Peripheral benzodiazepine binding sites on platelet membranes are increased during diazepam treatment of anxious patients.

Reduced (24%) [3H]PK 11195 binding capacity to platelet membranes was observed in anxious patients in comparison to age- and sex-matched normal controls. Four weeks of diazepam treatment induced elevation (69%) in the maximal number of binding sites, and 1 week of drug withdrawal resulted in a slight decrease (16%) in 'peripheral' benzodiazepine binding sites as compared to their level during treatment.