Etomidate inhibits adrenal steroidogenesis even after a single induction dose. The specific enzyme blocked is:
- A Cholesterol desmolase (CYP11A1) — conversion of cholesterol to pregnenolone
- B 3-beta hydroxysteroid dehydrogenase — conversion of pregnenolone to progesterone
- C 11-beta hydroxylase (CYP11B1) — conversion of 11-deoxycortisol to cortisol ✓
- D 17-alpha hydroxylase (CYP17A1) — conversion of pregnenolone to 17-OH pregnenolone
Correct answer: C. 11-beta hydroxylase (CYP11B1) — conversion of 11-deoxycortisol to cortisol
Explanation
Etomidate reversibly inhibits 11-beta hydroxylase (CYP11B1), the last step converting 11-deoxycortisol to cortisol in the zona fasciculata. A single induction dose suppresses cortisol synthesis for 6–12 hours in healthy adults and potentially longer in critically ill patients. This adrenocortical suppression is clinically relevant in septic patients where adequate cortisol response is essential for vasopressor sensitivity. Cholesterol desmolase (CYP11A1) is the rate-limiting step but is not the primary etomidate target.
Reference: Morgan & Mikhail's Clinical Anesthesiology, 6th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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