Preparation and properties of GnRH-loaded multilamellar liposomes

Binding of the decapeptide gonadotropin releasing hormone (GnRH) to multilamellar liposomes was investigated with variation of the lipid matrix and of the medium conditions. It is demonstrated, that binding capacity of liposomes may be varied within wide limits if negatively charged phosphatidic acid is made a constituent part of the liposomes. Binding to liposomes is protecting GnRH against enzymatic hydrolysis by proteases, if structural integrity of liposomes is maintained. These properties are in favour of the application of liposomes as a drug carrier system for GnRH. The determination of the binding capacity and of the association constant for a definite system GnRH/lipid and, additionally, comparison of these data with analogous results concerning substance P [Pharmazie 39, 765 (1984)] furnish some new information with respect to the interaction of oppositely charged peptides and lipids.