject to metabolic N-oxidation by Flavin-containing monooxygenase (FMO) to give N-oxide products. In this review, two aspects will be examined after surveying the metabolism of representative alkylamino-moieties-containing drugs that act at various receptors (i) the pharmacologic activities and relevant physicochemical properties (basicity and polarity) of the metabolites with respect to their parent drugs and (ii) the role of alkylamino moieties on the molecular docking of drugs in receptors. Such information is illuminative in structure-based drug design considering that fully-fledged metabolite drugs and metabolite prodrugs have been, respectively, developed from N-desalkyl and N-oxide metabolites.

Comparative study of the effects of zopiclone (7.5 mg), zolpidem, flunitrazepam and a placebo on nocturnal cognitive performance in healthy subjects, in relation to pharmacokinetics

The effect of zopiclone (7.5 mg) on attention, vigilance and memory components was evaluated during a nocturnal period in comparison to a placebo, to zolpidem (10 mg) and to flunitrazepam (1 mg) in a double blind, randomized study, after administration of a single dose in 16 young healthy volunteers. It appears that there is a clear effect on attention and vigilance; this effect is apparent during the kinetic phase of the absorption of the medication. The effect on memory is transient and is absent four hours after the ingestion of the drug. The objective results are not strictly consistent with the chronology of the subjective parameters (Leeds scale — Visual Analogue Scale). The three hypnotics under comparison do not fundamentally differ except in their kinetic/pharmacodynamic effect relationship. One important fact, taking the parameters as a whole, is that there is no objective “residual” effect.

Women's Psychiatry

Brain disorders and mental diseases, in particular, are common and considered as a top global health challenge for the twenty-first century. Interestingly, women suffer more frequently from mental disorders than men. Moreover, women may respond to psychotropic drugs differently than men, and, through their lifespan, they endure sex-orientated social stressors. In this chapter, we present how women may differ in the development and manifestation of mental health issues and how they differ from men in pharmacokinetics and pharmacodynamics. We discuss issues in clinical trials regarding women participation, issues in the use of psychotropic medications in pregnancy, and challenges that psychiatry faces as a result of the wider use of contraceptives, of childbearing at older age, and of menopause. Such issues, among others, demand further women-oriented psychiatric research that can improve the care for women during the course of their lives. Indeed, despite all these known sex differences, psychiatry for both men and women patients uses the same approach. Thereby, a modified paradigm for women's psychiatry, which takes into account all these differences, emerges as a necessity, and psychiatric research should take more vigorously into account sex differences.

Simulations of Cytochrome P450 3A4-Mediated Drug-Drug Interactions by Simple Two-Compartment Model-Assisted Static Method

In order to predict cytochrome P450 3A4 (CYP3A4)-mediated drug-drug interactions (DDIs), a simple 2-compartment model-assisted, overall inhibition activity (A_i,overall) method was derived based on 2 concepts. One concept was that the increase in blood victim level and fold increase in the area under the blood victim level curve produced by DDI are determined entirely by A_i,overall, the hepatic availability of the victim and fraction of urinary excreted unchanged victim, where A_i,overall is determined by the perpetrator-specific CYP isoform inhibition activities (A_i,CYPs, DDI predictor-1) and victim-specific fractional CYP isoform contributions (f_m,CYPs, predictor-2). The other concept was that a DDI can be bridged to other DDIs, so that any possible DDI produced by a given victim or a given perpetrator can be predicted by using these predictors. The A_i,CYP3A4s of 12 common CYP3A4 inhibitors were able to be determined and shown to be useful for the prediction of CYP3A4-mediated DDIs wherein victims were metabolized by multiple CYP isoforms. Additionally, it was demonstrated that f_m,CYP values with high confidence can be estimated by bridging DDIs produced by the same victim and different perpetrators. This bridging approach will accelerate prediction of DDIs produced by new chemical entities from the existing DDI database.

Occipital event-related potentials to addiction-related stimuli in detoxified patients with alcohol dependence, and their association with three-month relapse

BACKGROUND

Understanding the biological underpinnings of relapse in alcohol dependency is a major issue in addiction research. Based on recent evidence regarding the relevance of occipital visual evoked response potentials (ERPs) in addiction research, and its significance for relapse research, we assessed occipital ERPs to alcohol- and non-alcohol-related stimuli in recently detoxified patients and controls.

METHODS

Thirty recently detoxified patients with alcohol addiction, and 31 healthy control subjects, were assessed in a Go and a NoGo condition, each using three visual stimuli: tea, juice and beer. In the "Go" condition, subjects had to respond to the juice (12.5 %) and the beer stimulus (12.5 %), and ignore the tea picture (75 %). In the "NoGo" condition, subjects had to respond to the tea picture (75 %) and ignore the juice and the beer picture (12.5 % each). The subjects' EEGs were analyzed with regard to the occipital P100 and N170 ERP components. Patients were then evaluated for relapse 3 months after this initial assessment.

RESULTS

P100 amplitudes differed between conditions and between stimuli, and we found a condition x electrode interaction. However, none of these P100 results involved group or relapse-status effects. N170 amplitudes in patients were elevated as compared to controls. Additionally, patients' heightened N170 amplitudes in response to the alcohol-related (beer) stimulus were found only under the NoGo condition, where subjects had to react to the frequent tea stimulus and ignore the beer and the juice stimuli, thus resulting in a condition x stimulus x group interaction. Patients reporting relapse in a 3-month follow-up assessment showed larger NoGo N170 alcohol cue-related ERP amplitudes and increased depression scores as compared to patients who stayed abstinent. Depression was related to shortened P100 latencies in patients, but unrelated to the N170 NoGo cue-reactivity effect.

CONCLUSIONS

Our results indicate a sensitivity of occipital ERPs to addiction-related stimuli when these act as non-targets. Recently detoxified patients may be vulnerable to addiction-related cues when these occur outside the focus of directed attention, thereby circumventing intentional control processes. Furthermore, ERPs to addiction-related stimuli may be useful as a predictor of abstinence success in recently detoxified patients.

Low resolution and high resolution MS for studies on the metabolism and toxicological detection of the new psychoactive substance methoxypiperamide (MeOP)

In 2013, the new psychoactive substance methoxypiperamide (MeOP) was first reported to the European Monitoring Centre for Drug and Drug Addiction. Its structural similarity to already controlled piperazine designer drugs might have contributed to the decision to offer MeOP for online purchase. The aims of this work were to identify the phase I/II metabolites of MeOP in rat urine and the human cytochrome P450 (CYP) isoenzymes responsible for the initial metabolic steps. Finally, the detectability of MeOP in rat urine by gas chromatography-mass spectrometry (GC-MS) and liquid chromatography coupled with multistage mass spectrometry (LC-MS(n)) standard urine screening approaches (SUSAs) was evaluated. After sample preparation by cleavage of conjugates followed by extraction for elucidating phase I metabolites, the analytes were separated and identified by GC-MS as well as liquid chromatography-high resolution-tandem mass spectrometry (LC-HR-MS/MS). For detection of phase II metabolites, the analytes were separated and identified after urine precipitation followed by LC-HR-MS/MS. The following metabolic steps could be postulated: hydrolysis of the amide, N-oxide formation, N- and/or O-demethylation, oxidation of the piperazine ring to the corresponding keto-piperazine, piperazine ring opening followed by oxidation of a methylene group to the corresponding imide, and hydroxylation of the phenyl group. Furthermore, N-acetylation, glucuronidation and sulfation were observed. Using human CYPs, CYP1A2, CYP2C19, CYP2D6, and/or CYP3A4 were found to catalyze N-oxide formation and N-, O-demethylation and/or oxidation. Mostly MeOP and N-oxide-MeOP but to a minor degree also other metabolites could be detected in the GC-MS and LC-MS(n) SUSAs.

Zopiclone's residual effects on actual driving performance in a standardized test: a pooled analysis of age and sex effects in 4 placebo-controlled studies

BACKGROUND

In many European countries, Canada, and Japan, the nonbenzodiazepine zopiclone is now among the most frequently prescribed hypnotic drugs. This finding can be explained by the growing view among physicians that zopiclone is more effective and safer than conventional benzodiazepines. However, in 4 studies using similar procedures, it has been shown that zopiclone 7.5 mg causes moderate to severe impairment in driving performance.

OBJECTIVE

The goal of the present article was to review these studies and analyze the pooled data to determine whether the severity of effects is modified by the sex and age of the subjects.

METHODS

The driving data of the placebo and zopiclone 7.5 mg evening treatment periods from a total of 4 studies conducted at Maastricht University were included in this pooled analysis. All studies were conducted according to balanced double-blind, crossover designs. The effects on driving were always measured the next morning, between 10 and 11 hours after administration, by using a standardized highway driving test. A total of 101 healthy volunteers of both sexes in equal proportions (with no reports of insomnia) participated. Subjects comprised young volunteers (age range, 21-45 years) in 3 studies and older volunteers (age range, 55-75 years) in the fourth study.

RESULTS

Results show that zopiclone 7.5 mg has significant and clinically relevant performance-impairing effects on driving in the morning, until 11 hours after bedtime ingestion. The effects did not differ between male and female subjects and did not increase with age, at least until 75 years. The effects of zopiclone 7.5 mg are comparable to the effects of a mean blood alcohol concentration between 0.5 and 0.8 mg/mL, which has been associated with a 2- to 3-fold increase in the risk of becoming involved in a traffic accident.

CONCLUSIONS

We concluded that patients using an evening dose of zopiclone 7.5 mg should avoid activity in skilled work and participation in traffic the morning after intake. General practitioners' beliefs regarding the beneficial safety profile of zopiclone may need adjustment, and patients using zopiclone 7.5 mg should be warned accordingly. There is no need to differentiate warnings about zopiclone's residual impairing effects depending on the sex of the patient.

The CYP2C8 inhibitor gemfibrozil does not increase the plasma concentrations of zopiclone

OBJECTIVE

Zopiclone is a short acting hypnotic, which is metabolised by cytochrome P450 (CYP) 3A4 and 2C8 in vitro. We studied the possible effect of gemfibrozil, an inhibitor of CYP2C8, on the pharmacokinetics and pharmacodynamics of zopiclone.

METHODS

In a randomised 2-phase crossover study, 10 healthy volunteers took 600 mg gemfibrozil or placebo orally twice daily for 3 days. On day 3, each ingested a 7.5 mg dose of zopiclone. Plasma concentrations and urinary excretion of zopiclone and its two primary metabolites, plasma gemfibrozil, and psychomotor performance were measured. The effects of CYP2C8, CYP2C9 and CYP3A4 inhibitors on the depletion of zopiclone (500 nM) were studied in vitro in human liver microsomes.

RESULTS

The pharmacokinetic variables of the parent zopiclone were not significantly affected by gemfibrozil. However, gemfibrozil raised the mean peak plasma concentration (C(max)) of N-oxide-zopiclone (1.6-fold; P<0.001) and that of N-desmethyl-zopiclone (1.2-fold; P<0.001). The mean area under the plasma concentration-time curve (AUC(0)-infinity) values of N-oxide-zopiclone and N-desmethyl-zopiclone were raised 2-fold (P<0.001) and 1.2-fold (P<0.01), respectively. The renal clearance of N-oxide-zopiclone was reduced by 48% by gemfibrozil (P<0.001). The pharmacodynamic effects of zopiclone, measured using psychometric tests, were not affected by gemfibrozil. In vitro, ketoconazole (1 microM) and itraconazole (8 microM) decreased the elimination rate of zopiclone enantiomers by about 65-95%, while montelukast (16 microM), gemfibrozil (200 microM) and sulfaphenazole (10 microM) had no appreciable effect.

CONCLUSIONS

Gemfibrozil does not increase the plasma concentrations of the parent zopiclone. Accordingly, CYP2C8 does not significantly metabolise zopiclone in vivo. However, as gemfibrozil raises the concentrations of two potentially active metabolites of zopiclone, slightly enhanced effects of zopiclone by gemfibrozil can not be excluded.

Quantitation of zopiclone and desmethylzopiclone in human plasma by high-performance liquid chromatography using fluorescence detection

A simple, reliable HPLC method using fluorescence detection (excitation 307 and emission 483 nm) was developed and validated for simultaneous quantitation of zopiclone and its metabolite desmethylzopiclone in human plasma. Following a single-step liquid-liquid extraction, the analytes and internal standard (zaleplon) were separated using an isocratic mobile phase on a reversed-phase C18 column. The lower limit of quantitation was 3 ng/mL for zopiclone and 6 ng/mL for desmethylzopiclone with a relative standard deviation of less than 5%. A linear dynamic range of 3-300 ng/mL for zopiclone and of 6-500 ng/mL for desmethylzopiclone was established. This HPLC method was validated with between-batch precision of 1.7-4.2% and 3.2-7.5% for zopiclone and desmethylzopiclone respectively. The between-batch accuracy was 99.4-111.5% and 101.6-104.8% for zopiclone and desmethylzopiclone, respectively. Frequently coadministered drugs did not interfere with the described methodology. Stability of zopiclone and desmethylzopiclone in plasma was excellent, with no evidence of degradation during sample processing (autosampler) and 30 days' storage in a freezer. This validated method is simple and repeatable enough to be used in pharmacokinetic studies.

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

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

Zopiclone, but not brotizolam, impairs memory storage during sleep

We compared the effect of a single bedtime dose of two short half-time hypnotics, brotizolam (0.25 mg) and zopiclone (7.5 mg), on memory storage during sleep in a double blind, placebo-controlled, three-way crossover design trial in eight healthy volunteers. Memory was evaluated using a standard word list free-recall test learned before the bedtime dose by the subjects, who were asked to remember the list the following morning. Digit Symbol Substitution Test revealed no residual sedation by brotizolam or zopiclone. Brotizolam did not affect the morning recall compared to placebo, but subjects remembered less words under zopiclone treatment, suggesting that this drug could affect memory storage during sleep.

Effects of short-acting hypnotics on sleep latency in rats placed on grid suspended over water

The present study was performed to develop a new sleep disturbance model for evaluating hypnotic potencies by placing rats on a grid suspended over water up to 1 cm under the grid surface. When rats were placed on the grid, significant increases in sleep latency and amount of wakefulness were observed compared with those of rats placed on sawdust. However, the amounts of non-rapid eye movement (non-REM) sleep and rapid eye movement (REM) sleep of rats placed on the grid were significantly decreased compared with those of rats placed on sawdust. Four short-acting hypnotics (triazolam, zopiclone, brotizolam, lormetazepam) caused significant decreases in sleep latency, and the effects of hypnotics in rats placed on the grid were more potent than those in rats placed on sawdust. In conclusion, the present model can serve as a new sleep disturbance model and may also be useful for evaluating the sleep-inducing effects of short-acting hypnotics.

Molecular actions of (S)-desmethylzopiclone (SEP-174559), an anxiolytic metabolite of zopiclone

This study set out to profile the activity of (S)-desmethylzopiclone (SEP-174559) at subtypes of the gamma-aminobutyric acid type-A (GABA(A)) receptor and other neurotransmitter receptor ion channels. Recombinant receptors were expressed in human embryonic kidney 293 cells and examined functionally by patch-clamp recording with fast perfusion of agonist and drug solutions. Micromolar concentrations of SEP-174559 potentiated GABA(A) receptor currents evoked by subsaturating concentrations of GABA. The potentiation was related to a leftward shift in the GABA dose-response curves, suggesting the drug acts to increase GABA binding affinity. The potentiation strictly required the presence of the gamma2 subunit; no enhancement was seen for receptors containing instead the gamma1 subunit or lacking a gamma subunit altogether. SEP-174559 and its parent compound, racemic zopiclone, were not selective between alpha1-, alpha2-, or alpha3-bearing GABA(A) receptors. Within the nicotinic receptor superfamily, SEP-174559 did not affect serotonin type-3 receptor function but was found to inhibit nicotinic acetylcholine (nACh) receptors. The inhibition of nACh receptors was noncompetitive and was mimicked by zopiclone, alprazolam, and diazepam. In the glutamate receptor superfamily, SEP-174559 inhibited N-methyl-D-aspartate (NMDA) receptor currents but did not affect non-NMDA receptors. These data confirm that SEP-174559 has benzodiazepine-like actions at gamma2-bearing subtypes of the GABA(A) receptor and suggest additional actions of benzodiazepine-site ligands at nACh and NMDA receptors.

Validation of a high-performance liquid chromatographic method for the enantiospecific quantitation of zopiclone in plasma

Zopiclone is a hypnosedative with clinical effects similar to benzodiazepines but thought to have less potential for rebound insomnia and withdrawal effects. Zopiclone is administered as a racemic mixture, and an enantiospecific method of analysis of zopiclone in plasma is desirable in the study of pharmacokinetic drug interactions. We report a modification of an HPLC method reported by Foster et al. using a closely related structural analogue of zopiclone as internal standard. Zopiclone was detected at 306 nm and linear calibration curves were constructed in the range of 1.0-250 ng/mL for each enantiomer. The % CV at 2.5 ng/mL was 12.0% for (-)-zopiclone and 14.3% for (+)-zopiclone, and the limit of quantification of each enantiomer was 2.5 ng/mL. At higher concentrations, the coefficient of variation was less than 10%. The nominal concentration of quality control samples was predicted with an accuracy within a range of +/-11.6%. The method was used in the analysis of plasma obtained from psychiatric patients. One sample obtained following a non-fatal overdose with zopiclone contained the metabolites (-)-N-oxide zopiclone and both enantiomers of desmethyl zopiclone. The metabolite enantiomers were resolved on the column with retention times similar to zopiclone. The N-oxide metabolite co-eluted with internal standard.

Comparative effects of zopiclone and loprazolam on psychomotor and physical performance in active individuals

OBJECTIVE

Sedative hypnotics are used by athletes to alleviate precompetition anxiety and insomnia. The effects of these agents on exercise tolerance have not been extensively researched.

DESIGN

To determine the effects of sedative hypnotics on psychomotor and physical performance, a double-blind, placebo- (P) controlled, cross-over designed trial investigated the effects of zopiclone (Z) and loprazolam (L) on performance in 12 athletes.

INTERVENTION

Subjects ingested either P, Z (7.5 mg), or L (2 mg) on three different occasions separated by a 1-week washout period. Eye-hand coordination tests, a 30-m sprint test, an agility test, and a graded treadmill run to exhaustion for determination of VO2max were performed 10 hours after drug administration.

RESULTS

Subjects reported a significantly greater hangover effect following ingestion of L (8/11 subjects) compared with ingestion of Z (3/11 subjects; p < 0.01). A greater number of subjects felt alert after ingestion of P (9/11 subjects) and Z (9/11 subjects) compared with L (4/11 subjects; p < 0.01). The results of the eye-hand coordination tests, the 30-m sprint, the T-test, the VO2max, and the time to exhaustion during the treadmill run were not significantly altered following the ingestion of P, Z, and L. There was a significant difference between the delta values for Z and L for the number of missed responses in the eye-hand coordination tests (p < 0.02). Therefore, following the ingestion of L, subjects experienced a significant hangover effect and altered reaction time, whereas the ingestion of Z did not significantly impair either psychomotor or physical performance in the administered tests.

CLINICAL RELEVANCE

Investigate the extent of the effects of sedative hypnotics on exercise performances, enabling team physicians to prescribe such drugs to the athlete more effectively.

A guide to the safety of CNS-active agents during breastfeeding

For most agents with CNS activity, there are limited data regarding their safety in breastfeeding. Any decision to institute treatment for a neurological or psychiatric disorder must weigh the benefits of maternal treatment against the potential harm to the breastfeeding mother of withholding medication which may improve her illness. For the neonate, one must balance the risk of medication exposure against the benefit of receiving breast milk. Most tricyclic antidepressants can be used in lactating women. Because of the limited data, selective serotonin (5-hydroxytryptamine; 5-HT) reuptake inhibitors should only be used with due consideration of the potential adverse effects. Breastfeeding is best avoided by women who require lithium therapy, because of both the immature excretory systems in the infant and relatively high doses received by the infant. There is little information about the safety of antipsychotic medications in breastfeeding. Concerns include toxicity and abnormal neurological development in the infant. These agents may be used with caution. Most agents which cause depression of the CNS, including opiates and sedatives, can be used in small doses and for short courses in breastfeeding mothers. Most anticonvulsants can be used in lactating women. Reference texts and consultation with experts are useful adjuncts to discussion of the risks and benefits of therapy with the patient. The scope of this review is limited to drugs with therapeutic uses, thus drugs of abuse are not discussed, nor are caffeine and alcohol (ethanol).

Detection and quantification of the hypnotic zopiclone, connected with an uncommon case of drowning

A fatality, attributed to a suicidal ingestion of zopiclone and subsequent death by drowning, is described. A radioimmunoassay was performed to prescreen for the presence of the analyte. HPLC analysis with fluorescence detection demonstrated a testicular tissue concentration of 2.2 micrograms/g zopiclone. Further toxicological analysis revealed also the presence of diazepam in a concentration of 150 ng/g.

Development of a stereospecific radioimmunoassay for the analysis of zopiclone and metabolites in urine

A sensitive and specific radioimmunoassay has been developed, allowing the stereospecific detection of nanogram amounts of (+)- and (-)-enantiomers of zopiclone and its major metabolites in urine, without prior extraction or purification. Antisera were obtained from two series of four rabbits, immunized with optically pure (+)- and (-)-N-hemisuc-cinyldesmethylzopiclone, conjugated to bovine serum albumin according to the active ester method. The assay was stereospecific, allowing discrimination between the two enantiomers of N-desmethylzopiclone with mutual cross-reactivities below 2%. Substantial cross-reaction was observed with the parent compound, although lower than expected, and to a lesser extent with the N-oxide metabolite. A selection of hypnotics, anxiolytics, antidepressants and some other widely used drugs did not interfere with the assay (< 0.1%), when tested at a concentration level of 10 micrograms/ml. The sensitivity of the assay was 50 pg/ml and 10 pg/ml for the (+)- and (-)-enantiomers, respectively. The binding assay described here was used to evaluate the stereoselective excretion pattern of zopiclone. Analysis of cumulative excretion samples from a volunteer revealed a mean metabolic excretion ratio (+)/(-) of 2.2, ranging from 1.7 (7 h) to 4.4 (36 h) A mean excretion ratio (+)/(-) of 2.5 +/- 1 was calculated after analysis of urine samples from 20 patients receiving zopiclone as a hypnotic daily.

Enantioselective determination of zopiclone and its metabolites in urine by capillary electrophoresis

A method has been developed for the stereoselective determination of zopiclone and its main metabolites in urine. After the addition of the internal standard zolpidem the urine samples were extracted at pH 8 with chloroform-isopropanol (9:1). Analyses were carried out using capillary electrophoresis (CE) with beta-cyclodextrin as the chiral selector. The analytes were detected using UV laser-induced fluorescence detection with a He-Cd laser operated at 325 nm. Urine samples of two volunteers after oral administration of 7.5 mg zopiclone were investigated. The S-(+)-enantiomers of zopiclone and its metabolites were always excreted in higher amounts than the R-(-)-enantiomers. With the same method the zopiclone enantiomers were quantified in saliva. Compared to high-performance liquid chromatography, the CE method is very fast and simple.

Interactions and comparative effects of zopiclone, diazepam and lorazepam on psychomotor performance and on elimination pharmacokinetics in healthy volunteers

A randomised, placebo-controlled, double blind single-dose cross-over study was arranged to investigate possible interactions between zopiclone (7.5 mg) and two widely used benzodiazepine (BZD) anxiolytics diazepam (5 mg) and lorazepam (1 mg) during the elimination phase of drugs. Psychomotor performance was tested before and 1, 6, 8, 12 and 24 hr after the drug administration. Simultaneously, blood samples were drawn for determination of plasma drug concentrations. The elimination of each compound was not altered by coadministration of other drugs. As expected, one hour after drug ingestion, psychomotor performance was impaired. The coadministration of drugs increased the effect. During the elimination phase, 6 and 8 hr after the drug intake, only zopiclone and lorazepam in combination slightly impaired performance as compared with the pretreatment levels, but there was no difference as compared with placebo. Adverse events after active treatments were not significantly different from those after placebo. At the recommended dose of 7.5 mg, zopiclone does not alter the elimination pharmacokinetics of the BZD anxiolytics diazepam (5mg) and lorazepam (1 mg), and neither is the elimination of zopiclone affected by these BZDs. Due to the rapid elimination of zopiclone, the increase in sedation seen after concurrent administration with BZDs is of short duration.

Determination of zolpidem and zopiclone in serum by capillary column gas chromatography

A gas chromatographic method using a short, high-resolution capillary column connected to a specific thermoionic detector and requiring a simple and short extraction step without evaporation was developed for the rapid and precise determination of two new hypnotics, zolpidem and zopiclone, in serum at concentrations greater than 5 ng/mL. The assay was linear between 5 and 200 ng/mL, with coefficients of intra- and interassay variation less than 5% for both. The method was validated and then used to analyze zolpidem serum concentrations in nine rabbits after oral administration of 0.5 mg/kg and zopiclone serum concentrations in six patients treated orally with a 7.5-g dose.

Hypnotics in the elderly. What cause for concern?

At any age hypnotic drug use can give rise to 3 major problems: unwanted effects on daytime mood and behaviour associated with drug consumption; rebound effects associated with drug withdrawal; and dependency associated with long term drug use. For 2 reasons elderly hypnotic users are both more vulnerable and more exposed to each of these problems. Firstly, age-related changes in pharmacodynamic and pharmacokinetic processes amplify the behavioural impact of many hypnotics; and secondly, age-related changes in the structure and quality of sleep tend to increase the demand for, and the long term use of, sedative hypnotic compounds in old age. The existence of physical illness, cognitive impairment, or daytime behaviour already compromised by normal aging processes further increases the likelihood of hypnotic drugs detrimentally affecting well-being in later life. These important causes for concern emphasise the need for 2 separate clinical responses: the need for greater circumspection in the choice and use of hypnotic drugs among elderly patients, and the need for a more broadly based clinical approach to the management of sleep problems in old age.

Actions of zopiclone and carbamazepine, alone and in combination, on human skilled performance in laboratory and clinical tests

1. Possible interactions of zopiclone and carbamazepine on human skilled performance were studied in a randomized, double-blind, crossover trial with 12 healthy young subjects. 2. Psychomotor performance (coordination, reactions, attention, cognition) and subjective effects (VAS) were measured and venous blood sampled before and 1.5, 3, 4.5 and 6 h after single oral doses of placebo, 7.5 mg of zopiclone and 600 mg of carbamazepine, which were given alone or combined. Clinical test for drunkenness (CTD) was done 2 and 5 h after drug intake. 3. Both zopiclone and carbamazepine, when administered alone, impaired performance on laboratory tests, the decrements being recorded 1.5 to 6 h after intake. In line with the plasma concentrations, the zopiclone effects peaked earlier (at 1.5 h) and lasted for a shorter time than those of carbamazepine. Zopiclone had a more pronounced effect on perceptual and cognitive functions (digit substitution) and it affected extraocular muscle tone (Maddox wing), whereas carbamazepine had stronger effects on attention. Additive pharmacodynamic actions were found in most tests after the combined treatment with zopiclone and carbamazepine. 4. CTD proved to be less sensitive than the laboratory tests in revealing drug-induced decrement of performance after administration of one agent alone. However, it revealed the combined decremental effects of zopiclone and carbamazepine. 5. When the drugs were given together, the absorption of drugs was retarded. Carbamazepine-10,11-epoxide levels were lower after intake of the drug combination than those measured after intake of carbamazepine alone. 6. The results suggest that the clinical tests developed to detect alcohol effects do not necessarily reveal drug-induced impairment of performance.

The excretion of zopiclone into breast milk

1. The excretion of zopiclone into breast milk was studied in 12 lactating women in the early postpartum period following the oral administration of a single zopiclone tablet (7.5 mg). 2. The milk/plasma AUC ratio of zopiclone was 0.51 +/- 0.09 (mean +/- s.d.). Individual mean milk/plasma concentration ratios of zopiclone showed significant interindividual variation (range 0.41-0.70). 3. A comparison of pharmacokinetic parameters in the postpartum women with those reported previously in non-pregnant women, showed significantly higher Cmax values in the lactating mothers; tmax occurred later in milk than in maternal plasma. 4. Assuming a daily milk intake of 0.15 l kg-1 and 100% absorption the average infant dose of zopiclone in milk would be 1.4% of the weight adjusted dose ingested by the mother.

Effects of zopiclone and temazepam on sleep, behaviour and mood during the day

Over a 3 week period the hypnotic effect of zopiclone 7.5 mg, temazepam 20 mg and placebo was investigated in a double-blind, cross-over study in 60 out-patients. The hypnotic effect, subdivided in the parameters sleep quality, latency of sleep onset and status after awaking, was scored daily by the patient after arising. The results showed that zopiclone 7.5 mg and temazepam 20 mg were almost equally effective. In sleep quality and latency of sleep onset, there appeared to be a non-significant trend favouring zopiclone. Both hypnotics differ significantly from placebo. Mood and behaviour during the day, as well as somatic symptoms and side-effects, were also scored daily and showed no significant differences between the treatments. The third week, which was a placebo week for all patients, showed a gradual improvement in sleep quality. It supports the case for not prescribing hypnotics for more than 2 weeks.

[Effects of zopiclone on sleep, daytime somnolence and nocturnal and daytime performance in healthy volunteers]

Ten healthy volunteers, aged 20 to 39, underwent 2 adaptation nights and 3 sessions of 2 consecutive experimental nights and days at 1 week intervals. In the 3 sessions, subjects received under double blind conditions either Zopiclone 3.75 mg or 7.5 mg or placebo, according to a latin-square design. On nights 1 and 2 of each session, subjects were continuously polygraphically monitored, except for a 45 min provoked wake episode 135 min after sleep onset on night 2. Sleep continuity and architecture were evaluated during night 1, degree of daytime somnolence during day 1 and residual effects during night 2 (0 h 00) and day 2 (8 h 00 and 12 h 00). Sleep continuity was not modified, except for a reduction of the number of night awakenings. NREM sleep stage 1 was reduced and stage 2 was increased (in duration but not in percentage) with Zopiclone 3.75 and 7.5 mg. NREM sleep stages 3 and 4 were increased with Zopiclone 3.75 mg only. REM sleep was reduced (in percentage only) with Zopiclone 3.75 and 7.5 mg. Daytime somnolence varied according to the time but not with the 3 different conditions. One performance test only (choice reaction time test) showed a significant impairment at 0 h 00 with Zopiclone 7.5 mg. From a subjective point of view, sleep quality was improved and night time awakening was reduced with Zopiclone 7.5 mg.

Zopiclone in insomniac shiftworkers. Evaluation of its hypnotic properties and its effects on mood and work performance

Fifty adult insomniac shiftworkers (47 males and 3 females) between the ages of 22 and 55 participated in this two-week, double-blind comparative study of the hypnotic properties and effects on mood and work performance of zopiclone 7.5 mg and placebo. All subjects took inactive medication on the first night of the study and then received either zopiclone or placebo for the following 13 nights according to randomization. Pre-study variables included a demographic profile, medical history, physical examination, laboratory data, profile of insomnia and work shift pattern description. A sleep questionnaire along with mood and work performance questionnaires were filled out on Days 1, 2, 4, 9 and 12 of the study; on Days 7 and 14, adverse events were recorded. After the first placebo night, subjects assigned to receive zopiclone showed significantly improved sleep induction; from the second night on, a distinct pharmacological effect over placebo was observed and maintained since statistically significant increases in quantitative sleep induction and sleep soundness (qualitative and quantitative) were noted during the course of zopiclone treatment. Active hypnotic treatment did not interfere with morning awakening and functioning, nor did it affect mood or work performance. Zopiclone treatment produced significantly more taste disturbance and drowsiness. In summary, zopiclone was shown to be an effective, fast-acting hypnotic which maintained its efficacy over a two-week period in our sample of insomniac shiftworkers and did not produce mood changes or influence work performance.

Comparative effects of zopiclone, triazolam and placebo on memory and psychomotor performance in healthy volunteers

This study evaluated the effects of acute doses of zopiclone (7.5 mg), triazolam (0.25 mg) and placebo on memory and psychomotor performance of 12 normal volunteers. The subjects received both drugs in a repeated measure, double-blind Latin square design. The tests (CFF, CRT, DSST, memory assessments) were performed before and 2 and 6 hr after treatment. Zopiclone and triazolam induced an anterograde amnesia affecting short-term and long-term memory which lasted less than 6 hr. No retrograde amnesia was observed. Two hr after drug intake of both hypnotics psychomotor performances were significantly altered compared with placebo. The subjects also felt more drowsy, dizzy, clumsy and tired, and less alert and energetic 2 hr after zopiclone and triazolam compared to placebo. There was no difference between the effects of the two hypnotics at the doses studied.

Zopiclone produces effects on human performance similar to flurazepam, lormetazepam and triazolam

The cognitive function and psychomotor performance of 10 healthy male volunteers were measured following single oral doses of: zopiclone (7.5 mg), flurazepam (15 mg), lormetazepam (1 mg), triazolam (0.25 mg) and placebo. The performance tests selected (stroop task, five choice serial reaction time, memory span, logical reasoning, mood and saccadic eye movement analysis) were thought to reflect aspects of normal daily activity. The tests demonstrated a clear reduction of performance for all active treatments. No drug emerged as the most potent sedative overall, as each of the tests was affected to a different degree by each drug. Drug effects were not qualitatively different between active treatments so that zopiclone was indistinguishable from the three benzodiazepines with which it was compared.

Hypnotics. Their place in therapeutics

Sleep disturbance has become a subject of serious study only over the past few years, but even so there is already an increasing awareness of the nature of insomnia and a greater understanding of the role which hypnotics should play in clinical medicine. An hypnotic may be used to shorten sleep onset when there is difficulty in falling asleep, to reduce nocturnal wakefulness, or to provide an anxiolytic effect during the next day when insomnia is accompanied by a marked element of anxiety. The purpose of an hypnotic is to meet one or more of these clinical problems; to ensure that the patient is given the most useful medication, consideration must be given to duration of activity. This depends on the absorption, distribution and elimination characteristics of the drug. It is now appreciated that the most appropriate use of hypnotics is in the individual with insomnia of recent origin. An hypnotic with the most relevant pharmacokinetic profile should be used for the shortest period of time and then only as required, while low doses will ensure freedom from adverse effects. The place of hypnotics in chronic insomnia remains less certain. Their careful use may well be of benefit, though it must be part of a well defined clinical strategy. Assessment of the patient is essential to identify any specific conditions which would impair sleep.