Hypnotic and residual effects of temazepam in volunteers

The effects of repeated doses of temazepam and nitrazepam on several measures of human performance

The effects of six nightly doses of temazepam (20 mg), nitrazepam (10 mg) and placebo on saccadic eye movements, critical flicker fusion threshold, choice reaction time and mood were studied in eight volunteers. Performance was measured on nights 1 and 6 of each treatment. Nitrazepam produced a residual performance impairment on night 1 that disappeared by night 6, despite higher serum concentrations of the drug on the sixth night of treatment. Temazepam, with a shorter elimination half-life, produced no significant performance impairment on night 1, but by night 6 a significant impairment of saccadic eye movements (p less than 0.05) was seen 1 hour after drug intake. We conclude that tolerance to the sedative action of nitrazepam developed over the 6-night period of the study. No evidence of tolerance was seen with temazepam. No residual effects of temazepam (20 mg) were seen the morning after the night-time drug administration.

The effect of repeated doses of temazepam and nitrazepam on human psychomotor performance

The effects of six nightly doses of temazepam (20 mg), nitrazepam (10 mg) and placebo on saccadic eye movements, critical flicker fusion, choice reaction time and on subjective feelings were studied in a double blind cross-over study in eight volunteers. Testing was performed on nights 1 and 6 of treatment. Nitrazepam, a benzodiazepine with a long elimination half-life produced a residual performance impairment on night 1 that had disappeared by night 6, despite higher serum concentrations of the drug on the sixth night of treatment. Temazepam, with a shorter elimination half-life produced no significant performance impairment on night 1, but by night 6 a significant impairment of saccadic eye movements (P less than 0.05), was seen 1 h after drug intake. We conclude that tolerance developed to the sedative action of nitrazepam over the 6 night period of the study. No evidence of tolerance was seen with temazepam.

An investigation into the interaction between ethanol at low doses and the benzodiazepines nitrazepam and temazepam on psychomotor performance in normal subjects

Ten healthy male volunteers received, in randomized order, temazepam 20 mg, nitrazepam 5 mg or placebo in combination with ethanol 0.1, 0.2 or 0.4 g/kg. Psychomotor tests were performed at regular intervals over 8 h. Ethanol alone at 0.4 g/kg significantly showed simple reaction time for between 30 and 60 min, whereas nitrazepam (5 mg) or temazepam (20 mg) plus the placebo alcohol dose (0.1 g/g) had no significant effect. The benzodiazepines and ethanol (0.2 and 0.4 g/kg) in combination showed no potentiation or prolongation of action. Both ethanol and the two benzodiazepines significantly reduced critical flicker detection in themselves and, in combination, had additive effects. Only nitrazepam and temazepam produced decreases in performance in the code substitution (DSST) test, and the time course of action of nitrazepam was markedly longer than that of temazepam. Ethanol alone had no detectable effect on immediate recall, prompted recall, learning, or word recognition tests. Both benzodiazepines reduced immediate and prompted recall and nitrazepam, in addition, reduced word recognition ability. It is concluded that the spectrum of CNS depressant actions of ethanol and the benzodiazepines are different and that there is no evidence of a potentiation or prolongation of their effects by concomitant administration of the doses used in the present study.

Temazepam (Restoril, Sandoz Pharmaceuticals)

Temazepam is a benzodiazepine derivative indicated for the treatment of insomnia. Pharmacokinetic studies of the hard capsule formulation indicate that the mean time to peak is 2.99 hours and the mean elimination half-life is 14.7 hours. Sleep laboratory studies have demonstrated improvements in all sleep parameters except sleep onset latency. Clinically, patients report improvements in all sleep parameters including sleep onset latency. The efficacy of temazepam compares favorably with barbiturates, glutethimide, nitrazepam, lorazepam, oxazepam, and flurazepam. It has not been compared with diazepam in the clinical setting. Side effects include drowsiness, dizziness, and lethargy. The incidence of hangover effects from 15- and 30-mg doses is relatively low. Temazepam has no proven advantages over other benzodiazepine hypnotics. The major issues that need further clarification include temazepam's sleep induction properties and the relative incidence of hangover and rebound insomnia when compared with longer-acting benzodiazepines.

Evaluation of temazepam as a hypnotic

Temazepam is a 1,4-benzodiazepine, newly marketed in the United States for the symptomatic treatment of the complaint of insomnia. The manufacturer recommends a dose of 30 mg before bedtime for most adults and 15 mg for geriatric or debilitated patients. A dose of 30 mg usually produces peak plasma concentrations within 3 hours after oral ingestion and has a mean half-life of 10 to 15 hours. Thus, temazepam is absorbed more slowly and metabolized more quickly than flurazepam, the only other benzodiazepine marketed in the United States specifically for insomnia. Eight sleep laboratory and 21 clinical studies on temazepam indicate that temazepam reduces awakening during the night and increases sleep duration. However, there was no consistent evidence that temazepam reduces sleep latency--probably because temazepam, taken at bedtime, does not reach sufficiently high blood levels in time to affect sleep onset. One sleep laboratory study on 8 insomniac patients given 35 consecutive nightly doses of 30 mg found no evidence of tolerance or rebound insomnia. Studies on tolerance, metabolism and carry-over effects have shown that temazepam has no long-acting metabolites and does not affect waking function following use at bedtime. In patients for whom hypnotic medication is appropriate, temazepam should be an effective drug for reducing most symptoms of insomnia.

Temazepam: a review of its pharmacological properties and therapeutic efficacy as an hypnotic

Temazepam is a benzodiazepine drug which is a minor metabolite of diazepam. In clinical studies using subjective evaluation methods it was effective for maintaining sleep and increasing total sleep time. However, sleep laboratory studies did not show a significant effect on some sleep parameters, especially sleep induction. Temazepam has a relatively short half-life (about 5 to 11 hours, longer in some subjects and in the elderly), and no active metabolites of clinical importance, and thus may be considered more suitable for use as an hypnotic than longer acting drugs such as diazepam, nitrazepam or flurazepam when residual sedative effects the next day are not desirable. Indeed, few residual effects on morning performance appear to occur with usual single doses of temazepam, although at the upper end of the recommended dosage range (30 mg or more) some evidence of impaired psychomoter and cognitive function in the morning has been reported. Whether or not temazepam is likely to produce "hangover" with repeated night-time administration needs further clarification. While a call for a large number of controlled trials may not be justifiable in evaluating a new hypnotic, a few well designed additional comparative studies in insomniac subjects are needed to assess adequately the relative merits of temazepam (particularly with regard to sleep onset) compared with other benzodiazepine hypnotics, especially those which are short- or intermediate-acting.