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

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.

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.

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.

A large-scale controlled evaluation is warranted to substantiate clinical utility of off-label use of mirtazapine (7.5 mg) for patients with AAA.