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Clonidine alpha-2 effects — FRCA Primary MCQ

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HardPharmacologyClonidine alpha-2 effectsFRCA Primary

A patient with chronic neuropathic pain receives clonidine as an adjunct during regional anaesthesia and becomes bradycardic with reduced anaesthetic requirement. Which receptor action explains this pattern?

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Correct answer: D — Central α2-adrenoceptor agonism

Clonidine is an α2-adrenoceptor agonist that reduces sympathetic outflow and anaesthetic requirements, but can cause bradycardia and hypotension. β2 agonism would produce a different cardiovascular and respiratory profile. Nicotinic antagonism and 5-HT3 antagonism do not explain analgesic adjunct effects. Dexmedetomidine shares this α2 mechanism with greater selectivity.

Reference: Peck, Hill & Williams Pharmacology for Anaesthesia and Intensive Care