Gradual withdrawal of long-term anticholinergic antiparkinson medication in Chinese patients with chronic schizophrenia

Previous antiparkinson drug withdrawal studies involving white subjects hav e yielded inconclusive findings, whereas there is a paucity of data concern ing Asian patients. A double-blind, placebo-controlled, randomized trial us ing gradual withdrawal of antiparkinson medication was conducted to evaluat e the need for maintenance antiparkinson therapy for clinically stable Chin ese patients with chronic schizophrenia. Seventy-five schizophrenic subjects who had received a diagnosis according to DSM-IV who had been ill for at least 5 years and on antipsychotic and an tiparkinson medication for a minimum of 2 years entered the study. After ba seline assessment, 58 subjects were matched according to age, sex, age at o nset, length of illness, dose and length of antipsychotic and antiparkinson medication, and the presence of various extrapyramidal side effects. Rando mly assigned dose-reduction and control groups were formed consisting of 29 subjects each. Trihexyphenidyl (THP), the only oral antiparkinson drug use d in the study, was reduced by 1 mg every 2 weeks, whereas other psychotrop ic medication remained unchanged. Monthly assessment was performed using th e Brief Psychiatric Rating Scale, Hamilton Bating Scale for Depression, Abn ormal involuntary Movement Scale, Simpson-Angus Scale, Barnes Akathisia Rat ing Scale, and the Nursing Observation Scale for Inpatient Evaluation-30, C omplete withdrawal of THP was possible in 25 (90%) of the 28 subjects who c ompleted the study, whereas considerable dose reduction was achieved in the remaining 3 subjects. There were no significant differences be-tween dose reduction and control groups on any of the rating scales at the completion of the study. Our results suggest that long-term prophylactic administratio n of antiparkinson medication is unnecessary in the treatment of the majori ty of Chinese patients with chronic schizophrenia because withdrawal was ac complished without adverse mental or motor effects.