Definition
ChEBI: A member of the class of azabicycloalkanes that is (2S,5R)-7-oxo-1,6-diazabicyclo[3.2.1]octane-2-carboxamide in which the amino hydrogen at position 6 is replaced by a sulfooxy group. Used (in the form of its sodium salt)
n combination with ceftazidime pentahydrate for the treatment of complicated urinary tract infections including pyelonephritis.
Enzyme inhibitor
This non-β-lactam inhibitor of β-lactamase (FW = 261.27 g/mol; CAS 1192500-31-4), also known as NLX104 and AVE1330A, shows a spectrum of action against Classes A and C β-lactamase as well as selected Class D β-lactamase, enzymes that often confer resistance to β-lactam antibiotics. By forming a high-affinity complex with its target enzymes, avibactam enhances the antibacterial activity of certain β-lactam drugs, such as ceftaroline. With over 1000 known β-lactamase, the action of avibactam is apt to depend on the invidual active-site interactions. Mode of Action: Acylation and deacylation rates have been measured for the clinically important enzymes CTX-M-15, KPC-2, E. cloacae AmpC, P. aeruginosa AmpC, OXA-10, and OXA-48. The efficiency of acylation (kon/Ki) varies across the enzyme spectrum, from 1.1 x 101 M–1 s –1 for OXA-10 to 1.0 x 105 M–1 s –1 for CTX-M-15. Inhibition of OXA-10 was shown to follow a reversible covalent mechanism (see below), and the acylated OXA-10 displayed the longest residence time for deacylation, with a half-life of greater than 5 days. The inhibited enzyme forms are stable to hydrolysis for all enzymes with the exception of KPC-2, which displays slow hydrolytic route that involved fragmentation of the acyl-avibactam complex. In the case of TEM-1 lactamase, avibactam slowly covalently acylates its target, and the acylated enzyme subsequently undergoes slow deacylation (koff = 0.045 min?1 ) regenerating avibactam intact. Use as a Combined Drug: Combination of avibactim with extended-spectrum cephalosporins or aztreonam shows promise in inhibiting Klebsiella pneumoniae (KP) isolates harboring carbapenemases, or KPCs. Given abundant experience with ceftazidime and the significant improvement avibactam provides against contemporary β-lactamase-producing Gram-negative pathogens, this combination will likely play a role in the treatment of complicated urinary tract infections (as monotherapy) and complicated intra-abdominal infections (in combination with metronidazole) caused (or suspected to be caused) by otherwise resistant pathogens, such as extended spectrum β-lactamase-, AmpC-, or Klebsiella pneumoniae carbapenemase producing Enterobacteriaceae and multidrug-resistant P. aeruginosa.
