5-HT2 receptor antagonism in dysthymic disorder: a double-blind placebo-controlled study with ritanserin.

Thirty patients suffering from dysthymic disorder participated in a 6-week double-blind trial comparing ritanserin 10 mg and placebo. After a single-blind placebo wash-out period of one week, the test medication was administered during 5 weeks on a double-blind basis. Twenty-three patients completed the study. At the end of the trial, ritanserin was significantly superior to placebo in its effect as manifested on the 19-item Hamilton Rating Scale for Depression, the Hamilton Rating Scale for Anxiety and the State Trait Anxiety Inventory X-1 and X-2. At the end of the study, the therapeutic effect was rated marked or moderate in 75% of the ritanserin-treated patients, but only in 18% of the controls. These data are consistent with the hypothesis of serotonin abnormalities in dysthymic disorder and suggest a therapeutic role of 5-HT2 antagonists. Ritanserin treatment was very well tolerated; no serious adverse experiences were reported.