Clinical Question: What are the benefits and risks of monoamine oxidase type B inhibitors in patients with Parkinson’s disease?

Setting: Outpatient (any)

Study Design: Meta-analysis (randomized controlled trials)

Synopsis: The authors of this meta-analysis identified 17 randomized trials of patients with early Parkinson’s disease comparing one of the three monoamine oxidase type B inhibitors (i.e., selegiline, rasagiline, and the investigational lazabemide) with placebo, levodopa, or both. Patients with early Parkinson’s disease were defined as those without a history of motor complications who had not received treatment or who were treated for less than 12 months. The authors searched several electronic indexes and reference lists of retrieved publications, and hand searched abstracts and conference proceedings. The studies were abstracted independently by two reviewers and validated by a third reviewer. The authors did not report their method of judging which articles to include. Quality scores for the studies were not provided, but most (15 of 17) of the trials were double-blind, and only four studies used concealed allocation.

Most of the research (13 studies) evaluated selegiline. Clinical disability ratings were significantly better with use of selegiline in six of the studies. Also, the need for levodopa treatment was delayed significantly with early treatment with a monoamine oxidase type B inhibitor. By the end of the study period, the odds ratio comparing the need for levodopa between a monoamine oxidase type B inhibitor and placebo was 0.57 (95 percent confidence interval [CI], 0.48 to 0.67). The percentage of patients who received a 25 percent reduction in motor fluctuations was higher in the treated patients (odds ratio = 0.75; 95 percent CI, 0.59 to 0.95), although no difference occurred in the incidence of dyskinesia. Patients receiving a monoamine oxidase type B inhibitor were twice as likely to withdraw from therapy because of side effects as the patients receiving placebo. Mortality rates were not increased with treatment when the results of nine trials were combined.

Bottom Line: In patients with early Parkinson’s disease, treatment with a monoamine oxidase type B inhibitor—the most common being selegiline—improves disability scores and delays the need for levodopa without increasing mortality rates. Because only a few studies have compared this class of drug with other therapies, it is too early to prescribe selegiline for every patient with early Parkinson’s disease. (Level of Evidence: 1a)