A double-blind study of the effects of levodopa in Parkinson's disease.

THERE IS CONSIDERABLE EVIDENCE suggesting that the symptoms of parkinsonism are related to a depletion of striatal dopamine.1-4 Since oral dopamine does not cross the blood-brain barrier, efforts have focused on the systemic administration of L-dopa, dopamine’s imrnediate precursor, which appears to pass through the barrier. Recent studies indicate that L-dopa is rapidly becoming the treatment of choice in parkinsonism.”* In the present study, a double-blind therapeutic trial has been used in the treatment of Parkinson’s syndrome. The purpose of the study is to compare L-dopa to a conventional antiparkinsonian medication ( procyclidine hydrochloride) and a placebo (lactose). Additionally, this study has been designed to determine whether a twoto six-week period is an adequate length of time to see the benefits of L-dopa therapy in parkinsonian patients receiving no other medication. It was also designed so that a patient could continue to take any drug that brought about significant improvement; in such cases, he was not required to try the other drugs in the study.