Etomidate Adrenal Suppression — FRCA Primary MCQ

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EasyPharmacology - Intravenous AnaestheticsEtomidate Adrenal SuppressionFRCA Primary

Etomidate-induced adrenocortical suppression after an induction dose is primarily caused by inhibition of which enzyme?

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Correct answer: C — 11-beta-hydroxylase

Etomidate primarily inhibits adrenal 11-beta-hydroxylase (CYP11B1), reducing conversion of 11-deoxycortisol to cortisol. This produces reversible adrenocortical suppression and a reduced cortisol response to ACTH. The current UK SmPC states that suppression may last up to 8 hours after a single induction dose of 0.3 mg/kg. Monoamine oxidase is inhibited by MAO inhibitors; cyclooxygenase is inhibited by NSAIDs; alcohol dehydrogenase is inhibited by fomepizole; and acetylcholinesterase is inhibited by agents such as neostigmine and organophosphates. None of these explains the characteristic endocrine effect of etomidate.

Reference: B. Braun Medical. Etomidate 2 mg/ml emulsion for injection, Summary of Product Characteristics, section 5.1 Pharmacodynamic properties. Text revised 31 July 2024; emc updated 28 February 2025. https://www.medicines.org.uk/emc/product/15214/smpc