Benzodiazepine hypnotics: sorting the pharmacokinetic facts.

Five benzodiazepine derivatives are currently approved for the treatment of sleep disorders. Important differences exist among the drugs in the physicochemical properties of lipid solubility and protein binding and in pharmacokinetic properties of absorption, distribution, elimination, and clearance. These differences may account for observed variations in clinical action and side effects during and after treatment. Bases for understanding and predicting differences among benzodiazepine hypnotics are discussed.