Monoamine oxidase inhibitors were considered potentially useful in the treatment of Parkinson disease, as blocking its breakdown could enhance dopamine transmission. However, nonselective monoamine oxidase inhibitors did not prove beneficial when given as monotherapy, and hypertensive crises were a problem. It was then discovered that selegiline, as a selective monoamine oxidase type B inhibitor, did not produce this reaction and was the first product in this category to be approved for the treatment of Parkinson disease. Rasagiline is a potent, second-generation, selective, irreversible monoamine oxidase type B inhibitor. Unlike selegiline, a drug for Parkinson disease with a similar mechanism of action, rasagiline is not metabolized to amphetamine derivatives. On February 22, 2005, the European Commission gave the final marketing authorization for rasagiline for the treatment of Parkinson disease. It is marketed in Europe as Azilect. It was approved by the Food and Drug Administration in the United States on May 17, 2006.