Pharmacology  ·  Antiparkinson Drugs

Dopamine Agonists

Drug class overview, agents, and adverse effect profile

• Dopamine agonists act directly on striatal dopamine receptors without requiring conversion — their longer half-lives provide more continuous receptor stimulation than levodopa, making them useful for reducing motor fluctuations and as initial monotherapy in younger patients.
• The preferred agents are non-ergot agonists (pramipexole, ropinirole, rotigotine) — ergot-derived bromocriptine carries fibrosis risk and is no longer preferred; rotigotine's transdermal patch provides the most continuous delivery of the oral/patch agents.
• Apomorphine is a subcutaneous injection D1/D2 agonist reserved for acute rescue of severe off episodes — its 10–20 minute onset is the fastest available, but it is highly emetogenic and requires antiemetic pretreatment with trimethobenzamide; ondansetron is contraindicated due to severe hypotension risk.
• Impulse control disorders (compulsive gambling, hypersexuality, compulsive eating) are a class-defining adverse effect driven by D3 mesolimbic activation — patients rarely volunteer this history and must be asked directly at every visit.
• Sleep attacks — sudden-onset sleep without warning — are more prominent with dopamine agonists than with levodopa; patients must be counseled not to drive until they understand their individual response.