Nacubactam (OP0595 free acid) is a potent non-β-lactam-β-lactamase inhibitor with activity against class A and class C β-lactamases. Nacubactam (OP0595 free acid) acts as a penicillin binding protein (PBP) 2-active antibacterial, and gives β-lactamase-independent potentiation of β-lactams targeting other PBPs.

Nacubactam is a Phase 3-ready beta-lactamase inhibitor which works through multiple mechanisms of action, inhibiting a number of beta-lactamase enzymes as well as certain bacterial cell wall enzymes, lending the candidate a broad spectrum of activity when used in combination with beta-lactam antibiotics. In non-clinical studies, nacubactam-meropenem was shown to have potent antimicrobial activity against complicated urinary tract and severe respiratory tract infections, including those caused by meropenem-resistant strains, and against infections caused by CRE. In previously reported Phase 1 clinical studies, it was demonstrated that intravenous nacubactam was well tolerated among healthy volunteers when administered alone or in combination with meropenem. In these studies, nacubactam had no effect on ECG or vital signs parameters, and no trends in laboratory tests were observed. Pharmacokinetic studies in renal impaired patients and in cUTI patients have also been completed.