The present invention relates to compositions forming a low viscosity mixture of: a) at least one diacyl glycerol； b) at least one phosphatidyl choline； c) at least one oxygen containing organic solvent； d) at least one GnRH analogue； Wherein the pre-formulation forms, or is capable of forming, at least one liquid crystalline phase structure upon contact with an aqueous fluid. The invention further relates to methods of treatment comprising administration of such compositions, pre-filled administration devices and kits containing the formulations.
