Antagonism of Levodopa by Papaverine

Abstract

PAPAVERINE, the isoquinoline alkaloid, is widely employed in various formulations in the treatment of patients believed to be suffering from cerebral arteriosclerosis. Patients with Parkinson disease may thus be given papaverine preparations when symptoms are suggestive of cerebral vascular insufficiency or appear to represent instances of arteriosclerotic parkinsonism. It seems important, therefore, to call attention to an antagonistic effect of papaverine on the therapeutic response to levodopa recently observed in several patients. The clinical features of this unexpected interaction are illustrated by the first patient in which they were recognized. Report of a Case A 71-year-old woman with Parkinson disease of 20 years' duration had responded extremely well to levodopa therapy when it was started in 1968. Subsequently she enjoyed further, sustained improvement despite moderate choreiform dyskinesia on a combined regimen of levodopa and carbidopa from 1971 through May 1974. Then she began to complain of difficulty concentrating, a sense