Which drug is an MAOI used in Parkinson's treatment?

• A. Selegiline
• B. Ropinirole
• C. Levodopa
• D. Rasagiline

Answer: (A)

Mao-B inhibitors work in Parkinson’s by blocking the breakdown of dopamine in the brain, which raises and prolongs dopamine signaling in the striatum. Selegiline is one of these drugs and acts as a selective MAO-B inhibitor at typical doses, meaning it primarily inhibits the enzyme that metabolizes dopamine in the brain rather than in the gut or liver. This increases available dopamine and helps improve motor symptoms, either on its own in milder disease or as an add-on to levodopa to extend its effect and reduce wearing-off.

Because it’s selective for MAO-B, the risk of dietary tyramine interactions is lower than with non-selective MAO inhibitors, though monitoring is still important. Rasagiline is another MAO-B inhibitor used in Parkinson’s, so the underlying concept is the same, but the option commonly highlighted in exams has historically been selegiline. Ropinirole is a dopamine receptor agonist, and levodopa is a dopamine precursor, so they do not fit the MAOI mechanism.