The effect of nonsedating doses of diazepam on regional cerebral blood flow.

Drugs like diazepam induce tranquilization in small doses and sedation in larger quantities. Regional cerebral blood flow (rCBF) was measured before and 5 min after the intravenous administration of nonsedating doses of diazepam or placebo (given on a double-blind basis) to 20 right-handed volunteers. Subjects who received diazepam showed marked right hemispheric rCBF decreases, especially in the frontal lobe, whereas controls did not show significant differences between the two sets of values. None of the subjects became sleepy during the experiment.