form of either a dry fill mixture of dry components or lyophilized product the solid dosage form may be conveniently and rapidly reconstituted with water or a sterile aqueous vehicle to provide at least a 5 mg ml true solution of m amsa having excellent stability characteristics preparation of the water soluble compositions of the present invention as a dry fill mixture may be accomplished by simply mixing the appropriate starting materials in the proper proportions thus the m amsa lactic acid composition is prepared by mixing m amsa base and d or l lactic acid in a ratio of about 1 5 to 4 moles of lactic acid per mole of m amsa a preferred embodiment comprises a mixture of about 1 5 to 2 5 moles of lactic acid per mole of m amsa preparation of the water soluble compositions as a lyophilized mixture may be accomplished by subjecting an aqueous solution of the appropriate starting materials in the proper proportions to a standard lyophilization process thus the lyophilized m amsa lactic acid product is prepared by forming an aqueous solution of m amsa and lactic acid d l or dl lactic acid in a ratio of from about 1 5 to 4 preferably 1 5 to 2 5 moles of lactic acid per mole of m amsa base and then lyophilizing said aqueous.