Objective: To evaluate the efficacy and safety of mirtazapine in depressed outpatients who have shown nonresponse or intolerance to selective serotonin reuptake inhibitor (SSRI) therapy.
Method: In this open-label, 8-week study, the efficacy and safety of mirtazapine among 103 outpatients with DSM-IV major depressive disorder who had failed previous therapy with an SSRI (fluoxetine, paroxetine, or sertraline) were evaluated. The primary efficacy measure was the 17-item Hamilton Rating Scale for Depression (HAM-D-17), and safety assessments included reported adverse events, routine laboratory assessments, physical examinations, and assessments of vital signs. A 4-day washout period followed by mirtazapine treatment was compared with an immediate switch from the SSRI to mirtazapine.
Results: Based on mean HAM-D-17 scores at endpoint and response rates of 48% based on the criterion of > or = 50% reduction in HAM-D-17 score, mirtazapine was found to be an effective treatment for a substantial proportion of patients for whom an SSRI was ineffective and/or poorly tolerated. Mirtazapine was well tolerated, with sedation and appetite increase/weight gain the most commonly reported adverse events. In addition, no difference in efficacy, safety, or tolerability was observed for patients undergoing an immediate switch from an SSRI (after having been tapered to the minimal effective dose) to mirtazapine, compared with those undergoing the imposition of a 4-day drug-free washout.
Conclusion: These results suggest that an immediate switch to mirtazapine may be a valid therapeutic option among patients who cannot tolerate or do not respond to SSRIs.