may cause renal problems especially in high doses in another salt from optimization study for the dibasic drug molecule u2212 erythro 2 amino 3 hydroxy 3 pyridin 4 yl 1 pyrrolidin 1 yl propan 1 one the dihydrochloride was the first salt prepared and characterized it was found to be hygroscopic and not well suited for development although it can be easily handled in the isolation on large scale the following counterions were used sulfuric acid 1 hydroxy 2 naphthoic acid methanesulfonic acid naphthalene 2 sulfonic acid benzenesulfonic acid l glutamic acid malonic acid citric acid u2212 l malic acid lactic acid ascorbic acid and acetic acid of these the pursuance of mono acetate the naphthalene 2 sulfonate and the 1 hydroxy 2 naphthoate salts were recommended however both the acetate and the naphthalene 2 sulfonate showed unsuitable behavior the acetate salt deliquesced at 51 rh and the naphthalene 2 sulfonate was difficult to scale up the latter salt also represented a large counterion compared to the base and especially at high doses this was perceived as a definite disadvantage in a third salt screening study the following counterions were used acetic acid l aspartic acid benzoic acid citric acid d gluconic acid d glucuronic acid hippuric acid hydrochloric acid u2212 l malic acid l lactic acid maleic acid l malic acid l mandelic acid 1 hydroxy 2 naphthoic acid oleic acid palmitic acid pamoic acid phosphoric acid saccharin stearic acid succinic acid sulfuric acid of these two salts the l mandelate and the stearate showed the most.