Levodopa in Parkinsonism: Potentiation of Central Effects with a Peripheral Inhibitor

The clinical state achieved with levodopa was compared to that on levodopa plus alpha-methyldopa hydrazine, which blocks conversion of levodopa to dopamine within peripheral tissues only. Five children with dystonia remained unimproved by either regimen. In 26 adults with Parkinsonism less levodopa was needed for symptomatic control when levodopa was given with inhibitor than when used alone. The amount of inhibitor that had to be added to similar doses of levodopa was less in patients who had received levodopa chronically. Rapid induction of therapy, better diurnal symptomatic control and a new capability to administer pyridoxine to patients receiving levodopa constituted advantages of adding inhibitor to levodopa. The main disadvantage of these combinations was the rapid induction of involuntary movements.