Influence of the routes of continuous intrahepatic infusion of 5-fluorouracil on its pharmacokinetics.

Continuous infusion chemotherapy via hepatic artery using newly available mechanical devices is frequently used to treat hepatic metastases to achieve a high concentration of 5-fluorouracil (5-FUra) in the hepatic circulation while minimizing systemic exposure. We compared four routes of intrahepatic administration to find out the best one in the canine model. To ascertain this data, 5-FUra (30 mg/kg) was given as a continuous infusion over a 3 hr period into either a systemic vein (femoral), portal vein, hepatic artery, or hepatic artery distal to its ligation after hepatic dearterialization. A total of eight dogs were studied. During 5-FUra infusion, concomitant blood samples were taken from the inferior vena cava and hepatic vein at 1, 2, 3, 5, 10, 15, 30, 60, 120, and 180 min. 5-FUra levels were determined in plasma by high-performance liquid chromatography. Blood flow in the portal vein and hepatic artery was measured by an electromagnetic flowmeter. The data described by a multicompartmental model, including the measured flows, had separate hepatic arterial and portal compartments with elimination from each described by linear kinetics. Mean area under the curve values in microgram/ml X min and the ratios of the systemic/hepatic vein areas following 5-FUra infusion via systemic, portal vein, hepatic artery, or hepatic artery after dearterialization routes were: 975/539 (R = 1.80), 939/748 (R = 1.35), 211/454 (R = 0.46), and 562/1,424 (R = 0.39). The results indicated that the administration of 5-FUra via the hepatic arterial route distal to its ligation results in the highest hepatic vein drug levels with the smallest systemic/hepatic vein exposure ratio, followed by intra-arterial route, while systemic and portal vein routes were not nearly as advantageous as the intra-arterial routes.