Anticholinergic challenge and neuroleptic withdrawal. Changes in dyskinesia and symptom measures.

Benztropine mesylate (intravenous [IV] and oral) challenge was compared with brief neuroleptic withdrawal on dyskinesia ratings and symptom measures. Thirty-six neuroleptic-treated patients underwent a placebo-controlled acute IV challenge with 2 mg benztropine and a placebo-controlled two-week trial of oral benztropine mesylate (2 mg three times a day), followed by a double-blind placebo-controlled neuroleptic withdrawal involving four weeks of dose tapering and six weeks of placebo treatment. Benztropine given IV had no significant effect.