Stated briefly, our objectives are as follows: a) to investigate changes in drug metabolism associated with the aging process by delineating the relative importance and interrelationships of selected pathways (e.g., dealkylation, hydroxylation, glucuronidation) in older persons taking specific (model) benzodiazepines selected to illuminate each pathway. Younger adults will be studied for comparative purposes; b) to determine blood levels for bqnzodiazepines in patients receiving emergency room care for benzodiazepine overdosage; to assess the relationship between blood levels and morbidity; and to evaluate the usefulness of these levels for clinical care and treatment planning; c) to continue our studies of drug interactions; d) to investigate the development of tolerance (physiological) to benzodiazepines by studying changing threshholds to amobarbital-induced bilateral gaze nystagmus in subjects taking benzodiazepines for varying amounts of time; e) to continue to improve the practicing clinician's understanding of rational therapeutic approaches by extending our educational efforts in clinical psychopharmacology.