Background: Fluvoxamine and paroxetine, both serotonin selective reuptake inhibitors (SSRIs), were compared at two centers in a 7-week double-blind study in outpatients with major depression, diagnosed by DSM-III-R criteria. Method: Sixty patients were randomly assigned to receive dosage titrated upward to between 50-150 mg/day of fluvoxamine (N = 30) or 20-50 mg/day of paroxetine (N = 30). The mean +/- SD daily dose administered at the last assessment was 102 +/- 44 mg/day for fluvoxamine and 36 +/- 13 mg/day for paroxetine. Sixteen (53%) fluvoxamine-treated patients and 10 (33%) paroxetine-treated patients were titrated to the maximum permissible dosage of either drug. Sample size was calculated to provide at least 85% power at 5% level of significance to detect at least a 1.00-point difference in mean severity of adverse events, assuming a standard deviation of 1.0. Results: Fluvoxamine and paroxetine were similarly effective in ameliorating depression as demonstrated by mean total scores of 10.9 +/- 7.3 (p < .00) and 11.5 +/- 7.4 (p < .00), respectively, in the Hamilton Rating Scale for Depression (HAM-D). Adverse events were mostly mild to moderate in severity. The most common events were headache (N = 17, 57%), nausea (N = 14, 47%), sweating (N = 10, 33%), somnolence (N = 9, 30%), diarrhea (N = 9, 30%), dry mouth (N = 8, 27%), dizziness (N = 8, 27%), and, among males, impotence (N = 3, 21%) and ejaculatory abnormality (N = 3, 21%) in the paroxetine group, and headache (N = 12, 40%), somnolence (N = 12, 40%), nausea (N = 11, 37%), dry mouth (N = 11, 37%), insomnia (N = 9, 30%), asthenia (N = 7, 23%), and dyspepsia (N = 7, 23%) in the fluvoxamine group. The only statistically significant difference between treatment groups was for sweating (33% paroxetine vs. 10% fluvoxamine, p = .028). Conclusion: Observed differences in some side effects, although not statistically significant, indicate that when a patient has difficulty tolerating one SSRI, the clinician may choose to change to a different agent within the same class.
