Mirtazapine for Neuroleptic-Induced Akathisia

Mr. A was a 28-year-old unmarried man who came in for treatment after a 3-month history of persecutory delusions, auditory hallucinations, and bizarre behavior. He had no previous or family history of psychiatric illness or drug abuse. The results of a neurological evaluation, EEG, routine blood and urine tests, serum electrolyte measurements, and urea, liver, and thyroid function tests were within normal limits. A DSM-IV diagnosis of schizophreniform disorder was established, and treatment with haloperidol, 10 mg/day, was initiated. Four days later, Mr. A complained of leg restlessness, an inability to sit still, and a constant urge to move. His global score on the Barnes Akathisia Scale was 4 (“marked akathisia”). Administration of biperiden (4 mg b.i.d. for 5 days) with the subsequent addition of diazepam (10 mg/day for 3 days) had no effect on the severity of his neuroleptic-induced akathisia.

Mr. A consented to the addition of mirtazapine (15 mg at 8:00 a.m. for 5 days). Substantial relief of the subjective component of the akathisia, accompanied by a disappearance of the akathitic movements, was noted on the second day of mirtazapine treatment. Mr. A’s score on the Barnes Akathisia Scale dropped to 1. Discontinuation of mirtazapine on the fifth day led to a partial recurrence of the akathisia (Barnes Akathisia Scale score: 3), but a rechallenge (for 7 days) completely ameliorated his symptoms (Barnes Akathisia Scale score: 0). Mild transient sedation was the only side effect.