Pharmacology of benzodiazepine hypnotics.

The "revolution" in pharmacologic treatment of insomnia began in 1970 with the availability of flurazepam, the first of the benzodiazepine hypnotics. Flurazepam largely replaced all other hypnotics during the decade of the 1970s. The second revolution began in the early 1980s as shorter half-life hypnotics, triazolam and temazepam, became available and began to replace flurazepam. The decade of the 1990s will probably see a more balanced pattern of benzodiazepine hypnotic use, as well as use of newer nonbenzodiazepine hypnotics. Among available benzodiazepines, all have the capacity to produce dose- and concentration-dependent sedation, drowsiness, performance impairment, and amnesia. Benzodiazepine-induced amnestic effects are characterized by either impairment of information acquisition, impairment of consolidation and storage, or both. In general, apparent clinical differences among benzodiazepine hypnotics are explained by differences in pharmacokinetic properties of absorption, distribution, elimination, and clearance.