Adjunctive
cabergoline or placebo, in doses up to 5 mg daily, were administered to
Parkinson's disease patients with short-duration
levodopa responses in a 6-month double-blind trial. The 13 patients randomized to
cabergoline and completing the study had significantly improved Unified Parkinson's Disease Rating Scale (UPDRS) motor scores and timed hand-tapping test scores. Serial measurements on test days documented improved scores: (a) before the first
levodopa (and
cabergoline) dose of the day, (b) at the time of the peak
levodopa effect, and (c) at the end of the
levodopa response cycle, 5 h after test doses. Continued testing verified that these therapeutic responses were sustained for at least 48 h after the last
cabergoline dose. Patients randomized to placebo failed to improve on any of these measures. In a subsequent open-label dose-escalation phase, further improvement was documented as the dosage was gradually raised to 10 mg daily. As in the double-blind phase,
levodopa reduction allowed the improvement to occur in the absence of significantly increased
dyskinesias. Other side effects were more substantial with higher doses, however, including two of 11 patients with
hallucinations and
confusion. In summary, adjunctive single-daily-dose
cabergoline therapy resulted in long-lasting, dose-related improvement in
parkinsonism not seen in patients receiving placebo.