HEPATIC DISPOSITION OF ALFENTANIL AND SUFENTANIL IN PATIENTS UNDERGOING ORTHOTOPIC LIVER-TRANSPLANTATION

Alfentanil and sufentanil are used in the anesthetic management of pat ients undergoing orthotopic liver transplantation (OLT) and are extens ively metabolized by the liver. We examined the influence of OLT on th e removal of these opioids. 14 patients undergoing OLT were given eith er alfentanil (40 mu g/kg intravenous [IV] bolus) or sufentanil (5 mu g/kg IV bolus) during the induction of anesthesia, followed by infusio n 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 h epatic vein to determine the drugs' hepatic extraction coefficient and hepatic clearance. The hepatic extraction coefficient was 0.14 for al fentanil 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 alfenta nil was significantly linked to its hepatic clearance (r(2) = 0.81, P < 0.001). We conclude that the total clearance of sufentanil is greate r than its hepatic clearance. This difference suggests that there is e xtrahepatic metabolism of sufentanil in patients undergoing OLT.