Comparison of amantadine, placebo, and levodopa in Parkinson's disease

A double-blind crossover trial of amantadine hydrochloride and placebo, each given for three-week periods, was performed on 40 outpatients with Parkinson9s disease. Conventional antiparkinsonian drugs were continued during the six-week period. Amantadine was effective by objective measurements (timed tests) and subjective ratings of tremor and rigidity. Amantadine produced an average 16 percent objective improvement over base line in the 40 patients. At the end of a third three-week period, during which conventional drugs had been stopped, amantadine produced a 21 percent improvement compared with base line. After six to nine weeks of levodopa added to amantadine, there was a 28 percent improvement over base line. Amantadine appears to be a useful adjunct in the treatment of Parkinson9s disease, and amantadine and levodopa together may be effective combination therapy.