A 24-week study of 20 mg citalopram, 40 mg citalopram, and placebo in the prevention of relapse of major depression.

A total of 147 patients who had responded in a placebo-controlled study to 6 weeks treatment of an episode of DSM-III-R major depression with either 20 mg or 40 mg citalopram were randomized double-blind to continue on the same dose of citalopram or to receive placebo during a 24-week study of the efficacy of citalopram in the prevention of relapse. The citalopram 20 and 40 mg groups showed a significant advantage compared with placebo both in relapses (p < 0.05) and in the survival analysis of time to relapse (p = 0.01 and p = 0.02, respectively). Both 20 and 40 mg citalopram appeared similarly safe and well tolerated with little difference in side effects from placebo. The results demonstrate that citalopram, at a dose of both 20 and 40 mg is effective and well tolerated in continuation treatment to consolidate response. The relapse rate in patients who had responded to placebo during the 6-week acute treatment study, who were continued double-blind with placebo but not included in the efficacy analysis, was similar to the rate in the formal placebo control group, suggesting that patients who respond to placebo in a short treatment course may nonetheless require long-term active treatment to prevent relapse.