A multi-centre comparison of prazepam and diazepam in the treatment of anxiety.

A single-blind, parallel group, multi-centre study was carried out in 2009 patients with an anxiety state to compare the efficacy, tolerance and withdrawal effects of prazepam and diazepam in therapeutically equivalent doses. Patients were allocated at random to receive 30 mg prazepam or 15 mg diazepam per day, either in divided dosage (3 times) during the day or as a single large dose at night. After a 2-week treatment period, drug therapy was withdrawn gradually. Patients were followed-up at weekly intervals over the 4-week study period. Hamilton Anxiety Rating Scale scores and physicians' global assessment of response at each visit indicated that whilst both drugs and dosage regimens were effective patients treated with diazepam responded rather less well and had a greater return of anxiety symptoms after therapy was stopped compared to those on prazepam. Moreover, the prazepam-treated patients, especially those on the divided daytime dosage regimen, had fewer and milder side-effects in the early treatment period. Dizziness was least apparent in the prazepam single night time dosage group and it is suggested that this may be an important practical consideration in the treatment of anxiety in the elderly.