Efficacy of low-dose mirtazapine in neuroleptic-induced akathisia: A double-blind randomized placebo-controlled pilot study

The nonselective serotonin (5-HT)-2A antagonists ritanserin, mianserin, and cyproheptadine were found efficacious in neuroleptic-induced akathisia (NIA). Mirtazapine is structurally and pharmacologically similar to mianserin, and the authors sought to determine its anti-NIA activity. Twenty-six neuroleptic-treated schizophrenic patients with DSM-IV diagnosis of NIA received add-on mirtazapine (15 mg/day) or placebo for 5 days in a double-blind design. Patients were assessed at baseline and days 3 and 5 with the Barnes Akathisia Scale (BAS), Positive and Negative Symptom Scale, Hamilton Rating Scale for Depression, and Simpson-Angus Scale for parkinsonism. Analysis of covariance with repeated measurements revealed significant group X time effects in favor of the mirtazapine group in both completers (n = 10 in each group) and intent-to-treat analysis (n = 13 in each group) for the BAS global subscale (F[1, 17] = 14.87, p = 0.001, and F [1, 23] = 13.24, p = 0.01, respectively) and objective subscale (F [1, 17] = 8.25, p = 0.011, and F [1, 23] = 7.35, p = 0.012, respectively) and borderline significant superiority for the BAS subjective subscale (F [1, 17] = 4.39, p = 0.051, and F [1, 23] = 4.12, p = 0.054, respectively) and distress subscale (F [1, 17] = 4.21, p = 0.056, and F [1, 23] = 3.80, p = 0.064, respectively). Significantly more mirtazapine- than placebo-treated patients (53.8% [7/13] vs. 7.7% [1/13], respectively; χ² = 8.3, p = 0.004) met operational respons criterion, a reduction of at least two points on the BAS global subscale. Mirtazapine treatment was associated with modest improvement of psychotic and parkinsonian symptoms. Mild sedation was the only side effect. Our study demonstrated that mirtazapine (15 mg/day) is an efficacious and well-tolerated therapeutic option in NIA. Marked 5HT2A/2C antagonistic activity of mirtazapine apparently accounts for its anti-NIA activity. The role of mirtazapine in the treatment of akathisia induced by atypical antipsychotic agents merits further investigation.