Thiopropazate hydrochloride in persistent dyskinesia.

Thiopropazate (Dartalan) was found to be significantly more effective than a placebo in relieving dyskinesia in 23 patients with functional psychosis and persistent dyskinesia associated with prolonged phenothiazine therapy. Each patient whose dyskinesia had persisted unchanged for at least one month after phenothiazine withdrawal received thiopropazate by mouth for three weeks and the placebo for a similar period. Patients were evaluated before the trial, at three weeks, and at six weeks.The drug also improved psychotic behaviour. Possible side effects, which were generally mild, were noted in eight patients, of whom six had Parkinsonism and four drowsiness. None had side effects while on the placebo.The findings indicate that thiopropazate is of value in persistent dyskinesia associated with prolonged phenothiazine intake-a condition hitherto unresponsive to other treatment. Further research is required to determine the long-term effectiveness of the drug.