Disclosed is a stable formulation for parenteral injection, as well as methods for its use and preparation, that includes a peptide or a salt thereof that has been previously dried from an aqueous composition comprising a partially volatile buffer, a volatile buffer, a strong acid, or a strong base, or any combination thereof, wherein the dried peptide or salt thereof has a first ionization profile that corresponds to the peptide's optimal stability and solubility, and an aprotic polar solvent, wherein the dried peptide or salt thereof is reconstituted into an aprotic polar solvent and has a second ionization profile in the aprotic polar solvent, wherein the first and second ionization profiles are substantially the same, such as within 1 pH unit of one another.
