A patient with Parkinson's disease started on pramipexole (a dopamine agonist) reports episodes of falling asleep suddenly while driving without warning. This adverse effect is known as:

• A REM sleep behaviour disorder
• B Narcolepsy precipitated by pramipexole's adenosine blockade
• C Nocturnal enuresis from peripheral D2 receptor activation
• D Sudden onset sleep (sleep attacks), a recognised class effect of non-ergot dopamine agonists ✓

Explanation

Sudden onset sleep (sleep attacks) without prodromal sleepiness is a well-recognised, potentially dangerous adverse effect of dopamine agonists (pramipexole, ropinirole, cabergoline). Unlike simple somnolence, these attacks occur without warning and have been implicated in road traffic accidents. Patients on dopamine agonists must be counselled not to drive if they experience excessive daytime sleepiness. The mechanism is thought to involve direct D3 receptor-mediated sleep induction.

Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.

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Written and medically reviewed by the StethoPrep medical team.