Adjunct Mirtazapine for Negative Symptoms of Schizophrenia

University of Georgia College of Pharmacy, Albany, Georgia 31701, USA.
Pharmacotherapy (Impact Factor: 2.66). 10/2011; 31(10):1017-30. DOI: 10.1592/phco.31.10.1017
Source: PubMed


Negative symptoms of schizophrenia are characterized by affective flattening, alogia, avolition, and anhedonia and are often nonresponsive to antipsychotic therapy. Because negative symptoms are predictive of poor occupational and social functioning, as well as poor global outcomes, numerous studies evaluating adjunct therapy to antipsychotics have been conducted. This review focuses on the use of the antidepressant mirtazapine as adjunct therapy to antipsychotics for the treatment of negative symptoms of schizophrenia. A literature search of the MEDLINE database (from inception-March 2011) identified eight relevant articles: six were randomized, double-blind, placebo-controlled trials, and two were open-label trials. Of the six randomized trials reviewed, four studies assessed add-on mirtazapine to second-generation antipsychotics, whereas two studies examined add-on mirtazapine to first-generation antipsychotics. Five of the six randomized trials supported the use of mirtazapine for negative symptoms of schizophrenia. Of the two open-label trials, one naturalistic study demonstrated that mirtazapine add-on therapy to clozapine was not associated with improvements in negative symptoms; however, this study focused primarily on improvements in cognition, not negative symptoms. An open-label extension phase to a randomized controlled trial showed that mirtazapine continued to produce significant improvement in negative symptoms over a longer duration of time, when added to first-generation antipsychotic therapy. Overall, mirtazapine appears to be well tolerated and associated with few drug interactions. Although adjunct mirtazapine to antipsychotics has been shown to be effective at doses of 30 mg/day in most of the trials, limitations of these studies include short study duration and small sample sizes. To improve generalizability, larger multicenter studies with broader inclusion criteria should be conducted. In addition, studies of longer duration that use different mirtazapine dosages are needed to further assess the benefits of mirtazapine for negative symptoms of schizophrenia.

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    • "In contrast, antidepressants seem to be effective in treating negative symptoms in schizophrenia [125] [126]. "
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    ABSTRACT: Context: Despite advances made in treating the positive symptoms of schizophrenia, treatment of negative symptoms remains an unmet therapeutic need. Adjunctive mirtazapine has shown promise for treatment of negative symptoms in several small clinical trials.Objective: To assess the efficacy of mirtazapine as an adjunctive treatment of negative symptoms in patients with chronic schizophrenia via meta-analysis.Data Sources: A systematic literature review of articles in English and Spanish was conducted in November 2011 by searching PubMed, the Cochrane Library, the Clinical Trial Registry of the NIH, and SIGLE (System for Grey Literature in Europe). Free text search terms for PubMed were 'schizophrenia,' 'negative symptoms' and 'mirtazapine.' Publication date was not a limitation.Study Selection: Studies of people with schizophrenia/schizoaffective disorder were included in the meta-analysis if they were randomized, double-blind, and used the Positive and Negative Symptom Scale (PANSS) as an outcome measure. Nine studies were initially identified. Five studies were included in the meta-analysis; 1 study was excluded for not using the PANSS, 3 were excluded as representing duplicate publications and open label phases of one of the selected randomized control trials. Studies varied in the quality of their selection for participants with primary negative symptoms.Results: Three of the 5 studies showed significant improvement in negative symptoms individually. The overall analysis showed improvement in negative symptoms with an effect size of 1.00 (0.084-1.918), which was statistically significant (p=0.032). Data from the negative symptoms subscale of the PANSS from 169 subjects was used in a forest plot to illustrate the relative strength of treatment effects. The variation in standard median deviation (SMD) attributable to heterogeneity was 27.35 %, indicating a high degree of heterogeneity.Conclusions: This meta-analysis supports the hypothesis that adding mirtazapine to treatment with antipsychotics can improve negative symptoms in schizophrenia. However, additional studies with more stringent negative symptom selection criteria and homogeneous use of antipsychotics are needed.
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