[Pharmacokinetic of benzodiazepines in old age]

The elimination half-life of chlordiazepoxide and diazepam increases with age, and this may cause prolongation of action after a single dose and delayed accumulation on multiple dosing in elderly patients. Since the total body clearance of chlordiazepoxide is also reduced, higher steady-state serum concentration is to be expected in patients over 60 years of age. Desmethyldiazepam, one of the active metabolites of diazepam and chlordiazepoxide with a long elimination half-life, also shows impaired elimination in old persons. Prolongation of half-life without changes in total body clearance has been demonstrated for nitrazepam and temazepam. In contrast, oxazepam and lorazepam do not show clinically significant changes of pharmacokinetics with age. The clinical implications of the different pharmacokinetic characteristics are discussed.