The Effect of Entacapone on Levodopa Rate of Absorption and Latency to Motor Response in Patients With Parkinson Disease

Abstract

The aim of the study was to explore the potential effect of the catechol-O-methyltransferase inhibitor entacapone coadministration on the rate of absorption and matched latency to motor response of an oral test dose of levodopa/benserazide in the treatment of Parkinson disease (PD). Fourteen PD patients (Hoehn and Yahr stages 2-2.5) entered the study protocol. They underwent an oral levodopa instrumental kinetic-dynamic test on 2 occasions, 4 weeks apart, according to an intrasubject open comparative design: at the first examination, while receiving their usual levodopa/benserazide therapy, and at the second one after a 4-week entacapone (200 mg) dosing concomitantly with usual first morning levodopa/benserazide intake. Entacapone coadministration was associated with a median 15-minute lengthening (P < 0.05) of time to peak levodopa plasma concentration compared with levodopa/benserazide alone but failed to have a statistically significant effect on matched latency to drug motor effect. Levodopa peak plasma concentration was nearly identical in the 2 treatments. Overall, the delayed latency to single-dose peak plasma levodopa concentration on entacapone cotreatment was modest and of negligible clinical significance in a cohort of moderately affected PD patients.