5-CNAC is an orally effective absorption enhancer with no inherent pharmacological activity. It significantly increases the gastrointestinal absorption efficiency of co-administered drugs (such as salmon calcitonin). By reversibly binding to peptide drugs in a non-covalent manner, 5-CNAC protects them from enzymatic degradation in the gastrointestinal tract and enhances lipid solubility, facilitating passive transepithelial transport without compromising intestinal epithelial integrity. It is useful in research as an adjuvant for oral peptide administration.