Dopamine Agonists & Other Parkinson's Drugs

When levodopa starts wearing off or a younger patient needs motor symptom relief without the early risk of dyskinesias, dopamine agonists step in — but they carry a side-effect profile that catches students off guard.

Dopamine agonists — pramipexole (Mirapex) and ropinirole (Requip) are the high-yield examples — directly stimulate dopamine receptors in the brain without needing conversion to dopamine. This bypasses the enzymatic pathway that levodopa depends on. They are used as monotherapy in early Parkinson's (especially in patients younger than 65 to delay levodopa and its long-term dyskinesias) or as adjuncts to levodopa in advanced disease to smooth out "off" episodes. Key adverse effects include orthostatic hypotension, daytime somnolence (patients may fall asleep suddenly, even while driving), nausea, and — critically — impulse control disorders such as compulsive gambling, shopping, binge eating, or hypersexuality. These behaviors can develop weeks to months into therapy and the patient may not self-report them. Nursing priorities: assess blood pressure lying and standing before and after dose initiation, teach the patient to change positions slowly, warn about drowsiness and driving risk, and specifically ask about new impulsive behaviors at every follow-up. Doses are titrated slowly upward. Abrupt discontinuation can trigger neuroleptic malignant-like syndrome (hyperthermia, rigidity, altered consciousness), so tapering is mandatory.

Key Distinctions

Don't confuse dopamine agonists (directly stimulate receptors) with levodopa (converted to dopamine centrally) — agonists bypass that conversion step entirely. Students often attribute impulse control disorders only to levodopa, but they are far more strongly associated with dopamine agonists. Sudden sleep attacks are unique to this drug class, not a general Parkinson's medication effect.

Clinical Pearl

Ask about gambling, not just tremors. Impulse control disorders are the signature side effect students forget — and the one NCLEX loves to test.