## Mechanism of Selegiline **Key Point:** Selegiline is a selective, irreversible inhibitor of monoamine oxidase-B (MAO-B), the enzyme responsible for dopamine catabolism in the brain. ### How It Works in Parkinsonism By inhibiting MAO-B, selegiline: 1. Prevents the breakdown of dopamine in the striatum 2. Increases synaptic dopamine concentration 3. Prolongs the effect of levodopa when used in combination 4. May slow disease progression (neuroprotective effect debated) **High-Yield:** Selegiline is selective for MAO-B at therapeutic doses (does not inhibit MAO-A), which means it does NOT cause the "cheese effect" (tyramine interaction) seen with non-selective MAO inhibitors. ### Clinical Use - Used as monotherapy in early Parkinson disease - Added to levodopa in advanced disease to reduce motor fluctuations - Typical dose: 5–10 mg/day - Metabolized to amphetamine and methamphetamine (minor metabolites, but may cause insomnia) **Clinical Pearl:** The neuroprotective claim (slowing disease progression) remains controversial; most evidence suggests symptomatic benefit rather than true disease modification.
Sign up free to access AI-powered MCQ practice with detailed explanations and adaptive learning.