Tolcapone increases maximum concentration of levodopa

No significant increase of the maximum concentration (C-max) of levodopa af ter addition of catechol-O-methyltransferase inhibitor tolcapone occurred i n previous pharmacokinetic studies predominantly on healthy volunteers. We compared pharmacokinetics of levodopa in plasma before and after addition o f tolcapone in 13 treated parkinsonian subjects under standardized conditio ns. We found a significant increase of C-max of levodopa after the addition of tolcapone. This may represent one cause for the occurrence of dyskinesi a previously early in the course of treatment with tolcapone.