Catechol-O-methyltransferase activity: A determinant of levodopa response

Abstract

In 14 patients with Parkinson''s disease on long-term therapy the erythrocyte catechol-O-methyltransferase activity correlated with the average plasma concentration ratio of 3-O-methyldopa to L-dopa and with the fasting plasma concentration ratio of 3-O-methyldopa to L-dopa. Patients with the higher erythrocyte catechol-O-methyltransferase activities were those with less favorable clinical responses to L-dopa. As erythrocyte catechol-O-methyltransferase activity may reflect the activity of that enzyme in the major metabolizing tissues, catechol-O-methyltransferase activity would seem to be a significant determinant of response to L-dopa.