Avibactam sodium hydrate (NXL-104 hydrate) is a highly effective β-lactamase inhibitor that inhibits β-lactamases TEM-1 and CTX-M-15, as well as the carbapenemase produced by Klebsiella pneumoniae and carbapenem-resistant Enterobacteriaceae.

CTX-M-15:5 nM, TEM1:8 nM

Avibactam sodium hydrate is a covalent and reversible non-β-lactam β-lactamase inhibitor with IC50 values of 8 nM and 5 nM for the β-lactamases TEM-1 and CTX-M-15, respectively.[1]
Although Avibactam sodium hydrate has little or no antimicrobial activity, it effectively inhibits class A and C β-lactamases, and has no significant effect on the activities of metallo-β-lactamases and Fusobacterium oxysporum OXA carbapenemase. [2]
When Avibactam sodium hydrate was used in combination with ceftazidime (concentration range 0-256 mg/L), it inhibited the growth of 16 blaKPC-2-positive and 1 blaOXA-232-positive strains of K. pneumoniae with MIC50 and MIC90 of 8 mg/L.[4]

In a mouse model infected with K. pneumoniae Y8 strain, Avibactam sodium hydrate in combination with ceftazidime (0.375 mg/g; subcutaneous injection; every 8 hours for 10 days) significantly inhibited bacterial growth and demonstrated some therapeutic effect. [3]
After a single subcutaneous injection of Avibactam sodium hydrate (64 mg/kg), its estimated mean terminal half-life against Pseudomonas aeruginosa infection in a neutropenic mouse lung infection model was 0.24 hours. [3]