uch as aspartic acid and glutamic acid; aromatic acids such as benzoic acid and cinnamic acid; sulfonic acids such as p-toluenesulfonic acid or ethanesulfonicacid; or the like.If the inventive compound is an acid, the desired salt may be prepared by any suitable method known to the art, including treatment of the free acid with an inorganic or organic base, such as an amine (primary, secondary or