Post of the Week: The DATATOP Study
Posted 25 November 2009 - 12:29 PM
The clinical efficacy of the selective MAO-B inhibitor, selegiline, alone and in combination with vitamin E (supposedly a naturally occurring free-radical scavenger) was evaluated in the DATATOP (Deprenyl and Tocopherol Antioxidative Therapy of Parkinsonism) clinical trial initiated in 1987 by the Parkinson Study Group (Parkinson Study Group 1989; Shoulson 1989; Macleod 2005). DATATOP specifically assessed whether chronic administration of selegiline plus vitamin E in 800 patients with early, untreated Parkinson’s disease might diminish “oxidative stress”, thereby slowing or even stopping disease progression and prolonging the time before levodopa therapy is required.
The initial analysis of the DATATOP trial data suggested that selegiline slowed the progression of disability significantly, as measured by the need for levodopa therapy (Shoulson 1989). Analysis at one year revealed that 176 of 401 (44%) patients in the placebo group but only 97 of 399 (24%) patients in the selegiline group had reached the “primary endpoint” (which is this study was the development of sufficient disability to require levodopa therapy). In fact, selegiline was found to reduce the risk for reaching the primary endpoint to approximately half of that of the placebo group (Lewitt 2004). However, these results were later attributed to modest yet significant symptomatic benefits of selegiline. This confounded any possible conclusion regarding neuroprotection. This symptomatic benefit became evident when the drugs were “washed out” and both groups were no longer found to have no significant clinical differences (Shoulson et al 2002).
Therefore, as far as we know, based on the DATATOP study, selegiline clearly has a modest symptomatic effect; vitamin E definitely does not slow disease progression in Parkinson’s disease; and, selegiline most likely does not slow disease progression either. Selegiline is currently FDA-approved as an adjunctive treatment to levodopa, especially for patients who are experiencing wearing off.
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