Which medication is used to counteract malignant hyperthermia?

Dantrolene is the medication used to counteract malignant hyperthermia, a serious reaction that can occur during or after anesthesia, particularly in response to certain anesthetic agents and muscle relaxants. Malignant hyperthermia is characterized by a rapid increase in body temperature and severe muscle contractions. Dantrolene works by inhibiting calcium release from the sarcoplasmic reticulum of skeletal muscle, thus reducing the hypermetabolic state associated with this condition.

The other medications listed are not suitable for this purpose. Propofol is an anesthetic agent used for induction and maintenance of anesthesia, rather than an antidote for malignant hyperthermia. Succinylcholine is a neuromuscular blocker that can actually trigger malignant hyperthermia in susceptible individuals. Thiopental is a barbiturate used for anesthesia induction but has no role in treating malignant hyperthermia. The specificity and effectiveness of dantrolene in addressing the pathophysiology of malignant hyperthermia make it the appropriate choice.