Pharmacology · Class
MAO-B inhibitors !
Drugs that slow the breakdown of dopamine in the brain. Modest benefit in Parkinson disease; watch for serotonergic and pressor drug interactions.
Updated 2026-11-01
What they are
Selegiline and rasagiline inhibit monoamine oxidase B irreversibly; safinamide inhibits it reversibly. They are used alone in early Parkinson disease or added to levodopa to shorten «off» time.
Mechanism of action
MAO-B is the main enzyme that oxidizes dopamine in the human striatum. Blocking it leaves more dopamine in the synapse. At usual doses they spare MAO-A in the gut and liver, so the dangerous tyramine «cheese reaction» of nonselective MAO inhibitors is much less likely, but selectivity is lost at higher doses.
Target: Monoamine oxidase B (MAO-B)
Drugs in this class
- RasagilineAn irreversible, selective MAO-B inhibitor for Parkinson disease, alone or with levodopa. No amphetamine metabolites…Monoamine oxidase B (MAO-B)
- SelegilineAn irreversible MAO-B inhibitor for Parkinson disease. It forms amphetamine metabolites and has serious interactions…Monoamine oxidase B (MAO-B)
- SafinamideA reversible MAO-B inhibitor added to levodopa for «off» episodes. It also reduces glutamate release; same interaction…Monoamine oxidase B (MAO-B)
Test yourself
Think of the answer, then tap the question to see it.
Which opioid is classically contraindicated with MAO-B inhibitors, and why?
Meperidine: the combination can cause stupor, rigidity, agitation and hyperthermia (serotonin toxicity).
Why do MAO-B inhibitors rarely cause the cheese reaction at usual doses?
Gut and liver MAO-A, which destroys dietary tyramine, stays active; selectivity is lost at higher doses.
Which MAO-B inhibitor produces amphetamine metabolites?
Selegiline (L-amphetamine and L-methamphetamine), which can cause insomnia and anxiety.
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed., ch. 21 (McGraw Hill, 2023); DailyMed - RASAGILINE tablet (DailyMed (U.S. National Library of Medicine), 2026); DailyMed - SELEGILINE HYDROCHLORIDE tablet (DailyMed (U.S. National Library of Medicine), 2026); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026).
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Representative model, for educational purposes only.