[Pharmacokinetics of human fibroblast interferon in rats].

Pharmacokinetic behaviors of human fibroblast interferon (HuIFN-beta) administered intravenously to rats were examined. After intravenous injection, plasma interferon level decreased in a biexponential fashion having the half-times of 15 min and 120 min respectively. Distribution levels of HuIFN-beta in the tissues at 30 min, though the actual concentrations were less than that of plasma, were observed according to the following order; kidney greater than adrenal greater than lung greater than spleen greater than liver greater than testis. Small amounts of HuIFN-beta were also detected in the thoracic lymph and bile but no HuIFN-beta was found in urine. The in vitro study indicated that the stability of HuIFN-beta was different in each tissue homogenates and body fluids. From the results obtained, we concluded that HuIFN-beta exhibited a low distributional character to the tissues when administered intravenously. It was also suggested that the kidney and the liver were the main catabolic sites of HuIFN-beta.