Etomidate causes adrenocortical suppression lasting 4–8 hours after a single induction dose. Which enzyme does it inhibit?
- A 17α-hydroxylase (CYP17A1)
- B 21-hydroxylase (CYP21A2)
- C 11β-hydroxylase (CYP11B1) ✓
- D 3β-hydroxysteroid dehydrogenase
Correct answer: C. 11β-hydroxylase (CYP11B1)
Explanation
Etomidate selectively and reversibly inhibits 11β-hydroxylase, the enzyme that converts 11-deoxycortisol to cortisol in the adrenal cortex. This suppresses basal and stress-induced cortisol synthesis for 4–8 hours following a single induction dose, which is clinically significant in septic and critically ill patients. 21-hydroxylase deficiency causes congenital adrenal hyperplasia. 17α-hydroxylase is involved in sex steroid synthesis; etomidate's primary clinical concern is cortisol, not androgen blockade.
Reference: Morgan & Mikhail's Clinical Anesthesiology, 6th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.