Effect of entacapone on plasma homocysteine levels in Parkinson's disease patients.

Peripheral metabolism of L-DOPA via enzyme catechol-O-methyltransferase (COMT) is one of the possible sources of homocysteine (HCY). The aim of this study was to assess plasma HCY levels in L-DOPA-treated Parkinson's disease (PD) patients and its influence by adding the inhibitor COMT (entacapone). Patients were divided into two groups: (1) patients long term treated with L-DOPA but were naïve to entacapone, (2) L-DOPA naïve patients, in whom a combined treatment with L-DOPA and entacapone was started. The HCY levels were higher in Group 1 than in Group 2. No statistically significant changes of HCY concentrations were found in both patient groups after adding entacapone to their L-DOPA treatments. Results of this study confirm that patients treated with L-DOPA for a long term have increased plasma HCY concentrations. We believe combined L-DOPA and entacapone therapy could be a possible protective mechanism against hyperhomocysteinemia in early PD.