Dopamine agonists

Dopamine agonists act on dopamine receptors themselves: they bind to and activate receptors of the D2 family (D2 and D3) in the striatum, standing in for the dopamine lost in Parkinson's disease and easing slowness, stiffness and tremor. How they relieve restless legs syndrome is not fully known, but it is thought to be through the same dopamine receptors. Pramipexole and ropinirole are non-ergot agonists.

• PramipexoleStarted early in Parkinson's disease, it delays motor complications compared with levodopa, but improves movement less.
• RopiniroleShares pramipexole's uses and warnings, but the liver (CYP1A2) clears it rather than the kidneys.

• Parkinson's disease
• Restless legs syndrome

• Drowsiness and sudden attacks of sleepKnown forSerious
• Compulsive gambling, shopping, eating or sexKnown forSerious
• Nausea and vomiting
• Hallucinations and confusionSerious
• Dizziness or fainting on standing
• Swollen legs and ankles
• Dyskinesia when added to levodopa
• Withdrawal: apathy, anxiety, low mood, pain
• Restless legs worsening over time (augmentation)

What the class has in common. Each drug's card has its own, and Known for marks what an exam expects you to know.

• Sleep attacks can come without warning, even while driving; sedatives and alcohol add to the drowsiness.
• People rarely volunteer impulse control problems, so patients and carers are asked about them directly.
• Antipsychotics and metoclopramide block dopamine receptors and weaken their effect.
• They are tapered, not stopped suddenly, to avoid withdrawal symptoms and a reaction like NMS.

Written for biofideX in plain words, after checking these references:

• Pramipexole dihydrochloride tablets: label (DailyMed)
• Ropinirole tablets: label (DailyMed)
• Ropinirole hydrochloride (NCI Thesaurus)
• Pramipexole: product information (EMA)
• Ropinirole (NHS)

For learning pharmacology, not for treatment decisions: no doses are given, and a prescriber, pharmacist or the product's own label is the word on any one patient. Spotted a mistake? Tell us and we'll correct it.