SYNTEX INTERFERON LIPOSOME DELIVERY MONKEY STUDIES

Executive Summary

SYNTEX INTERFERON LIPOSOME DELIVERY MONKEY STUDIES indicate increased antiviral activity of the substance, Syntex Research Biochemistry Department head Deborah Eppstein reported at the first national meeting of the American Association of Pharmaceutical Scientists (AAPS) on Nov. 4 in Washington, D.C. Eppstein said that it was "encouraging that interferon was being released in a biologically active form and could have activity in the system against infection." The trial was designed to observe the systemic release and localized effects of liposome encapsulated interferons in African green monkeys infected with simian varicella virus. One day after the virus injections were given, treatments with free interferon-B and liposome interferon-B were started. The end result was that liposome interferon-B was found to give much better protection from a virus-induced rash than the free interferon-B, Eppstein maintained. The liposome delivery system is being studied to counter the side-effect profile from frequent dosing of interferons. Eppstein pointed out that "a mode of delivery that could reduce both the side effects as well as the frequency of administration of interferons would be desirable." Syntex is also performing lab work on a controlled-release mechanism for interferon. Eppstein presented results from a study in which interferon was encapsulated in bioerodable polymer matrices (PLGA) in order to obtain sustained release of a drug over a long period. In the controlled-release study, PLGA/interferon implants were placed subcutaneously into mice. "Such preparations resulted in a 2-3 month release profile of interferon in animals. . . [and it showed that] biodegradable sustained-release systems can be obtained without denaturing interferons, and can result in controlled-release profiles ranging from several days to a few months," Eppstein concluded. Liposome Technology, Inc. (LTI) is studying whether a sustained release formulation of liposome-encapsulated peptide hormone P-18 will remain biologically active in vivo. LTI senior peptide scientist Annie Yau-Young reported to the AAPS meeting on preclinical P-18 work. Rats were subcutaneously injected with P-18 and 60 minutes after the injection the rats were bled and serum was collected. Yau-Young reported that "P-18 in liposomes after encapsulation and processing were still biologically active" and it was found that over the 60-minute period only 10% activity could be observed which suggested that "90% of P-18 was still available for sustained release." Yau-Young maintained that "liposomes are suitable as carriers for macromolecular drugs due to the impermeability of the drug through the lipid bilayer" and some of the substances which can be carried effectively are hemoglobin, human growth hormone, insulin, catalase and C-reactive protein.