Efficacy trial of the 5-HT2 antagonist MDL 11,939 in patients with generalized anxiety disorder.

The purpose of this study was to assess the anxiolytic effect of MDL 11,939, a selective 5-HT2 receptor antagonist, in patients with generalized anxiety disorder. After a 1-week placebo lead-in period, 72 healthy male outpatients meeting DSM-III-R criteria for generalized anxiety disorder were randomized to MDL 11,939, 32 mg thrice daily (N = 37), or placebo (N = 35) for 6 weeks. At the end of treatment, MDL 11,939 showed a 7.2-point (30%) decrease in Hamilton Rating Scale for Anxiety scores compared with a 5.7-point (23%) decrease with placebo, but the difference was not significant (p > 0.05). The incidence of adverse events between treatments was similar. MDL 11,939 was well tolerated but did not demonstrate significant anxiolytic effects in this pilot study.