Cabergoline improves motor disability without modifying L-dopa plasma levels in fluctuating Parkinson's disease patients.

Studies on the influence of some dopamine agonists, particularly bromocriptine, on the pharmacokinetics of L-dopa have furnished contrasting results. Thus, any possible pharmacokinetic interaction should be taken into consideration when adding a new dopamine agonist to L-dopa treatment. In 12 Parkinson's disease (PD) patients with motor fluctuations, cabergoline was added in an 8-week study to their usual L-dopa/carbidopa therapy. Cabergoline was administered once a day at increasing doses of 0.5, 1, 2, and 3mg/day for a period of one week per dose, and 4mg/day for three weeks. Motor performance was assessed weekly evaluating the motor examination of the Unified Parkinson's Disease Rating Scale (UPDRS) and the patients' diaries of daily on-off time. Blood levels of both L-dopa and 3-O-methyldopa (3-OMD) were assayed by HPLC in two different days, over an 8-hour period, before initiating cabergoline and at the end of the study. The results of this study confirm that cabergoline is effective in the management of PD motor fluctuations without modifying L-dopa and 3-OMD pharmacokinetics.