Hepatic disposition of alfentanil and sufentanil in patients undergoing orthotopic liver transplantation

Alfentanil and sufentanil are used in the anesthetic management of patients undergoing orthotopic liver transplantation (OLT) and are extensively metabolized by the liver. We examined the influence of OLT on the removal of these opioids. 14 patients undergoing OLT were given either alfentanil (40 mu g/kg intravenous [IV] bolus) or sufentanil (5 mu g/kg IV bolus) during the induction of anesthesia, followed by infusion during surgery (1 mu g.kg(-1).min(-1) alfentanil or 0.01 mu g.kg(-1).min(-1) sufentanil) and the postoperative period (0.5 mu g.kg(-1).min(-1) or 0.005 mu g.kg(-1).min(-1)). A catheter was inserted into the hepatic vein to determine the drugs' hepatic extraction coefficient and hepatic clearance. The hepatic extraction coefficient was 0.14 for alfentanil and 0.35 for sufentanil. The total and hepatic clearances of alfentanil were similar, while the hepatic clearance of sufentanil was 50% of the total clearance (P < 0.05). The total clearance of alfentanil was significantly linked to its hepatic clearance (r(2) = 0.81, P < 0.001). We conclude that the total clearance of sufentanil is greater than its hepatic clearance. This difference suggests that there is extrahepatic metabolism of sufentanil in patients undergoing OLT.