Very Low-Dose Mirtazapine (7.5 mg) in Treatment of Acute Antipsychotic-Associated Akathisia

BACKGROUND: Some evidence suggests that off-label use of mirtazapine (15 mg) is effective in treatment of acute antipsychotic-associated akathisia (AAA). We analyzed whether a lower dose of mirtazapine (7.5 mg) maintained its antiakathisia properties while exhibiting better tolerability in patients with schizophrenia and mood disorders who developed acute AAA. METHODS: Medical charts were retrospectively evaluated for 12 patients with AAA. All scored at least 2 (mild akathisia) on the Barnes Akathisia Rating Scale (BARS) and were treated with mirtazapine (7.5 mg) for a mean of 10.3 days. RESULTS: There was a statistically significant decrease in the BARS subjective, distress, and global (P < 0.01 to P < 0.001), but not objective (P = 0.63), subscales. Five participants (41.6%) fulfilled the predefined criterion of response, a decrease of at least 2 points on the BARS global subscale. The positive antiakathisia effect of mirtazapine was observed predominantly in aripiprazole-treated patients. Mirtazapine (7.5 mg) was well tolerated, and no clinically significant adverse effects, primarily drowsiness or increased appetite, were reported. CONCLUSIONS: A large-scale controlled evaluation is warranted to substantiate clinical utility of off-label use of mirtazapine (7.5 mg) for patients with AAA.