Pilot study of a specific serotonergic antagonist, pirenperone, in the treatment of anxiety disorders.

Pirenperone (R 47465) is the prototype of a new class of psychotropic drugs, selective serotonin 5-HT2 receptor blocking agents. In an open pilot study, the anxiolytic properties of pirenperone were evaluated in a sample of five anxious inpatients who met Research Diagnostic Criteria for current Generalized Anxiety Disorder and who had a score of at least 25 on the Hamilton Anxiety Scale (HAS). Three dosage levels were tested: 15, 30 and 60 mg/a day in 3 divided doses. Each dosage period lasted at least 5 days, at the end of which patients were reassessed by HAS, Clinical Global Impression and a side-effects checklist. Results suggested a modest anxiolytic activity, without a clear dose-response relationship and with good tolerance. Subsequent treatment by lorazepam (7.5 mg/d) seemed to result in more specific improvement.