Sleep laboratory study of lormetazepam in older insomniacs

Lormetazepam is a new benzodiazepine hypnotic. Previous work has indicated that lormetazepam has an intermediate to short elimination half-life, i.e. in the range of 5-15 h. Hence, in older patients, the drug should be safe and hypnotically active in doses equal to or less than the doses recommended for young adults. The present study tested this hypothesis. We studied ten healthy subjects, aged 55 and older, with both subjective and objective insomnia. Subjective insomnia was the complaint of requiring at least 45 min to fall asleep and sleeping less than six and a half hours per night. Each complaint was present on at least 50% of the nights for at least three months. Objective insomnia was measured polysomnographically and was present on at least two of the last three nights of four consecutive nights of placebo baseline. The study involved a design in which treatment was administered in a double-blind fashion. Each subject was studied for 14 consecutive nights in the sleep laboratory. The drug was administered for seven consecutive nights which were preceded by a placebo baseline and followed by a placebo period of drug withdrawal. On each laboratory night subjects were monitored by continuous, all-night conventional EEG/EOG/EMG recordings. Each laboratory morning subjects completed a questionnaire on which they rated six characteristics of their sleep on the previous night. At study entry and again at study end, each subject had a physical examination by a Board internist and clinical laboratory tests. Each laboratory morning and evening subjects had a screening physical exam and completed an 11-item hypnotic drug side-effect questionnaire and a 56-item review of medical systems questionnaire. Compared with the median baseline night, on the median drug night lormetazepam 0.5 mg significantly increased total sleep time by about 25 min. The drug's reductions of sleep latency were substantial. In addition, lormetazepam 0.5 mg significantly decreased number of awakenings. No objective evidence was found of either tolerance developing to the hypnotic efficacy of lormetazepam 0.5 mg or of rebound insomnia.