The present invention relates to compositions forming a low viscosity mixture of: i) a non-polymeric slow-release matrix ii) at least one biocompatible, (preferably oxygen containing) organic solvent iii) at least one peptide active agent and iv) at least one lipid soluble acid. The invention further relates to methods of treatment comprising administration of such compositions, especially in treating diabetes, and to pre-filled administration devices and kits containing the formulations.
