One-year open-label study of entacapone in patients with advanced Parkinson disease

A carboxy-O-methyl transferase inhibitor entacapone has been introduced as an adjuvant drug for Parkinson disease (PD) patients. Although clinical trials reported beneficial role of entacapone, a long-term trial over 3 years failed to show significant effect. The goals of this study were to evaluate the clinical benefit and the efficacy of entacapone in an open clinical practice.

After the completion of a double-blind placebo-controlled entacapone study, 149 patients from 4 centers were included. Antiparkinsonian medications were optimized by the judgment of the neurologists in charge. The clinical global impression (CGI) scale was obtained at 6 months and 1 year after the initiation of entacapone treatment.

Of the 149 patients, 117 patients chose to try entacapone in an open-label fashion. Sixty-nine (59%) patients completed the 1-year trial. Twenty-nine patients discontinued entacpaone before 6 months, and 19 between 6 months and 1 year during trial. Twelve patients out of 48 patients discontinued entacapone because of its poor efficacy. The CGI scale was 3.9 (+/-1.5) at the beginning of the trial, 4.3 (+/-1.1) at 6 month, and 3.8 (+/-1.3) at 1 year, respectively. The CGI scale of those who discontinued between 6 month and 1 year was 3.4 (+/-1.7), which was worse, but insignificantly, than that of the continuer.

The dropout at 1 year of our study was very high at 41%. Even though entacapone is indicated for advanced PD patients with motor fluctuation, the fluctuators commonly have dyskinesia and mental symptoms, which can become more troublesome with entacapone. In the patients with advanced PD, the clinical efficacy and side effects should be carefully considered in a long-term use of entacapone.