Comparing dopamine agonists in Parkinson's disease.

Dopamine agonists are effective in the management of both advanced and early-stage Parkinson's disease. Unfortunately, randomized head-to-head comparative studies between the many different dopamine agonists now available are sparse. Indirect comparisons of dopamine agonists show that ergot derivatives, such as pergolide and cabergoline, are as effective as non-ergot derivatives, such as ropinirole and pramipexole, in ameliorating Parkinson's disease symptoms in patients in early or advanced stages of the condition. As far as safety and tolerability are concerned, no significant differences between dopamine agonists are found. However, some specific adverse events, such as somnolence and sleep attacks, seem less frequent in monotherapy studies with pergolide than in those with the non-ergot dopamine agonists; however, because of the lack of direct-comparison studies this cannot be proved conclusively. Randomized, controlled comparative studies between dopamine agonists are necessary to verify any possible differences in their effectiveness and tolerability in the treatment of Parkinson's disease.