Rebound insomnia and elimination half-life: assessment of individual subject response

Alliance for Sleep Clinical Practice Guideline on Switching or Deprescribing Hypnotic Medications for Insomnia

Determining the most effective insomnia medication for patients may require therapeutic trials of different medications. In addition, medication side effects, interactions with co-administered medications, and declining therapeutic efficacy can necessitate switching between different insomnia medications or deprescribing altogether. Currently, little guidance exists regarding the safest and most effective way to transition from one medication to another. Thus, we developed evidence-based guidelines to inform clinicians regarding best practices when deprescribing or transitioning between insomnia medications. Five U.S.-based sleep experts reviewed the literature involving insomnia medication deprescribing, tapering, and switching and rated the quality of evidence. They used this evidence to generate recommendations through discussion and consensus. When switching or discontinuing insomnia medications, we recommend benzodiazepine hypnotic drugs be tapered while additional CBT-I is provided. For Z-drugs zolpidem and eszopiclone (and not zaleplon), especially when prescribed at supratherapeutic doses, tapering is recommended with a 1–2-day delay in administration of the next insomnia therapy when applicable. There is no need to taper DORAs, doxepin, and ramelteon. Lastly, off-label antidepressants and antipsychotics used to treat insomnia should be gradually reduced when discontinuing. In general, offering individuals a rationale for deprescribing or switching and involving them in the decision-making process can facilitate the change and enhance treatment success.

Pharmacotherapeutic management of insomnia and effects on sleep processes, neural plasticity, and brain systems modulating stress: A narrative review

Introduction

Insomnia is a stress-related sleep disorder, may favor a state of allostatic overload impairing brain neuroplasticity, stress immune and endocrine pathways, and may contribute to mental and physical disorders. In this framework, assessing and targeting insomnia is of importance.

Aim

Since maladaptive neuroplasticity and allostatic overload are hypothesized to be related to GABAergic alterations, compounds targeting GABA may play a key role. Accordingly, the aim of this review was to discuss the effect of GABAA receptor agonists, short-medium acting hypnotic benzodiazepines and the so called Z-drugs, at a molecular level.

Method

Literature searches were done according to PRISMA guidelines. Several combinations of terms were used such as “hypnotic benzodiazepines” or “brotizolam,” or “lormetazepam” or “temazepam” or “triazolam” or “zolpidem” or “zopiclone” or “zaleplon” or “eszopiclone” and “insomnia” and “effects on sleep” and “effect on brain plasticity” and “effect on stress system”. Given the complexity and heterogeneity of existing literature, we ended up with a narrative review.

Results

Among short-medium acting compounds, triazolam has been the most studied and may regulate the stress system at central and peripheral levels. Among Z-drugs eszopiclone may regulate the stress system. Some compounds may produce more “physiological” sleep such as brotizolam, triazolam, and eszopiclone and probably may not impair sleep processes and related neural plasticity. In particular, triazolam, eszopiclone, and zaleplon studied in vivo in animal models did not alter neuroplasticity.

Conclusion

Current models of insomnia may lead us to revise the way in which we use hypnotic compounds in clinical practice. Specifically, compounds should target sleep processes, the stress system, and sustain neural plasticity. In this framework, among the short/medium acting hypnotic benzodiazepines, triazolam has been the most studied compound while among the Z-drugs eszopiclone has demonstrated interesting effects. Both offer potential new insight for treating insomnia.

Benzodiazepines and Related Sedatives

Benzodiazepine and related sedative use has been increasing. There has been a growing number of unregulated novel psychoactive substances, including designer benzodiazepines. Benzodiazepines have neurobiological and pharmacologic properties that result in a high potential for misuse and physical dependence. Options for discontinuing long-term benzodiazepine use include an outpatient benzodiazepine taper or inpatient withdrawal management at a hospital or detoxification facility. The quality of evidence on medications for benzodiazepine discontinuation is overall low, whereas cognitive behavioral therapy has shown the most benefit in terms of behavioral treatments. Benzodiazepines may also have significant adverse effects, increasing the risk of overdose and death.

Reintroduction of quazepam: an update on comparative hypnotic and adverse effects

Insomnia is a prevalent disorder that affects over one-third of the U.S. population to varying degrees and is highly disruptive towards quality of life. Pharmacological treatments for insomnia include benzodiazepines (BZs) and the non-BZ 'Z-drugs' (zolpidem, zaleplon, eszopiclone, zopiclone), which are amongst the most widely prescribed medications. Yet, these agents can produce adverse effects such as tolerance to the hypnotic effect, rebound insomnia, next-day residual drowsiness, as well as amnesia and complex behaviours such as sleep-walking, sleep-eating and sleep-driving. Quazepam, one of the five BZ approved for treatment of insomnia, was recently relaunched to the U.S. market in 2016 and is distinguished amongst hypnotic BZ by unique pharmacological characteristics including selectivity for sleep-promoting α1-subunit containing γ-aminobutyric acid (GABA-A) receptors and a significantly lower relative receptor binding affinity. These features likely drive the decreased rate of adverse events seen clinically with quazepam, such as tolerance, rebound insomnia and amnesic behaviours, compared with other BZ. Given the recent reintroduction of quazepam as a pharmacotherapeutic option, and the lack of head-to-head comparative trials against newer agents, the purpose of this review is to provide an update on distinguishing features of quazepam with regard to its pharmacology, pharmacokinetics, sleep efficacy and potential adverse effects compared to other agents used for insomnia.

Dependence, withdrawal and rebound of CNS drugs: an update and regulatory considerations for new drugs development

The purpose of this article is to describe dependence and withdrawal phenomena related to CNS drugs discontinuation and to clarify issues related to the evaluation of clinical drug withdrawal and rebound as they relate to safety in new drug development. The article presents current understanding and definitions of drug dependence and withdrawal which are also relevant and important features of addiction, though not the same. Addiction, called substance use disorder in DSM-5, affects an individual’s brain and behaviour, represents uncontrollable drug abuse and inability to stop taking a drug regardless of the harm it causes. Characteristic withdrawal syndromes following abrupt discontinuation of CNS-active drugs from numerous drug classes are described. These include drugs both scheduled and non-scheduled in the Controlled Substances Act, which categorizes drugs in five schedules based on their relative abuse potentials and dependence liabilities and for regulatory purposes. Schedules 1 and 2 contain drugs identified as those with the highest abuse potential and strictest regulations. Less recognized aspects of drug withdrawal, such as rebound and protracted withdrawal syndromes for several drug classes are also addressed. Part I presents relevant definitions and describes clinical withdrawal and dependence phenomena. Part II reviews known withdrawal syndromes for the different drug classes, Part III describes rebound and Part IV describes protracted withdrawal syndromes. To our knowledge, this is the first compilation of withdrawal syndromes for CNS drugs. Part V provides details of evaluation of dependence and withdrawal in the clinical trials for CNS drugs, which includes general design recommendations, and several tools, such as withdrawal questionnaires and multiple scales that are helpful in the systematic evaluation of withdrawal. The limitations of different aspects of this method of dependence and withdrawal evaluation are also discussed.

Challenges of a mechanistic feedback model describing nicotinic acid-induced changes in non-esterified fatty acids in rats

Previously, we developed a feedback model to describe the tolerance and oscillatory rebound of non-esterified fatty acid (NEFA) plasma concentrations in male Sprague Dawley rats after intravenous infusions of nicotinic acid (NiAc). This study challenges that model, using the following regimens of intravenous and oral NiAc dosing in male Sprague Dawley rats (n = 95) to create different patterns of exposure: (A) 30 min infusion at 0, 1, 5 or 20 μmol kg(-1) body weight; (B) 300 min infusion at 0, 5, 10 or 51 μmol kg(-1); (C) 30 min infusion at 5 μmol kg(-1), followed by a stepwise decrease in rate every 10 min for 180 min; (D) 30 min infusion at 5 μmol kg(-1), followed by a stepwise decrease in rate every 10 min for 180 min and another 30 min infusion at 5 μmol kg(-1) from 210 to 240 min; (E) an oral dose of 0, 24.4, 81.2 or 812 μmol kg(-1). Serial arterial blood samples were taken for measurement of plasma NiAc and NEFA concentrations. The gradual decrease in infusion rate in (C) and (D) were also designed to test the hypothesis that a gradual reduction in NiAc plasma concentration may be expected to reduce or prevent rebound. The absorption of NiAc was described by parallel linear and non-linear processes and the disposition of NiAc by a two-compartment model with endogenous turnover rate and two parallel capacity-limited elimination processes. NEFA (R) turnover, which was driven by the plasma concentration of NiAc via an inhibitory drug-mechanism function acting on NEFA formation, was described by a feedback model with a moderator distributed over a series of transit compartments, where the first compartment (M 1) inhibited the formation of R and the last compartment (M N ) stimulated the loss of R. All processes regulating the plasma NEFA concentration were assumed to be captured by the moderator function. Data were analyzed using non-linear mixed effects modeling (NONMEM). The potency IC 50 of NiAc was 68 nmol L(-1), the fractional turnover rate k out 0.27 L mmol(-1) min(-1), and the turnover rate of moderator k tol 0.023 min(-1). The lower physiological limit of NEFA, which was modeled as a NiAc-independent release (k cap ) of NEFA into plasma, was estimated to 0.023 mmol L(-1) min(-1). The parameter estimates derived in this study were consistent with our previous estimates, suggesting that the model may be used for prediction of the NEFA response time-course following different modes and routes administration of NiAc or NiAc analogues. In order to avoid NiAc-induced NEFA rebound, a slow decline in the NiAc exposure pattern is needed at or below IC (50).

Sedation for critically ill or injured adults in the intensive care unit: a shifting paradigm

As most critically ill or injured patients will require some degree of sedation, the goal of this paper was to comprehensively review the literature associated with use of sedative agents in the intensive care unit (ICU). The first and selected latter portions of this article present a narrative overview of the shifting paradigm in ICU sedation practices, indications for uninterrupted or prolonged ICU sedation, and the pharmacology of sedative agents. In the second portion, we conducted a structured, although not entirely systematic, review of the available evidence associated with use of alternative sedative agents in critically ill or injured adults. Data sources for this review were derived by searching OVID MEDLINE and PubMed from their first available date until May 2012 for relevant randomized controlled trials (RCTs), systematic reviews and/or meta-analyses and economic evaluations. Advances in the technology of mechanical ventilation have permitted clinicians to limit the use of sedation among the critically ill through daily sedative interruptions or other means. These practices have been reported to result in improved mortality, a decreased length of ICU and hospital stay and a lower risk of drug-associated delirium. However, in some cases, prolonged or uninterrupted sedation may still be indicated, such as when patients develop intracranial hypertension following traumatic brain injury. The pharmacokinetics of sedative agents have clinical importance and may be altered by critical illness or injury, co-morbid conditions and/or drug-drug interactions. Although use of validated sedation scales to monitor depth of sedation is likely to reduce adverse events, they have no utility for patients receiving neuromuscular receptor blocking agents. Depth of sedation monitoring devices such as the Bispectral Index (BIS©) also have limitations. Among existing RCTs, no sedative agent has been reported to improve the risk of mortality among the critically ill or injured. Moreover, although propofol may be associated with a shorter time to tracheal extubation and recovery from sedation than midazolam, the risk of hypertriglyceridaemia and hypotension is higher with propofol. Despite dexmedetomidine being linked with a lower risk of drug-associated delirium than alternative sedative agents, this drug increases risk of bradycardia and hypotension. Among adults with severe traumatic brain injury, there are insufficient data to suggest that any single sedative agent decreases the risk of subsequent poor neurological outcomes or mortality. The lack of examination of confounders, including the type of healthcare system in which the investigation was conducted, is a major limitation of existing pharmacoeconomic analyses, which likely limits generalizability of their results.

Quantitative analysis of rate and extent of tolerance of biomarkers: application to nicotinic acid-induced changes in non-esterified fatty acids in rats

In this paper we quantitatively evaluate two feedback systems with a focus on rate and extent of tolerance and rebound development. In the two feedback systems, the regulation of turnover of response is governed by one or several moderators. In the basic system, one single moderator inhibits the formation of response. This system has been applied to cortisol secretion and serotonin reuptake inhibition. The basic system has been extended to adequately describe nicotinic acid (NiAc)-induced changes in non-esterified fatty acids (NEFA). In the extended system, the feedback is described by a cascade of moderators where the first inhibits formation of response and the last stimulates loss of response. The objectives of this paper were to analyze these systems from a mathematical/analytical and quantitative point of view and to present simulations with different parameter settings and dosing regimens in order to highlight the intrinsic behaviour of these systems and to present expressions and graphs that are applicable for quantification of rate and extent of tolerance and rebound. The dynamics of the moderators (k(tol)) compared to the dynamics of the response (k(out)), was shown to be important for the behaviour of both systems. For instance, slow dynamics of the moderator compared to the response (k(tol)<<k(out)), resulted in overshoot and pronounced rebound. The extent of tolerance was studied over time at a single constant drug concentration and at steady state for different drug concentrations and was found to be largest at drug concentrations close to IC(50). An upper limit for the response could be identified and included in the quantification of extent of rebound. Especially, for the extended system, the duration of exposure was an important factor affecting size of rebound. The rate of tolerance development was addressed by quantitatively estimating the time to steady state for the two systems, in which the value of k(tol) and the length of the cascade were critical.

Determination of the main risk factors for benzodiazepine dependence using a multivariate and multidimensional approach

The aim of this study was to identify risk factors for benzodiazepine (BZD) dependence, such as sociodemographic variables, characteristics of BZD use, and psychiatric parameters, which to date have been found to relate inconsistently to indicators of BZD dependence such as chronic BZD use and BZD withdrawal symptoms. The Benzodiazepine Dependence Self-Report Questionnaire (Bendep-SRQ), Schedules for Clinical Assessment in Neuropsychiatry (SCAN), and Symptom Checklist-90 (SCL-90) were administered to 599 outpatients using BZDs. Regression analyses were conducted using BZD dependence diagnoses and severity scales as dependent variables. BZD dependence diagnoses were only predicted by being a self-help patient and long BZD elimination half-life (for only the DSM-III-R). The main predictors of BZD dependence severity, as measured by the ICD-10, DSM-III-R scales, and Bendep-SRQ Rasch scales, were in decreasing order: (1) being a self-help patient; (2) higher BZD dose, longer duration of BZD use, younger age; and (3) non-native cultural origin, lower level of education, being in outpatient treatment for alcohol and/or drug dependence, and the interaction of BZD dose with duration of BZD use. We conclude that a limited number of recognizable risk factors appear to predict the severity of BZD dependence. Additional administration of a specific BZD dependence instrument is recommended to confirm suspected BZD dependence and guide further clinical decision-making.

Independent sleep EEG slow-wave and spindle band dynamics associated with 4 weeks of continuous application of short-half-life hypnotics in healthy subjects

OBJECTIVES

Habituation and adverse withdrawal reactions after prolonged medication with benzodiazepine (BZ) hypnotics are believed to play a role in dose escalation and the development of dependence.

METHODS

In the current sleep EEG study in 43 healthy male subjects, the known property of BZ- and similar hypnotics to change the NREM sleep EEG spectrum is utilized for a detailed quantitative analysis across 4 weeks of continuous medication and a subsequent two-week withdrawal period. The BZ hypnotic triazolam and the non-BZ hypnotics zopiclone and zolpidem, differing in pharmacological properties and reported adverse effects, were examined in parallel to a placebo group.

RESULTS

Reliably occurring spectral effects in the sleep stage 2 EEG were found in the 3 frequency bands 0.8-5 Hz, 5-10 Hz and 10-15 Hz. All 3 hypnotics showed the typical 'benzodiazepine signature', a 10-15 Hz increase and lower-frequency (<10 Hz) suppression relative to the preceding drug-free night. However, these effects developed differently across the first medication night, across the 4 medication weeks and after withdrawal: While the 5-10 Hz effect covaried with the blood presence of the drugs as estimated from the known plasma half-lifes, showed habituation and a rebound after withdrawal, the 10-15 Hz power increased across medication days and showed no rebound. Effects in the 0.8-5 Hz band in the first medication night correlated with the decrease of sleep efficiency at later withdrawal for triazolam and zolpidem.

The dependence potential of short half-life benzodiazepines: a meta-analysis

OBJECTIVES

The dependence potential of benzodiazepine medications is now widely recognized, but uncertainty exists as to whether use of short half-life vs long half-life drugs results in greater dependence. The present study reports a meta-analysis of the extant research to evaluate the dependence potential of different types of benzodiazepines.

METHOD

Seven studies were found that specifically compared long half-life and short half-life benzodiazepines and allowed statistical comparison by their homogeneous dependent variables. Drugs in these studies were used as daytime sedatives.

RESULTS

Substantial evidence was found for differential effects of short vs long half-life drugs at withdrawal. In all studies, dropouts were higher among short half-life subjects. In the random-assignment short-term use studies, Hamilton Anxiety Scale scores showed higher incidence of rebound among subjects who used the short half-life drugs.

CONCLUSIONS

The present meta-analysis confirms clinical impressions of the greater dependence potential of short vs long half-life benzodiazepines. Doctors, patients, and policymakers need to be informed so as to avoid harm to the public health through unintended drug dependence.

A double-blind, comparative study of zolpidem and placebo in the treatment of insomnia in elderly psychiatric in-patients

The efficacy and tolerability of the imidazopyridine hypnotic, zolpidem, were investigated in 119 elderly psychiatric in-patients complaining of insomnia in a double-blind, parallel-group, placebo-controlled trial. After a 7-day placebo washout period, patients were randomized to receive 10 or 20 mg/day zolpidem, or placebo for 21 days; thereafter, all patients received placebo for 7 days. Sleep was assessed by patient observation on days 0, 1, 7, 14, 21, 22 and 28. Compared with placebo, 20 mg/day zolpidem significantly improved total duration of sleep between day 0 and day 21, and this was maintained at day 28. After 10 or 20 mg/day zolpidem, there was also a trend towards improvement in all other sleep parameters, which remained above baseline at day 28. Zolpidem was well tolerated with no withdrawal symptoms during the second 7-day placebo treatment period. Daytime drowsiness was reported in three patients receiving 20 mg/day zolpidem and in one receiving 10 mg/day zolpidem, but there was no significant increase in daytime drowsiness between days 0 and 21. Ataxia occurred in two, one and one patient, respectively, treated with 20 mg/day zolpidem, 10 mg/day zolpidem and placebo. The incidences of other adverse events or effects on clinical and laboratory parameters were minimal and similar in all three treatment groups. It is concluded that, in elderly psychiatric patients, 10 mg/day zolpidem can be used to treat insomnia and can be safely added to concomitant psychotropic treatment without inducing daytime drowsiness.

[Benefits and risks of hypnotics]

Rationalisation of the war of hypnotics has recently been under discussion in France: a review of the benefits and risks of these substances may therefore be useful. Chronic insomnia is a result of multiple factors, among which individual characteristics of the personality play an important role. Hypnotic treatment is symptomatic; its beneficial influence on sleep progressively vanishes in few weeks, while some negative residual effects on daytime functioning (mood, alertness, performance, memory impairment) may persist. The main problems posed by hypnotic treatment with benzodiazepines are related to tolerance effects during the treatment period and to rebound insomnia and withdrawal phenomena after discontinuation. Practical issues for the treatment of insomnia, based on international consensus, are presented.

Adverse effects of benzodiazepines

The growing realisation that the benzodiazepines have potential for causing serious harm has caused concern due to their wide and common use. This paper is a review of the adverse effects of benzodiazepines, and concentrates on four areas of particular concern: drug dependence with the consequent withdrawal symptoms; psychological effects while on the drugs; use by the elderly; and tolerance to the drug effects. Although the phenomenon of a benzodiazepine withdrawal syndrome is generally accepted, there is still controversy over the frequency amongst users. A number of major studies are reviewed here, and the main methodological issues are discussed. These include definition of the withdrawal symptoms, selection of subjects, and use of double-blind, placebo-controlled conditions. The studies investigating psychological impairment with benzodiazepine use deal mainly with motor performance and co-ordination, although there is a large group of studies looking at the effect of the drugs on memory. Although the studies reviewed make a considerable contribution to the understanding of the effects of benzodiazepines, they focus on physiological and specific psychological variables, rather than more global measures of functioning and behaviour. It is suggested here that this emphasis needs to change in order to obtain a clearer picture of how benzodiazepines affect quality of life. Future studies should also be prospective in design, and include clear criteria for the selection of subjects and for the definition of withdrawal symptoms.

Midazolam and nitrazepam in the maternity ward: milk concentrations and clinical effects

1. In a randomized study of 22 patients in a maternity ward, the residual concentrations of two hypnotics, midazolam 15 mg p.o. and nitrazepam 5 mg p.o., in early breast milk and plasma were measured 7 h after intake on day 2 to day 6 postpartum. Milk pH, milk fat and binding to plasma proteins were also investigated. Sleep variables were scored on questionnaires. 2. No measurable (less than 10 nmol l-1) concentrations of drug in milk were found in the group receiving 15 mg midazolam at night, either after the first night or after the fifth night. Additional investigations in two mothers demonstrated that midazolam and its hydroxymetabolite disappeared rapidly from milk with undetectable levels after 4 h. The mean (s.d.) milk to plasma ratio for midazolam was 0.15 (0.06) in six paired samples. It may be assumed that practically no midazolam is transferred via early milk to the baby if the baby is nursed more than 4 h after tablet intake. 3. Milk nitrazepam concentrations increased significantly from the first (30 nmol l-1) to the fifth morning (48 nmol l-1) in the group receiving 5 mg nitrazepam at night. The mean (s.d.) milk to plasma ratio of nitrazepam after 7 h was 0.27 (0.06) in 32 paired samples, and did not vary from day 1 to day 5. Plasma protein binding of nitrazepam in puerperal women was found to be lower than that in plasma of healthy controls. The average amount of nitrazepam received by the breast-fed baby in the morning was calculated to increase from 1 to 1.5 micrograms 100 ml-1 breast milk, from days 1 to 5. In the mothers nitrazepam was associated with better hypnotic effect, but a higher incidence of complaints than midazolam. 4. Milk pH, assuming anaerobic conditions, was found in 10 women to average 6.91 +/- 0.09 (s.d.) on days 2-6 postpartum, which is less than previously reported. 5. It is concluded that both hypnotics may be used safely for a few days in the maternity ward. However, possible long-term effects in the suckling infant of small doses of benzodiazepines ingested with breast milk remain to be investigated.

Insomnia

Because sleep needs vary from person to person, insomnia is defined as the chronic inability to obtain the amount of sleep needed for optimal functioning and well-being. Insomnia, which is a symptom rather than a disease, can be classified into three main etiologic groups: insomnias related to other mental disorders (for example, depression and anxiety), insomnias related to known organic factors (for example, sleep apnea and "nonrestorative" sleep), and primary insomnia (for example, learned psychophysiologic insomnias and insomnia complaints without objective findings). The treatment for insomnia often involves a combination of pharmacotherapy, behavioral and short-term psychotherapy, and sleep hygiene guidelines. Sleep disorders centers can provide specialized knowledge and techniques for patients with severe chronic insomnia.

Appropriately treating insomnia with triazolam

Insomnia is a problem that extends beyond the nighttime. People who experience sleep disturbances complain that they stay awake for a long time before they fall asleep. They may wake up several times during the night and cannot return to sleep and/or they wake up early in the morning. As a result, they feel sleepy during the day and are less alert. Various forms of insomnia are described that require--as much as possible--an individualized treatment approach. Besides sleeping hygiene, benzodiazepines certainly occupy a place in the treatment of insomnia. Triazolam, a triazolobenzodiazepine, closely approaches the characteristics of an ideal hypnotic: pharmacological activity at the level of the receptors, moderate absorption, short-acting, and rapid elimination. It is effective and safe if prescribed correctly and at the appropriate dosage.

Evaluation of long-term triazolam use in an ambulatory Veterans Administration Medical Center population

Triazolam is indicated for the short-term treatment of insomnia. To determine how it was being prescribed and used, we examined triazolam use in patients who had received the drug for greater than six weeks. We reviewed medical charts of 72 adult male patients from an ambulatory Veterans Administration population who had received a 30-day triazolam prescription with at least one refill. Results showed that although prescribed daily doses of triazolam were generally appropriate for the age of the patient being treated, the average length of therapy was 6.2 months. Seventy-five percent of the prescriptions had been written for a one-month supply with five refills. Neither prescriber specialty nor level of training was significantly related to length of therapy. Thirty-nine of the patients (54 percent) were available for a telephone interview to determine how the drug was actually being used and the adverse effects profile. Over 60 percent claimed to be taking the drug every night, 95 percent at the dose prescribed. Sixty-seven percent of the patients taking triazolam nightly reportedly did not sleep as well if they tried a night without the drug. Apart from effects on sleep, dizziness and confusion were the most commonly reported adverse effects. As a result of this study, automatic stop orders on discharge were implemented to limit triazolam therapy to inpatient stays. Physicians must evaluate the need for continued hypnotic therapy so that a longer-acting agent like flurazepam may be used if chronic medication is necessary.

Quazepam. A preliminary review of its pharmacodynamic and pharmacokinetic properties, and therapeutic efficacy in insomnia

Quazepam is a trifluoroethyl benzodiazepine hypnotic with a half-life of 27 to 41 hours, which has been shown to induce and maintain sleep in the short to long term (up to 4 weeks) treatment of patients with chronic or transient insomnia. Although its hypnotic efficacy has been well characterised against placebo, there are few clinical studies in comparison with established hypnotics, particularly over long term administration. However, preliminary evidence suggests that quazepam 15 to 30 mg is as effective as flurazepam and triazolam in usual therapeutic doses, and causes minimal rebound insomnia following its withdrawal, unlike rapidly eliminated benzodiazepines such as triazolam. The lack of rebound phenomena is likely to be attributable to the 'carryover' effects occurring after discontinuation of quazepam, which has pharmacologically active metabolites with half-lives of elimination similar to or longer than that of the parent drug. Probably because of the long half-lives of quazepam's metabolites, daytime sedation, fatigue and lethargy are the most frequently reported side effects. These side effects are most intense with the 30 mg dose and least with the 7.5mg dose, which has not been studied extensively. Hence, quazepam is an effective hypnotic which may be particularly suitable for short or medium term use in patients in whom withdrawal effects or rebound insomnia may be especially bothersome. Further definition of certain characteristics of its profile--such as its long term use and potential for development of tolerance or dependence, effects on psychomotor skills, efficacy of the 7.5mg dose, and suitability in elderly patients and patients with chronic organic diseases--will assist in more clearly defining its ultimate place in therapy.

Efficacy without tolerance or rebound insomnia for midazolam and temazepam after use for one to three months

Midazolam (15 mg) was compared with temazepam (30 mg) in a randomized, double-blind, parallel group study. An initial screening period was followed by 3 days of placebo baseline, 4 to 12 weeks of nightly oral use of the medication and a 4-day placebo withdrawal period. One hundred seventy-five patients with chronic insomnia participated in this multicenter outpatient study. Because the elimination half-life of midazolam, a new trizolobenzodiazepine hypnotic, is short (1.3-2.2 hr) compared to temazepam's (12-16 hr), more problems with tolerance and rebound insomnia were expected to occur. Hypnotic efficacy (increased total sleep time, decreased wake time, and decreased sleep latency) was demonstrated for both medications over the entire 3-month period without the development of tolerance. In fact, if anything, efficacy increased with time on medication, suggesting possible facilitation or "inverse tolerance" effect. On withdrawal, sleep was improved compared with baseline, suggesting partial resolution of the insomniac condition rather than rebound insomnia. These effects were both statistically and clinically significant for midazolam, with 16% to 50% improvement in sleep measures. The results of this study suggest that patients with chronic insomnia may benefit from 30 to 90 days of treatment. A three-factor model that separates pharmacologic from behavioral and psychologic effects of hypnotics was proposed to explain these results in part.

The clinical use of hypnotics: indications for use and the need for a variety of hypnotics

Insomnia may be categorized as difficulty falling asleep, frequent awakening, early awakenings or a combination of each. The ideal hypnotic must promote rapid sleep onset and maintain sleep throughout the night while allowing the patient to awake refreshed the following day. Several benzodiazepines, with differing pharmacokinetic and pharmacodynamic profiles are presently available. All are clinically effective and not only elimination half-life but also dosage prescribed and pattern of distribution are important factors for determining treatment response. Hypnotics have been divided into those with long elimination half-lives (e.g. nitrazepam, flunitrazepam, flurazepam), those with intermediately long half-lives (brotizolam, loprazolam, lormetazepam, temazepam) and those with short half-lives (midazolam and triazolam). Carry-over effects into the morning such as excessive daytime sleepiness or drowsiness are related to drug half-life, dosage and pattern of distribution. In equipotent dosages most controlled clinical trials have found no significant differences between the various benzodiazepine hypnotics. Nevertheless, clinicians in general tend to use long half-life benzodiazepines in patients who have difficulties maintaining sleep and short half-life benzodiazepines for treating sleep onset insomnia. Intermediately long half-life, benzodiazepines are used for both indications and most clinicians feel that the choice of hypnotic should not only be influenced by elimination half-life or the dosage used, but by individual patient preference. Hypnotics should be used for only short periods of time and in those patients for whom a more chronic use is indicated, they should be used only on an intermittent basis.

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.