Arginine ionic properties

Unlike enantiomers, diastereomers have different solubilities in an achiral environment. Many chiral counterions, such as arginine and lysine, are commonly used to prepare salts of an ionic drug in order to improve its pharmaceutically relevant properties. However, when the drug is chiral, a chiral counterion should be used with caution. If the drug or the counterion is racemic, diastereomeric salts will be formed, constituting a heterogeneous system. Because the solubilities of diastereomers differ, a diastereomeric mixture of chiral salts is undesirable in a formulation. 

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