Which inhalant anesthetic is hepatically metabolized up to about 25% and can sensitize the heart to catecholamines?

• A. Desflurane
• B. Halothane
• C. Sevoflurane
• D. Isoflurane

Answer: (B)

Halothane fits both points: it is the inhaled anesthetic with the notable level of hepatic metabolism, and it is the one known to sensitize the heart to catecholamines. About 20–25% of halothane is metabolized by the liver, and this metabolic process can produce reactive metabolites that contribute to hepatotoxicity and hepatitis in some patients. At the same time, halothane can make the myocardium more sensitive to catecholamines, so administering epinephrine or experiencing high endogenous catecholamine levels can trigger arrhythmias. The other commonly used inhalants have far less hepatic metabolism and do not appreciably sensitize the heart to catecholamines, so halothane is the best match for these two features.