STUDY3
A third study compared the efficacy and side effects of alprazolam, diazepam, and placebo in patients with anxiety (4). Of the 235 patients who participated 
in the 28-day study, 78 were given alprazolam, 85 were given diazepam, and 72 were given placebo. Two-thirds of the patients were diagnosed as having anxiety, one-third as having anxiety with depressive mood, and one patient as having obsessive-compulsive neuroses, according to the DSM-III classifications. Although patients had to be at least moderately anxious to be included in the study, the majority were diagnosed as being markedly, severely, or extremely anxious. At the end of the study, 80.3% of the alprazolam-treated patients and 60% of the diazepam-treated patients showed a moderate or marked improvement according to the Physician’s Global Impressions, whereas 62.2% of the patients who had received placebo showed no improvement or their condition worsened. The results of the other four evaluation scales, including the HARS, substantiated the effectiveness of alprazolam at an average daily dose of 1.5 mg and diazepam at an average daily dose of 18.6 mg. Side effects experienced by patients taking alprazolam were fewer and less
severe than those with diazepam or even with placebo. Drowsiness, one of the most common complaints of the patients taking diazepam, occurred less than one-half as often in patients taking alprazolam as in patients taking diazepam. In addition, no patients in the alprazolam group dropped out because of side effects, whereas four patients in the diazepam and two patients in the placebo groups left for this reason. The results of the study established that alprazolam was at least as effective as diazepam in alleviating anxiety, with the advantage of fewer side effects — most notably the decreased incidence of drowsiness.