Avycaz combines an older cephalosporin antibiotic, ceftazidime, and the β-lactamase inhibitor avibactam. Ceftazidime targets penicillin-binding proteins (PBPs) in the bacterial periplasm that are required for cell wall synthesis. Avibactam blocks β-lactamases (β-L) in the periplasm, which would otherwise inactivate the antibiotics resulting in drug resistance.