Clinical trial on the use of cytidine diphosphate choline in Parkinson's disease.

Thirty patients with Parkinson's disease, treated with levodopa for the past few years, concomitantly received 500 mg of cytidine diphosphate choline (CDPC) daily for 30 days. Significant improvements in some of the neurologic signs and in several electrophysiologic parameters measuring the traction reflex and the active contraction were observed. A greater stability of therapeutic response between doses of levodopa was also seen, although the incidence of dyskinesia increased. In a second stage of CDPC treatment, also lasting 30 days, the dose of levodopa was reduced by one-third, and the incidence of dyskinesia dropped to its previous level, but the therapeutic response remained stable. Addition of CDPC produced significant increases in plasma concentrations of dopa and homovanillic acid, with no modifications in tyrosine or 3-O-methyldopa concentrations. A significant increase in the number of lymphocytic dopaminergic receptors also occurred.