Clinical and pharmacological evaluation of the effects of piribedil in patients with parkinsonism.

Nine patients with Parkinsonism were studied before and after treatment with piribedil, a dopamine-receptor stimulator. Piribedil appeared to have a slight anti-Parkinsonism effect upon bradykinesia, and possibly upon tremor, but did not improve rigidity. The chief toxic effects were drowsiness and confusion, and two patients experienced nausea. Changes in homovanillic acid in the cerebrospinal fluid indicated that the drug reduced the turnover of endogenous dopamine. In spite of this definite neuropharmacological action, no clear-cut associated clinical benefit was demonstrated. The significance of these findings is discussed.