Effect of selegiline (deprenyl) on the progression of disability in early Parkinson's disease. Parkinson Study Group.

In patients with early, otherwise untreated Parkinson's disease, the abilities of selegiline (deprenyl) and tocopherol, antioxidative agents that act through complementary mechanisms, to delay the emergence of more severe disability requiring treatment with levodopa were evaluated. Eight hundred subjects were randomly assigned in a two-by-two factorial design to receive selegiline (10 mg per day), tocopherol (2000 IU per day), selegiline and tocopherol, or placebo and were followed up to determine the frequency of development of disability requiring treatment with levodopa, the primary end point. Interim analysis performed by an independent safety monitoring committee prompted a preliminary comparison of the 401 subjects assigned to tocopherol or placebo with the 399 subjects assigned to selegiline, alone or with tocopherol. During an average of 12 months of follow-up, only 97 subjects who received selegiline reached the end point. In contrast, 176 subjects who did not receive selegiline reached the end point during this period (P < 10(-8)). Selegiline was also found to be well tolerated and to have a small, but statistically significant symptomatic benefit. These results indicate that use of selegiline (10 mg per day) in patients with early, otherwise untreated Parkinson's disease, delays the emergence of more severe disability.