Effects of arginine in therapeutic protein formulations: a decade review and perspectives

Arginine (Arg) is a natural amino acid with an acceptable safety profile and a unique chemical structure. Arg and its salts are highly effective in enhancing protein refolding and solubilization, suppressing protein-protein interaction and aggregation and reducing viscosity of high concentration protein formulations. Arg and its salts have been used in research and 20 approved protein injectables. This review summarizes the effects of Arg as an excipient in therapeutic protein formulations with the focus on its physicochemical properties, safety, applications in approved protein products, beneficial and detrimental effects in liquid and lyophilized protein formulations when combined with different counterions and mechanism on protein stabilization and destabilization. The decade literature review indicates that the benefits of Arg overweigh its risks when it is used appropriately. It is recommended to add Arg along with glutamate as a counterion to high concentration protein formulations on top of sugars or polyols to counterbalance the negative effects of Arg hydrochloride. The use of Arg as a viscosity reducer and protein stabilizer in high concentration formulations will be the inevitable future trend of the biopharmaceutical industry for subcutaneous administration.