Clinical pharmacokinetics of sevoflurane

Sevoflurane is a comparatively recent addition to the range of inhalational anaesthetics which has been recently released for clinical use, In compari son to older inhalational agents such as isoflurane or halothane, the most important property of sevoflurane is its low solubility in the blood. This results in a more rapid uptake and induction than the 'older' inhalational agents, improved control of depth of anaesthesia and faster elimination and recovery. The more rapid pharmacokinetics are a result of the low blood/ga s partition coefficient of 0.69, With an oil/gas partition coefficient of 4 7.2, the minimum alveolar concentration (MAC) of sevoflurane is 2.05%. Two to 5% of the drug taken up is metabolised by the liver. The pharmacokinetic s of sevoflurane do not change in children, obese patients or patients with renal insufficiency. The pharmacokinetics and pleasant odour of sevoflurane make mask induction feasible, which is an obvious advantage in paediatric anaesthesia, The hepa tic metabolism of sevoflurane results in the formation of inorganic fluorid e. Upon contact with alkaline CO2 absorbent, a small amount of sevoflurane is degraded and a metabolite (compound A) is formed and inhaled in trace am ounts. Whether inorganic fluoride or compound A are nephrotoxic is presentl y a matter of controversy.