A DOSE-RANGING STUDY OF SELEGILINE IN PATIENTS WITH PARKINSONS-DISEASE - EFFECT ON PLATELET MONOAMINE-OXIDASE ACTIVITY

A dose-ranging study of selegiline was performed in patients with Park inson's disease to determine the minimal dosage of the drug able to in hibit greater than or equal to 95% of platelet monoamine oxidase (MAO) activity. Different doses of selegiline (5 or 10 mg daily, 10 or 20 m g weekly) were studied in four groups of six patients with Parkinson's disease. Platelet MAO activity was measured before and after 1 month' s treatment with selegiline. The doses of 5 or 10 mg daily and 20 mg ( i.e., 10 mg x 2) weekly induced a complete inhibition of platelet MAO- B activity from day 7 to day 28 (96.0-99.5%). In contrast, platelet MA O-B inhibition was only 75.9% of the basal value after a dosage of 10 mg weekly. These results demonstrate that 20 mg weekly is the minimal dosage of selegiline able to induce a maximal and long-lasting inhibit ion of platelet MAO-B activity in patients with parkinsonism. Further clinical trials are needed to investigate the clinical efficacy of thi s dose.