halothane

Halothane is a volatile inhalational general anesthetic that has historically been used to induce and maintain anesthesia in humans and animals. It is a halogenated ether with the chemical name 2-bromo-2-chloro-1,1,1-trifluoroethane (C2HBrClF3). Known for its relatively pleasant odor, halothane is administered by inhalation through a calibrated vaporizer and is typically used in combination with oxygen or nitrous oxide. It is non-flammable and has a moderate onset and recovery profile, partly due to its relatively high blood-gas partition coefficient.

Pharmacologically, halothane acts by broad modulation of neuronal excitability, including potentiation of GABA-A receptor activity and other effects on membrane and receptor function that reduce neuronal firing. Volatile anesthetics, including halothane, have a non-specific mechanism and may also depress respiration and cardiovascular function. Halothane is metabolized in the liver to reactive trifluoroacetylated compounds, and a portion of the dose is converted to metabolites that can, in rare cases, contribute to immune-mediated hepatitis. The drug can sensitize the heart to catecholamines, increasing the risk of arrhythmias, and like other inhaled agents, can precipitate malignant hyperthermia in susceptible individuals.

Historically, halothane was widely used from the 1950s through the late 20th century. Its use has declined in many countries due to concerns about hepatotoxicity and the availability of safer, more economical alternatives such as isoflurane, sevoflurane, and desflurane. It remains of historical importance in the development of modern anesthesia and in veterinary practice.