Avibactam (NXL-104) free acid is a covalent and reversible inhibitor of non-β-lactam β-lactamase (IC50s: 8 nM and 5 nM for β-lactamase TEM-1 and CTX-M-15).
FPI-1523, a derivative of Avibactam, is a potent inhibitor of β-lactamase enzymes. It has Kd values of 4 nM and 34 nM for CTX-M-15 and OXA-48, respectively. Additionally, FPI-1523 inhibits PBP2 with an IC50 of 3.2 μM and demonstrates significant antimicrobial activity.