Avibactam sodium salt-13C5 (NXL-104-13C5) is 13C labeled Avibactam (sodium). Avibactam sodium (NXL-104) 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][2].