Pharmacokinetic and clinical considerations in the choice of a hypnotic.

Not only has insomnia become much more frequent in the last hundred years but its causes have also changed considerably. In the treatment of insomnia, benzodiazepines--because of their additional anxiolytic effect--offer substantial advantages over other sleep-inducing agents. The residual fraction--the quotient of plasma concentration at 12 h after drug intake to maximum plasma concentration--makes it possible to differentiate between the benzodiazepines according to their suitability as anxiolytics or hypnotics.