Pharmacodynamic correlates of modified absorption: studies with lormetazepam

Modulation of rate of onset and intensity of drug effects reduces abuse potential in healthy males

Low, medium, and high doses of flunitrazepam were tested in three independent randomized, double-blind, balanced cross-over, placebo-controlled trials to study the influence of rate of onset of effects and dose administered on its acute effects. Three groups of 12 healthy male volunteers received six oral doses of placebo or flunitrazepam in slow and fast onset conditions as follows: six capsules of 0.16 mg (slow) and a single capsule of 0.8 mg (fast) in the low dose trial; six 0.25 mg (slow) and a single 1.25 mg (fast) capsules for medium dose; and six 0.4 mg (slow) and a single 2 mg (fast) capsule for high dose. At each dose level, slow or fast increasing flunitrazepam plasma concentrations lead to similar peak levels, but induced differential subjective and behavioral effects. In addition to objective and subjective sedation, flunitrazepam induced some pleasurable feelings, which were more intense in the fast than in the slow conditions. At the highest dose, unpleasant sedative effects surmounted positive effects, while at the lowest dose pleasurable effects were of low intensity. At the medium dose, the balance between pleasurable and unpleasant feelings resulted in euphorigenic effects, which were evident in the fast condition but were blunted in the slow condition.

Drug treatment of patients with insomnia and excessive daytime sleepiness: pharmacokinetic considerations

Insomnia and excessive daytime sleepiness (EDS) are frequently observed conditions in the general public. A national survey in the USA in 1979 indicated that 35% of American adults experience insomnia in the course of a year. The prevalence of EDS varies depending on the survey (0.3 to 13.3%), but a recent study stated that 2.4% of individuals reported that they continually fell asleep at work. These problems are often long term and negatively affect the individuals' quality of life. People with these sleep problems often have difficulties maintaining high levels of productivity at work or pursuing their daily activities; individuals with insomnia lack the feeling of being rested or refreshed in the morning and EDS is unavoidable in most cases. Behavioural therapy has been shown to be effective for many people affected with insomnia and EDS. However, pharmacological treatments using hypnosedatives and central nervous system (CNS) stimulants are usually necessary, and effective, for those with more severe cases. These compounds have thus been widely prescribed in clinical practice (e.g., 2.6% of all adults surveyed used medically prescribed hypnosedatives and 4.5% used over-the-counter drugs to promote sleep). The onset and duration of action of these hypnosedatives and CNS stimulant drugs are important factors to be considered when prescribing these compounds. These factors primarily depend on physicochemical properties (lipid solubility and protein binding), as well as the pharmacokinetic profile (absorption, distribution, elimination and clearance) of the compounds. Significant differences in profile exist amongst hypnosedatives and CNS stimulants, and these differences may account for the observed variations in clinical action and adverse effects during and after treatment. In this review, we will introduce recently obtained knowledge of the pharmacokinetics of hypnosedatives and CNS stimulants and their applications for patients affected with insomnia and EDS.

An assessment of short-acting hypnotics

Insomnia, the experience of poor quality or quantity of sleep, is a very common complaint. Approximately 65 million adults (36% of the American population) complain of poor sleep, and of this group, 25% have insomnia on a chronic basis. These chronic insomniacs not only report higher rates of difficulty with concentration, memory and the ability to cope with minor irritations but also have 2.5 times more fatigue-related automobile accidents than do good sleepers. Despite its ubiquity, insomnia is often either untreated or inadequately treated. Short-acting hypnotics are advocated for transient insomnia, which lasts less than 3 weeks, and in patients with chronic insomnia as an adjunctive treatment where nonpharmacological treatment is not sufficient to alleviate insomnia and the related daytime detrimental effects. The putative adverse effects of hypnotics must be weighted against the severe health effects caused by continued sleep impairment. If hypnotic agents are used, they should be taken nightly only for brief use, or intermittently in longer term use. Benzodiazepines, zolpidem and zopiclone (in countries where the latter is available) remain the recommended hypnotic agents, although in the past few years there has been much criticism in lay magazines and on television about the use of benzodiazepines. However, this review of the efficacy and tolerability data of the short-acting hypnotics suggests that triazolam is comparable with other short-acting hypnotics at equipotent doses while taking into consideration that for every hypnotic, different study populations display different degrees of efficacy. In addition, contrary to previous suggestions that such adverse effects are rebound insomnia and anterograde amnesia are unique to triazolam, hypnotically equivalent doses of tirazolam have not been shown to produce these effects more frequently than other short-acting hypnotics. The newer nonbenzodiazepine hypnotics seem to be equally efficacious as the short-acting benzodiazepines; whether they will truly have a better adverse effect profile will be determined as more clinical experience accumulates. Despite the availability, relative safety and efficacy of these newer hypnotic agents, they should not be perceived as the sole treatment for insomnia and should be used in conjunction with nonpharmacological techniques (such as adherence to good sleep hygiene, sleep restriction, stimulus control and biofeedback therapy).

Pharmacological treatment of insomnia

Insomnia is a widespread condition which affects approximately one-third of the general population. It is especially prevalent in the elderly. The treatment modalities of insomnia are varied and include nonpharmacological and pharmacological techniques. Insomnia is a symptom of an underlying condition. Before starting treatment, it is imperative to carefully assess the possible causes of insomnia, since the aetiology of the insomnia determines the treatment. Pharmacotherapy is indicated in transient insomnia which occurs in otherwise healthy, normal sleepers, and in the treatment of intermittent insomnia in the elderly. Pharmacotherapy is not indicated in chronic insomnia, except perhaps on an intermittent basis and as adjunctive treatment. If adjunctive pharmacotherapy is to be used in chronic insomnia, the possibility of a primary sleep disorder must be ruled out prior to the use of a sedative hypnotic. When using sedative hypnotic agents, the lowest possible dose should be used for the shortest possible time. Special care should be exercised when treating the elderly, because altered pharmacokinetics in this age group may impair tolerability. Benzodiazepines remain the recommended hypnotic agents, although newer, non-benzodiazepine agents may also be utilised. Despite the relative safety of benzodiazepines, the most common adverse effects include residual daytime sleepiness, rebound insomnia and anterograde amnesia. Short-acting benzodiazepines are more commonly associated with rebound insomnia and withdrawal symptoms, whereas the long acting benzodiazepines are more likely to produce residual daytime sleepiness. Anterograde amnesia may be seen with all benzodiazepines. Use of alcohol for its sedative properties, and over-the-counter preparations, are not recommended for the treatment of insomnia.

Repeated dose effects of lormetazepam and flurazepam upon driving performance

The residual effects of lormetazepam 1 mg and 2 mg in soft gelatine capsules on driving performance were assessed and compared to those of flurazepam 30 mg, which is also a powerful hypnotic, but possesses a far less favourable pharmacokinetic profile with a long-acting sedative metabolite. Driving performance was tested 10 to 11 h and 16 to 17 h post administration, after 2 days on placebo (baseline), and 2, 4 and 7 days of drug treatment (active), and after 1 and 3 days following the resumption of placebo (washout). The driving test consisted of operating an instrumented motor-vehicle over a 72 km highway circuit in light traffic. Flurazepam 30 mg significantly impaired the ability to control the lateral position of the vehicle compared to placebo baseline measurements. The degree of impairment was substantial in the female subjects and was greater in the morning than in the afternoon. Lormetazepam 1 mg showed no residual effect on driving performance. Lormetazepam 2 mg impaired driving performance to some extent on the following morning, 10 to 11 h post administration, but no residual effect was found in the afternoon. All drugs improved sleep quality and prolonged sleep duration to more or less the same extent.

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.

Pharmacokinetics of temazepam compared with other benzodiazepine hypnotics--some clinical consequences

When the various benzodiazepine hypnotics are studied, large differences are seen with regard to their pharmacokinetic properties and metabolism in man. Some are eliminated from the body at a relatively slow rate (e.g. nitrazepam), others are metabolized rather rapidly (temazepam, triazolam). Some benzodiazepine hypnotics have major active metabolites that are slowly eliminated (flurazepam, quazepam), while others have non-active metabolites (temazepam, lormetazepam). In hypnotic treatment, the duration of drug action should be restricted to the duration of the night, hence a compound with a relatively short elimination half-life may represent a more rational choice. An overview is given of the pharmacokinetics of the currently available benzodiazepine hypnotics with emphasis on temazepam and other hydroxylated benzodiazepines.

Antianxiety properties of lormetazepam. A double-blind crossover trial versus diazepam

A double-blind crossover trial was carried out to compare the anxiolytic activity of lormetazepam vs diazepam. After 1 week of placebo, the drugs were administered for 4 weeks (10 drops twice daily) to 10 subjects with anxiety disorders. Each patient received either lormetazepam or diazepam and modifications of symptoms were evaluated through a series of tests at various intervals (days 0, 8, 16, 24, 32 and 40 of the study). Both drugs proved to be effective and significantly superior to placebo. They were both well tolerated.

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.