Entacapone to tolcapone switch: Multicenter double-blind, randomized, active-controlled trial in advanced Parkinson's disease.

This double-blind study examined the efficacy and safety of replacing entacapone with tolcapone in fluctuating Parkinson's disease (PD) patients. Patients receiving entacapone for > or =15 days were randomly assigned to continue entacapone (n = 75) or switch to tolcapone (n = 75) and were followed up for 3 weeks. Efficacy measures included changes in on time (without disabling dyskinesia) and an investigator's global assessment (IGA). The on time increased by > or =1 hour/day (primary efficacy measure) in 43% of entacapone-treated patients and 53% of tolcapone-treated patients, and by > or =3 hours/day in 13% and 25%, respectively. The IGA indicated moderate/marked improvements in 25% of entacapone patients and 39% receiving tolcapone. Response rates (the proportion of patients with > or =1 hour/day increase in on time and improvements on IGA) were 17% with entacapone and 32% with tolcapone. Dyskinesia was the most common adverse event affecting 29% of entacapone and 31% of tolcapone recipients. One patient in each group had elevated liver enzymes, resulting in treatment withdrawal (levels returned to normal thereafter in both cases). In conclusion, within the limits of the protocol, there was a tendency for tolcapone to offer enhanced efficacy in patients with fluctuating PD, despite optimized entacapone therapy. Tolcapone can be considered, therefore, for patients whose motor fluctuations are inadequately controlled by their existing regimen.