Multicenter, placebo-controlled, fixed-dose study of citalopram in moderate-to-severe depression

Citalopram, the most selective serotonin reuptake inhibitor (SSRI), is a bicyclic phthalane derivative with a chemical structure that is unrelated to that of other SSRIs and available antidepressants. The drug is approved for use in 69 countries. This 6-week, fixed-dose, placebo-controlled, parallel-arm, multicenter trial was performed to confirm its efficacy and safety in treatment of outpatients with major depression in the United States.

Six hundred and fifty adult outpatients with moderate-to-severe major depression (DSM-III-R) were randomly assigned to receive citalopram at doses of 10 mg (N = 131), 20 mg (N = 130), 40 mg (N = 131), or 60 mg (N = 129) or placebo (N = 129) once daily. Outcome assessments were the 21-item Hamilton Rating Scale for Depression (HAM-D), the Montgomery-Asberg Depression Rating Scale (MADRS), and the Clinical Global Impressions scale.

Between-group comparisons of the change from baseline to endpoint revealed significantly greater improvement in the citalopram patients relative to the placebo patients on all 3 efficacy measures. Patients randomly assigned to 40 mg/day and 60 mg/day of citalopram showed significantly greater improvement than placebo on all efficacy measures, as well as on the HAM-D symptom clusters measuring depressed mood, melancholia, cognitive disturbance, and psychomotor retardation. Patients who received 10 mg/day and 20 mg/day of citalopram also showed consistent improvement relative to placebo on all efficacy ratings, with statistical significance demonstrated in the MADRS response rate, the HAM-D depressed mood item, and the HAM-D melancholia subscale. Citalopram was well tolerated, with only 15% of patients discontinuing for adverse events. The side effects most commonly associated with citalopram treatment were nausea, dry mouth, somnolence, insomnia, and increased sweating.

Citalopram was significantly more effective than placebo in the treatment of moderate-to-severe major depression, especially symptoms of depressed mood and melancholia, with particularly robust effects shown at doses of 40 and 60 mg/day. Citalopram was well tolerated in spite of forced upward titration to fixed-dose levels, with a low incidence of anxiety, agitation, and nervousness.