L-dopa therapy in Parkinson's disease: a critical review of nine years' experience.

The last 10 years have seen great activity in the investigation of cerebral catecholamines, particular attention having been paid to dopamine. The low dopamine content in the basal ganglia and in the urine of patients with Parkinson's disease led to the logical use of the precursor DOPA in the treatment of this disorder. Between 1961 and 1966, both the oral and the intravenous routes were utilized and some effects were noted upon akinesia and rigidity. The doses then used were low and the results remained somewhat controversial. When higher oral levels of L-dopa were introduced, the beneficial action of L-dopa upon parkinsonian symptoms and signs was proved beyond doubt, but there came to light a number of troublesome side effects, the worst of which were hypotension and a variety of abnormal involuntary movements. Recently, new approaches to the therapy have been tried and the sum total of these observations is to challenge our peace of mind regarding a seemingly logical chain of events. We are convinced that such second thoughts will eventually result in better and safer methods of treating this too frequent and disabling neurological disorder.