Remifentanil's duration of action is due to metabolism by which mechanism?

Remifentanil's duration of action is due to metabolism by which mechanism?

• A. Spontaneous degradation in blood (Hoffman elimination)
• B. Hydrolysis by nonspecific plasma esterases
• C. Hydrolysis by pseudocholinesterase
• D. Urinary excretion

Answer: (B)

Remifentanil’s ultra-short duration comes from rapid inactivation by nonspecific plasma esterases. These esterases in the blood and tissues quickly hydrolyze the ester bond in remifentanil to inactive metabolites, so the drug is cleared very rapidly regardless of liver or kidney function. This esterase-mediated metabolism gives a consistently rapid offset, making the duration of action very short even after long infusions. Hoffmann elimination, the spontaneous degradation of certain drugs like atracurium and cisatracurium, explains why those agents dissipate without organ metabolism, but it does not apply to remifentanil. Hydrolysis by pseudocholinesterase would affect drugs such as succinylcholine or mivacurium, not remifentanil. Urinary excretion removes metabolites rather than being the primary mechanism of remifentanil’s rapid offset.

Remifentanil’s ultra-short duration comes from rapid inactivation by nonspecific plasma esterases. These esterases in the blood and tissues quickly hydrolyze the ester bond in remifentanil to inactive metabolites, so the drug is cleared very rapidly regardless of liver or kidney function. This esterase-mediated metabolism gives a consistently rapid offset, making the duration of action very short even after long infusions.

Hoffmann elimination, the spontaneous degradation of certain drugs like atracurium and cisatracurium, explains why those agents dissipate without organ metabolism, but it does not apply to remifentanil. Hydrolysis by pseudocholinesterase would affect drugs such as succinylcholine or mivacurium, not remifentanil. Urinary excretion removes metabolites rather than being the primary mechanism of remifentanil’s rapid offset.