Halothane, sevoflurane are associated with which idiosyncratic reaction?

• A. Drug-induced liver injury
• B. Allergic reactions/hypersensitivity
• C. Toxic epidermal necrolysis (SJS)
• D. Malignant hyperthermia

Answer: (D)

Malignant hyperthermia is the idiosyncratic reaction associated with halothane and sevoflurane. This is a genetic, not immune-mediated, hypermetabolic disorder of skeletal muscle triggered by certain volatile anesthetics. In susceptible individuals, these agents cause an uncontrolled release of calcium from the sarcoplasmic reticulum via mutations in the ryanodine receptor (RYR1). The resulting calcium overload drives sustained muscle contraction and a rapid, global increase in metabolism, leading to dangerous hypercarbia, acidosis, hyperthermia, tachycardia, rhabdomyolysis, and hyperkalemia. Prompt recognition and treatment are crucial: stop the triggering agent, administer dantrolene to reduce calcium release, and provide supportive cooling and metabolic management. While halothane can be associated with idiosyncratic drug-induced liver injury in some contexts, the classic and most characteristic idiosyncratic reaction linked to these inhaled anesthetics is malignant hyperthermia.