Key takeaways
Selegiline (Zelapar) and amantadine (Symmetrel) are both used to treat symptoms of Parkinson's disease (PD), but they work in different ways and belong to different drug classes. Selegiline is a monoamine oxidase type B (MAO-B) inhibitor that helps prevent the breakdown of dopamine in the brain, thereby extending the effects of levodopa. It is typically used as an add-on treatment for those already taking carbidopa/levodopa. On the other hand, amantadine is an N-methyl-D-aspartate (NMDA) antagonist that raises dopamine levels by blocking NMDA receptors, which helps relieve movement symptoms like trembling and stiffness. Amantadine can be used alone or with other PD medications. Selegiline is available in tablets, capsules, and orally disintegrating tablets (ODTs), while amantadine is available in oral form and as a solution for those who have trouble swallowing pills. Both medications can cause nausea and dizziness, but selegiline can cause high blood pressure if taken with tyramine-rich foods, while amantadine can lead to mood changes and hallucinations. Additionally, selegiline must be taken with caution to avoid serotonin syndrome if combined with certain medications, whereas amantadine requires careful monitoring for withdrawal symptoms if stopped suddenly.
