Prescribing short-acting hypnosedatives. Current recommendations from a safety perspective.

The duration of action of hypnosedative drugs is mainly determined by their pharmacokinetic properties. The ideal drug should induce sleep within 30 min and maintain a normal pattern of sleep for 6 to 8h, with little or no residual effects the next morning. Clinically, 4 types of insomnia can be distinguished: prolonged latency, 1 to 2 long periods of wakefulness, frequent short awakenings and early morning awakening. An ultra-short-acting drug (2 to 3h), such as triazolam, is useful for prolonged latency. Temazepam, lormetazepam and loprazolam provide more prolonged effects (8 to 10h). These benzodiazepines are not free of daytime adverse effects, particularly drowsiness, dependency potential, rebound insomnia and habituation to the drug effect. Zopiclone and zolpidem are new nonbenzodiazepine hypnotics that are as effective as benzodiazepines but without the problems associated with the latter. They produce a more normal electroencephalogram sleep pattern and so would seem to approach to the ideal hypnosedative for the future. However only further clinical trials and widespread use in practice will determine whether they will live up to this potential.