An aqueous parenteral pharmaceutical formulation of the IRM drug compound N-[4-(4-amino-2-ethyl-1-imidazo[4,5-]quinolin-1-y1)butyl]methanesulfonamide dissolved in water, buffer selected from citric acid, acetic acid, lactic acid, succinic acid, and tartaric acid, and optionally a tonicity adjuster, preferably selected from sorbitol and mannitol, wherein the pH is no greater than 6 and the formulation is sterile and preferably substantially free of sodium chloride.
