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Dopamine Agonists, MAO-B & COMT Inhibitors song

Dopamine Agonists, MAO-B & COMT Inhibitors, as a song. Hear the short teaser here. The full song is on YouTube and Spotify.

Dopamine Agonists, MAO-B & COMT Inhibitors

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Key points in this song10

Dopamine agonists (pramipexole, ropinirole, cabergoline) directly stimulate D2/D3 receptors and are used as monotherapy in early Parkinson's disease or adjuncts to levodopa to reduce motor fluctuations.
Dopamine agonists cause impulse control disorders (gambling, hypersexuality), hallucinations, and orthostatic hypotension — distinguishing side effects from levodopa.
Bromocriptine and cabergoline are ergot-derived dopamine agonists used for hyperprolactinemia and acromegaly; cabergoline is preferred due to fewer side effects but is associated with cardiac valvulopathy with long-term use.
MAO-B inhibitors (selegiline, rasagiline) selectively block monoamine oxidase type B, preventing dopamine breakdown in the striatum and extending levodopa's effect.
Selegiline is metabolized to amphetamine metabolites, which can cause insomnia; at high doses, MAO-B selectivity is lost, creating risk for serotonin syndrome especially with meperidine or SSRIs.
Rasagiline has neuroprotective claims and no amphetamine metabolites, making it better tolerated than selegiline in older patients.
COMT inhibitors (entacapone, tolcapone) block peripheral and central catechol-O-methyltransferase, preventing levodopa degradation and prolonging its half-life — always used with levodopa/carbidopa, never alone.
Entacapone acts peripherally only; tolcapone acts both centrally and peripherally but carries a risk of fatal fulminant hepatotoxicity requiring liver function monitoring.
COMT inhibitors reduce levodopa "wearing-off" phenomena by smoothing plasma levodopa levels, but can worsen dopaminergic side effects (dyskinesias, hallucinations, orthostasis).
The combination of levodopa/carbidopa/entacapone (Stalevo) is a fixed-dose formulation targeting end-of-dose motor fluctuations in Parkinson's disease management.