Inactivation of 5-fluorouracil by the liver during continuous regional and systemic infusion in pigs.

During continuous systemic or portal infusion of 5-fluorouracil (5-FU) to anaesthetized pigs, the cytostatic activity was reduced in blood traversing the liver. The liver eliminated between 15 and 50% of the amount 5-FU given per time unit. During jugular infusion the concentration of cytostatic compounds in portal blood was equal to or less than in systemic blood. The cytostatic activity was much higher in portal blood and lower in systemic blood during portal infusion. The findings speak in favour of portal infusions of 5-FU to patients with disseminated cancer in the liver.