Avibactam-13C5,15N sodium (NXL-104-13C5,15N sodium) is the 13C- and 15N-labeled Avibactam (HY-14879). Avibactam (NXL-104) free acid is a covalent and reversible non-beta-lactam beta-lactamase inhibitor which inhibits beta-lactamase TEM-1 and CTX-M-15 with IC50s of 8 nM and 5 nM, respectively[1].