Hepatic and extrahepatic disposition of propofol in patients undergoing coronary bypass surgery.

In order to clarify the relative contribution of the liver to the short term disposition of propofol, hepatic blood flow was measured during induction of anaesthesia with an i.v. bolus dose of propofol 2 mg kg-1. Total clearance of the drug was 2390 (SD 340) ml min-1, hepatic extraction 82% and hepatic clearance 1060 (260) ml min-1. During the 60-min period of observation, hepatic extraction of propofol increased from 79% to 92%. It is concluded that, within 1 h, only 44% of the administered dose is removed by the liver. Consequently, drug accumulation may occur with repeated dosing or infusion of propofol. The increase in extraction results presumably from slow release of propofol from the soy-bean emulsion.