The effect of selegiline on the peripheral pharmacokinetics of levodopa in young volunteers

The plasma pharmacokinetics of levodopa were studied in eight healthy young subjects following an i.v. infusion of 50 mg over 5 min. Subjects were studied on two occasions in random order following treatment with carbidopa; on one occasion they were pretreated with selegiline (four doses of 10 mg over the preceding 3 days) and on the other with a placebo. The mean plasma concentration‐time curves on each occasion were essentially superimposable and there were no significant differences in any calculated pharmacokinetic parameter. Selegiline does not significantly alter the distribution or elimination of levodopa from plasma.