Halothane, also known as fluothane, is a nonflammable, halogenated hydrocarbon and inhalational general anesthetic. Created in the 1950s by English chemist Charles Suckling after two years of research, halothane emerged as a safer alternative to ether and chloroform, which posed fire hazards in operating rooms. As “the first halogenated hydrocarbon volatile anesthetic used in clinical practice,” it transformed anesthesiology, though it has since been replaced by newer volatile anesthetics with improved safety profiles.
The drug’s chemical name is 2-bromo-2-chloro-1,1,1-trifluoroethane, and it stands as the sole nonether inhaled anesthetic in current use. This clear, colorless liquid possesses a sweet chloroform-like odor. Between 15-20 percent undergoes metabolism via the CYP2E1 enzyme, triggering immune responses that may cause hepatitis—a significantly higher metabolic rate compared to desflurane. Though its precise mechanisms remain incompletely understood, halothane likely binds to cholinergic potassium channels, NMDA receptors, and calcium channels, inducing neuronal hyperpolarization that prevents firing and produces anesthetic effects.
Halothane serves multiple surgical purposes, including anesthesia induction and maintenance by depressing nerve conduction, respiration, and cardiac contractility. Typically combined with agents like nitrous oxide, it achieves surgical anesthesia within 2-5 minutes. Its non-pungent odor facilitates induction better than aromatic alternatives, and it avoids stimulating salivary or bronchial secretions, reducing coughing. Postoperative nausea and vomiting incidence remains low. However, halothane exhibits greater cardiac output reduction than competing volatile anesthetics and demands calibrated vaporizers with careful monitoring to prevent overdose, despite possessing strong sedative properties without analgesic effects.
Halothane’s potentially severe adverse effects have diminished its clinical application. Its metabolites risk hepatic damage ranging from mild hepatitis to acute failure, especially with repeated short-interval exposures. Researchers advise against adult use due to hepatotoxicity risks. Additionally, halothane causes cardiorespiratory instability including hypotension, bradycardia, and arrhythmia; potentiates nondepolarizing muscle relaxants; increases malignant hyperthermia risk; and demonstrates slower induction and recovery compared to modern alternatives like isoflurane or desflurane.
In conclusion, halothane has been superseded despite originally replacing dangerous conventional anesthetics. While it effectively produces general anesthesia through nervous system inhibition, its elevated hepatotoxic risk from extensive metabolism, cardiorespiratory complications, and prolonged recovery make it inferior to contemporary options. Researchers should explore novel applications or combination therapies like disulfiram co-administration to mitigate liver damage risks.