Diazepam dose preference in humans

Diazepam dose preference was studied in 10 human subjects in a hospital setting. Subjects were allowed to select between a standard compound (diazepam or pentobarbital) and one of several doses of diazepam (2–40 mg/capsule) on an ad lib basis. When 5 or 10 mg/capsule diazepam was the standard, no clear cut diazepam dose preference was found. When 30 or 50 mg/capsule pentobarbital was the standard, clear cut diazepam dose preference in some subjects was found. The shape of the dose preference function differed among subjects. Within subjects, diazepam dose preference differed within the self-administration day, with some subjects preferring one dose in the morning and a different dose later in the day.