L-Lysine Monohydrochloride USP is the hydrochloride salt form of the essential amino acid L-lysine. It is a crystalline, highly soluble compound that provides a concentrated and stable source of lysine. As an essential amino acid, it plays a critical role in protein synthesis, calcium absorption, immune support, and collagen formation. Its USP grade ensures pharmaceutical and nutraceutical quality, making it widely used in clinical nutrition, fortified foods, and animal feed.