Pharmacokinetic and clinical considerations in the choice of a hypnotic.

1 Not only has insomnia become much more frequent in the last hundred years but its causes have also changed considerably. 2 In the treatment of insomnia, benzodiazepines—because of their additional anxiolytic effect—offer substantial advantages over other sleep-inducing agents. 3 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. 4 Midazolam has the lowest residual fraction of all known benzodiazepines and thus, administered in the appropriate dosage, also has the shortest duration of activity.