Comparison of disappearance from blood and lymphatic delivery of human fibroblast interferon in rat by different administration routes.

Disappearance from the blood and lymphatic delivery of human fibroblast interferon (HuIFN-beta) in rats by the various administration routes were studied. Intravenous injection showed a rapid disappearance of HuIFN-beta from the blood circulation, however, the clearance rate was greatly decreased after 2 h and the half-lives were 15 min and 2.0 h. Intramuscular, subcutaneous and intraperitoneal injections maintained readily detectable levels in the blood for 12 h, and the half-lives were 2.3, 1.7 and 1.2 h, respectively. Lipid-surfactant mixed micelles greatly promoted the absorption of HuIFN-beta from the large intestine with extremely high selective lymphatic delivery, whereas intravenous and intramuscular injections showed no selective transfer into the lymphatics.