[First pass effect by infusing 99mTc-human serum albumin into the hepatic artery]

The fundamental principles of intra-arterial infusion chemotherapy are thought to be increased local drug concentration and the "first-pass" effect. The concentration in the rest of the body can only be decreased if there is local elimination of the infused drug before reaching the systemic circulation. This is referred to as the "first-pass" effect. In the evaluation of "first-pass" effect, the uptake of liver after infusing 99mTc-human serum albumin (99mTc-HSA) in the hepatic artery by injecting the subcutaneously implanted silicon reservoir was compared with that obtained after intravenous administration of 99mTc-HSA. In order to remove the factor of portal infusion, each count of liver up take had been continued for only 24 seconds after starting the liver uptake. The results are as follows: for 24 cases excepting 6 cases with catheter obstruction, the mean i.a./i.v. ratio was 7.92 +/- 3.34 (range 3.25 to 17.25). Although the elimination rate of drugs in the liver varies with each drug, the infusion of intraarterial chemotherapy should be about 8 times more concentrative than intravenous administration on the "first-pass" effect.