Neurology/Dopamine agonist

Dopamine agonists

also: ropinirole · pramipexole · rotigotine · apomorphine

Overview

Directly stimulate dopamine receptors — used to delay levodopa in younger patients, but impulse-control disorders are the defining adverse effect.

Mechanism

Directly agonise striatal dopamine D₂ receptors (bypassing the degenerating neurones). Non-ergot agents (ropinirole/pramipexole/rotigotine) are preferred over ergot agonists (fibrosis risk).

Indications

Parkinson's disease (early — to delay levodopa; or adjunct)
Restless legs syndrome
Prolactinoma/acromegaly (cabergoline/bromocriptine — cross-ref)

The agents

Ropinirole / pramipexolenon-ergot, oral

Impulse-control disorders; daytime somnolence/sudden sleep.

Rotigotinetransdermal patch

Useful when oral route unavailable.

ApomorphineSC (rescue)

Severe off periods.

Adverse effects

Impulse-control disordersserious

Gambling, hypersexuality, binge eating, shopping — ask directly + counsel patient/family.

Excessive daytime somnolence / sudden-onset sleepserious

Warn re driving.

Hallucinations (elderly), nausea, postural hypotensioncommon

Ergot agonists: cardiac/pulmonary/retroperitoneal fibrosisserious

Cautions & contraindications

Abrupt withdrawalall

Dopamine-agonist withdrawal syndrome / akinesia.

Caution in elderly / cognitive impairmentelderly

Hallucinations.

Interactions

Dopamine antagonists reduce effect

Monitoring & kinetics

Impulse-control review at each visit; somnolence; BP

Oral / patch / SC. Preferred to delay levodopa in younger patients.

Source: NICE NG71 — Parkinson's · BNF — Dopamine-receptor agonists