New drug approved in fight against Parkinson's

The Food & Drug Administration has approved rasagiline (Azilect, Teva) for the treatment of Parkinson's disease (PD). Rasagiline is an irreversible monoamine oxidase type B (MAO-B) inhibitor that blocks the breakdown of dopamine, a chemical that transmits signals between the substantia nigra and other parts of the brain.

Parkinson's disease, a progressive, degenerative disorder of the central nervous system, is associated with trembling of the arms and legs, stiffness and rigidity of the muscles, and slowness of movement. These symptoms usually develop after the age of 60. It is estimated that 1.5 million Americans have PD, and an additional 50,000 people are diagnosed each year.

The product label states that rasagiline is contraindicated with the use of meperidine, as well as with other analgesics, St. John's wort, mirtazapine, and cyclobenzaprine. Teva recommends that patients undergoing elective surgery wait for at least two weeks after discontinuing rasagiline before undergoing surgery that requires general anesthesia. It is also recommended that patients avoid concomitant use of rasagiline with tricyclic antidepressants, selective serotonin reuptake inhibitors, or serotonin-norepinephrine reuptake inhibitors.

Teva recommends that patients avoid tyramine and amines while on rasagiline due to a possible hypertensive crisis/"cheese reaction," although MAO inhibitors that selectively inhibit MAO-B generally do not cause such a reaction. "Even though the interaction with tyramine and cheese is possible, rasagiline use at recommended therapeutic doses has not been associated with dietary tyramine challenges," noted Swanson. The product label, however, states that the selectivity of rasagiline at inhibiting MAO-B in humans has not been sufficiently established to allow rasagiline treatment without restrictions of tyramine and amines contained in medications.

Patients taking rasagiline showed a greater risk of melanoma than the general population. However, the FDA cannot establish that rasagiline is associated with an increased risk for melanoma. Some studies have shown that PD patients have a greater risk of developing melanoma compared with the general population. To address whether rasagiline itself increases the risk of melanoma, Teva will perform a phase IV study.