An anesthesiologist wants an opioid whose clearance is essentially unchanged no matter how long the intraoperative infusion runs, allowing rapid offset even after hours of administration. Which agent fits this requirement and why?

• A Alfentanil, because its small volume of distribution speeds elimination
• B Fentanyl, because its high lipid solubility permits rapid redistribution
• C Remifentanil, because it is hydrolyzed by ubiquitous blood and tissue esterases ✓
• D Sufentanil, because it undergoes rapid hepatic glucuronidation

Explanation

Remifentanil is an ester-linked opioid degraded by nonspecific plasma and tissue esterases, giving it a context-sensitive half-time of roughly 3 to 5 minutes that is nearly independent of infusion duration. This makes it ideal for continuous infusion without cumulative delay in recovery. It is not a substrate of pseudocholinesterase, so its offset is preserved even in pseudocholinesterase deficiency. Redistribution alone cannot prevent accumulation, which kills options B and A.

Reference: Katzung's Basic and Clinical Pharmacology, 15th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.