Tardive dyskinesia treated with pimozide.

We have investigated the action of pimozide in tardive dyskinesia induced by prolonged administration of phenothiazines. Improvement was recorded in a double blind study of 18 patients treated with maximum tolerated dosage (mean 18.8 mg/day) for 6 weeks. There was no deterioration in the therapeutic action of pimozide over this time. Parkinsonism and sedation were the main adverse effects. They were corrected by reduction of the dose of pimozide, but often recurred so that further adjustments of dosage were necessary. Our findings support the view that tardive dyskinesia is produced by a disturbance in the balance of central transmitters such that dopaminergic transmission is increased.