The present invention relates to mixtures comprising: i) at least one lipid and/or at least one oil; and ii) an alkyl ammonium EDTA salt; wherein the mixture has a water content in the range of 0 to 1.0 wt %. The invention further relates to mixtures which are pre-formulations, methods of treatment comprising administration of such pre-formulations, to pre-filled administration devices and kits containing the formulations, to the use of an alkylammonium EDTA salt to reduce the decomposition of the lipid components and/or any active agent contained within the pre-formulation, and to alkyl ammonium EDTA salts as described herein.