MAO-B is generally believed to break down  dopamine; however, recent evidence suggests that MAO-A may mostly or entirely be responsible for dopamine metabolism. Rasagiline prevents the breakdown of dopamine by irreversibly binding to MAO-B. Dopamine is therefore more available, somewhat compensating for the diminished quantities made in the brains of people with Parkinsons.Selegiline was the first selective MAO-B inhibitor. It is partly metabolized to levomethamphetamine (l-methamphetamine), one of the two enantiomers of methamphetamine, in vivo. While these metabolites may contribute to selegilines ability to inhibit reuptake of the neurotransmitters dopamine and norepinephrine, they have also been associated with orthostatic hypotension and hallucinations in some people. Rasagiline metabolizes into 1(R)-aminoindan which has no amphetamine-like characteristics and has neuroprotective properties in cells and in animal models.It is selective for MAO type B over type A by a factor of fourteen. Metabolism
Rasagiline is broken down via CYP1A2, part of the cytochrome P450 metabolic path in the liver. It is contraindicated in patients with hepatic insufficiency and its use should be monitored carefully in patients taking other drugs that alter the normal effectiveness of this metabolic path. History
Racemic rasagiline was discovered and patented by Aspro Nicholas in the 1970s as a drug candidate for treatment of hypertension.Moussa B. H. Youdim, a biochemist, had been involved in developing selegiline as a drug for Parkinsons, in collaboration with Peter Reiderer.
When taken with L-DOPA, side effects include increased movement problems, accidental injury, sudden drops in blood pressure,  joint pain and swelling, dry mouth, rash, abnormal dreams and digestive problems including vomiting, loss of appetite, weight loss, abdominal pain, nausea, constipation. When taken with Parkinsons drugs other than L-DOPA, side effects include peripheral edema, fall, joint pain, cough, and insomnia. Interactions
People who are taking meperidine, tramadol, methadone, propoxyphene, dextromethorphan, St. John’s wort, cyclobenzaprine, or another  MAO inhibitor should not take rasagiline.The FDA drug label carries a warning of the risk of serotonin syndrome when rasagiline is used with antidepressants or with meperidine. However the risk appears to be low, based on a multicenter retrospective study in 1504 people, which looked for serotonin syndrome in people with PD who were treated with rasagiline plus antidepressants, rasagiline without antidepressants, or antidepressants plus Parkinsons drugs other than either rasagiline or selegiline; no cases were identified.There is a risk of psychosis or bizarre behavior if rasagiline is used with dextromethorphan and there is a risk of non-selective MAO inhibition and hypertensive crisis if rasagiline is used with other MAO inhibitors. Chemistry
Rasagiline is molecularly a propargylamine derivative. The form brought to market by Teva and its partners is the mesylate salt, and was  designated chemically as: 1H-Inden-1-amine-2,3-dihydro-N-2-propynyl-(1R)-methanesulfonate. Pharmacology
Mechanism of action
Parkinsons disease is characterized by the death of cells that produce dopamine, a neurotransmitter. An enzyme called monoamine oxidase (MAO) breaks down neurotransmitters. MAO has two forms, MAO-A and MAO-B.