Halothane

Halothane is a volatile anaesthetic gas, with many advantageous properties:

• potent at relatively low concentration
• smooth induction
• non-irritant
• pleasant to inhale
• causes bronchodilation

However, its use has declined as a result of a number of disadvantages:

• associated with severe hepatotoxicity:
  • severity of hepatotoxicity is increased by repeated exposure
  • halothane should not be used within 3 months of previous exposure
  • if the patient has had any episode of jaundice or pyrexia with halothane, it must never be administered again
  • in some series it accounts for some 5% of acute hepatic failure
• associated with cardiorespiratory depression, peripheral vasodilatation and sensitisation of the myocardium to catecholamines - elevated risk of arrhythmias
• little analgesia or muscular relaxation
• can imitate malignant hyperpyrexia