Mirtazapine monotherapy versus combination therapy with mirtazapine and aripiprazole in depressed patients without psychotic features: A 4-week open-label parallel-group study

Background: There is preliminary evidence that the atypical antipsychotic aripiprazole, which is a partial agonist at D-2 and 5-HT1A receptors and a potent antagonist at 5-HT2A receptors, may be useful as an augmentation strategy in treatment-resistant depression. Method: In this 4-week open-label non-randomized parallel-group study, the safety and efficacy of aripiprazole as add-on treatment strategy in patients suffering from non-delusional depression was investigated. Forty drug-free depressed inpatients without psychotic symptoms (13 men, 27 women), suffering from a major depressive episode or bipolar disorder, depressive state (DSM-IV criteria), were included in the study. The patients were treated either with mirtazapine monotherapy (45 mg/day) or combination therapy (mirtazapine 45 mg/day plus aripiprazole 15 mg/day) for 4 weeks. Safety and efficacy were assessed weekly using the Hamilton Depression Rating Scale, the Simpson-Angus Scale and the Barnes Akathisia Scale. Results: Mirtazapine monotherapy and combined treatment with mirtazapine and aripiprazole showed comparable antidepressant effects as assessed at the endpoint of the study period. However, additional administration of aripiprazole accelerated the onset of antidepressant action in patients suffering from treatment-resistant depression. Additive use of aripiprazole reduced the mirtazapine-induced increase in the body mass index. Moreover, mirtazapine had favourable effects on aripiprazole-induced akathisia. No other extrapyramidal side effects were seen in the combination therapy group. Conclusion: Combined therapy with mirtazapine and aripiprazole is a safe and well-tolerated treatment option which may be useful especially in treatment-resistant depression. Double-blind controlled studies are needed to further explore the efficacy and safety of aripiprazole in depressed patients.