MOTOR EFFECTS OF THE PARTIAL DOPAMINE AGONIST (-)-3-(3-HYDROXYPHENYL)-N-N-PROPYLPIPERIDINE (PRECLAMOL) IN PARKINSONS-DISEASE

The motor effects of the partial dopamine agonist (-)-3-(3-hydroxyphen yl)-N-n-propylpiperidine [(-)-3-PPP, preclamol] were evaluated in nine patients with Parkinson's disease using a double-blind, placebo-contr olled design. (-)-3-PPP monotherapy had an antiparkinsonian effect in five of nine patients at a mean dose of 37 +/- 10 mg intramuscularly. The co-administration of(-)-3-PPP and a mildly dyskinetic dose of levo dopa, infused intravenously at steady-state, resulted in complete supp ression of dyskinesias and reemergence of parkinsonian signs in two of seven patients. These dopamine antagonist effects of(-)-3-PPP occurre d at relatively low (2.5 and 5 mg) doses. Our results suggest that par tial dopamine agonists can exert agonist or antagonist activity in par kinsonian patients depending on concurrent dopaminergic tone. Although this dual action of(-)-3-PPP and other partial agonists could be ther apeutically important on theoretical grounds, the small number of pati ents manifesting a clinically significant response and the frequently inconsistent effects could indicate that this class of agents may have relatively limited clinical utility.