Plasma concentrations of diazepam and desmethyldiazepam during chronic diazepam therapy.

1 Plasma concentrations of diazepam and its metabolite, desmethyldiazepam, have been measured in both in- and out-patient groups treated with diazepam for periods varying between 1 month and 10 years. 2 The diazepam concentration was directly related to the dose of diazepam ingested and inversely related to the age of the patient. 3 A highly significant relationship was obtained between the concentration of desmethyldiazepam and diazepam. 4 The plasma concentrations of both diazepam and its metabolite were independent of sex, duration fo therapy and patient group.