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Keywords:

  • Parkinson's disease;
  • (-)-3–PPP;
  • Preclamol;
  • Partial dopamine agonist;
  • Dyskinesias

Abstract

The motor effects of the partial dopamine agonist (–)-3-(3-hydroxyphenyl)-N-n-propylpiperidine [(–)-3-PPP, preclamol] were evaluated in nine patients with Parkinson's disease using a double-blind, placebocontrolled 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 levodopa, infused intravenously at steady-state, resulted in complete suppression of dyskinesias and reemergence of parkinsonian signs in two of seven patients. These dopamine antagonist effects of (–)-3-PPP occurred at relatively low (2.5 and 5 mg) doses. Our results suggest that partial dopamine agonists can exert agonist or antagonist activity in parkinsonian patients depending on concurrent dopaminergic tone. Although this dual action of (–)-3-PPP and other partial agonists could be therapeutically important on theoretical grounds, the small number of patients manifesting a clinically significant response and the frequently inconsistent effects could indicate that this class of agents may have relatively limited clinical utility.