Rasagiline mesylate is primarily used in the treatment of Parkinson's disease. It functions as a selective and irreversible monoamine oxidase-B (MAO-B) inhibitor, which helps to increase dopamine levels in the brain. This action alleviates symptoms such as tremors, stiffness, and bradykinesia, improving motor function and overall quality of life for patients. It can be used as a monotherapy in early-stage Parkinson's or as an adjunct to levodopa in more advanced cases. Additionally, it may have neuroprotective properties, potentially slowing disease progression, though this is still under research. Its once-daily dosing offers convenience and enhances patient compliance.