Changes in extrapyramidal symptoms following anticholinergic drug withdrawal.

An antiparkinson drug (APK) withdrawal study was carried out in 34 schizophrenic outpatients on maintenance neuroleptics. Sixty-five percent of patients were without major complaints after 2 weeks of APK discontinuation, while 35% reported adverse effects including extrapyramidal, autonomic, and behavioral symptoms. Male patients and those on higher diethazine doses before withdrawal reported more complaints. Ratings showed significant increases of parkinsonism, as well as dyskinesia following APK withdrawal. No clinical evidence was obtained in support of the notion of cholinergic hypersensitivity in patients showing "tremors" at baseline.