After identical 6-hour procedures, recovery is notably slower in a patient anaesthetised with halothane compared with one given desflurane. Which pharmacokinetic difference best accounts for this?

• A Halothane has a higher blood:gas partition coefficient alone
• B Halothane undergoes enterohepatic recirculation absent in desflurane
• C Halothane has a much higher fat:blood partition coefficient, causing accumulation and slow postoperative release from adipose tissue ✓
• D Halothane induces cytochrome enzymes that delay its own clearance

Explanation

During long procedures, highly fat-soluble agents accumulate in adipose tissue and continue diffusing back into blood after discontinuation, prolonging recovery. Halothane has a fat:blood coefficient of roughly 60, whereas desflurane's is about 27, so desflurane washes out rapidly even after prolonged administration. Blood solubility governs initial wash-in and early elimination, but tissue, especially fat, solubility dominates late recovery, which is why option A alone is incomplete.

Reference: Miller's Anesthesia, 9th ed.

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Written and medically reviewed by the StethoPrep medical team.