Altered pharmacologic properties of liposome-associated human interferon-alpha. II.

Association of human interferon-alpha with multilamellar vesicles and reverse-phase evaporation vesicles resulted in altered retention and distribution of the interferon after injection into mice. Intramuscular injection of liposomal-interferon, after extrusion through 0.2 mu filters, resulted in significantly increased localized retention of interferon. Liposomal-interferon was retained locally from one to three days, depending on liposome composition, whereas an equivalent injection of free interferon was undetectable after 24 hrs. Intravenous injection of the liposomal-interferon preparations resulted in increased interferon levels in lung, spleen, and liver as compared to injection of free interferon. Preparation of small unilamellar vesicles in the presence of interferon revealed differences in modes of association of different species with the liposomes, based on differential titers on human vs. bovine cells.