L-Alanyl-L-glutamine is a stable, highly soluble dipeptide composed of L-alanine and L-glutamine. It is a white crystalline powder with a molecular formula of C8H15N3O4. Its key feature is its stability in aqueous solution and resistance to heat sterilization, unlike free L-glutamine which is unstable. Its primary and most significant application is in clinical nutrition, specifically as a component of parenteral (intravenous) nutrition solutions. It serves as a crucial source of glutamine, a conditionally essential amino acid vital for immune function, intestinal mucosal integrity, and nitrogen balance in critically ill or surgical patients. By providing glutamine in this stable dipeptide form, it overcomes the solubility and stability limitations of free glutamine, making it a safe and effective pharmaceutical ingredient. Due to its role as a direct, metabolically active component in formulated injectable drugs, it is classified as a drug substance or active pharmaceutical ingredient (API) in parenteral nutrition products. It is also considered a novel functional excipient that enables the formulation of stable amino acid solutions. It is not typically used as a general-purpose chemical reagent or synthesis building block.