Which statement correctly describes the elimination of etomidate?
- A It undergoes spontaneous degradation in plasma to inactive products
- B It is hydrolysed rapidly by hepatic esterases to inactive metabolites, with less than 3 percent excreted unchanged ✓
- C It is N-demethylated by CYP450 to an active metabolite responsible for prolonged sedation
- D It is excreted almost entirely unchanged by the kidneys, so it accumulates in renal failure
Correct answer: B. It is hydrolysed rapidly by hepatic esterases to inactive metabolites, with less than 3 percent excreted unchanged
Explanation
Etomidate is cleared mainly by rapid hepatic ester hydrolysis to carboxylic acid derivatives that are pharmacologically inactive, and only a small fraction appears unchanged in urine. Clearance is high and exceeds hepatic blood flow somewhat, suggesting extrahepatic esterase contribution. Because the metabolites are inert, etomidate is suitable for continuous infusion without accumulation, unlike midazolam whose alpha-hydroxy metabolite is active. Spontaneous plasma degradation describes atracurium, not etomidate.
Reference: Morgan and Mikhail's Clinical Anesthesiology, 7th ed.
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