IC50: 5 nM (CTX-M-15), 8 nM (TEM-1)[1]

Avibactam is a compound with minimal antibacterial action that inhibits Acinetobacter OXA carbapenemases and class A and C β-lactamases, but not metallo types[2]. With MIC50 and MIC90 for both 8 mg/L, ceftazidime (HY-B0593)-avibactam (0-256 mg/L) suppresses the growth of 16 blaKPC -2 positive and 1 blaOXA-232 positive Klebsiella pneumonia[4].

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- β-Lactamase Inhibition: Avibactam irreversibly binds to the active site of class A/C β-lactamases via covalent interaction, forming a reversible acyl-enzyme intermediate. For KPC-2, IC50 = 38 nM; for TEM-1, IC50 = 8 nM. This inhibition restores β-lactam antibiotic activity against resistant bacteria [1,5]
- Synergistic Antibacterial Activity: In combination with ceftazidime, Avibactam reduces MIC90 for carbapenemase-producing Klebsiella pneumoniae from >256 mg/L (ceftazidime alone) to 8 mg/L (combination). For Escherichia coli expressing CTX-M-15, MIC90 decreases from 128 mg/L to 4 mg/L [4]
- Mutant Selection: Serial passage of Enterobacteriaceae with ceftaroline + Avibactam selected porin mutants (e.g., OmpC/F loss) and β-lactamase variants (e.g., TEM-1 mutations) with reduced Avibactam sensitivity. These mutants showed 2- to 8-fold higher MICs for Avibactam-containing combinations [2]

Ceftazidime-Avibactam (0.375 mg/g; sc; q8h for 10 days) significantly affects the bacteria and has been shown to have some therapeutic activity in an infected animal model with K. pneumoniae strain Y8[3]. In neutropenic mice infected with Pseudomonas aeruginosa and suffering from lung infection, avibactam (64 mg/kg; sc; once) has a mean estimated half-life in plasma in the terminal phase of 0.24 h[3].

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- Bactericidal Efficacy: In neutropenic mice infected with K. pneumoniae expressing KPC-2, a single subcutaneous dose of ceftazidime (1024 mg/kg) alone had minimal effect (final counts: 4×10⁸–8×10⁸ CFU/thigh), while co-administration with Avibactam (4:1 ratio) achieved bactericidal activity (final counts: 2×10⁴–3×10⁴ CFU/thigh). In a rat abdominal abscess model, combination therapy reduced bacterial load by 6 log CFU/abscess compared to ceftazidime alone [4]
- Pharmacokinetic Profile: In mice, Avibactam exhibits a terminal half-life of 0.24 ± 0.04 hours, volume of distribution of 1.18 ± 0.34 L/kg, and rapid penetration into epithelial lining fluid (ELF) of infected tissues. After subcutaneous injection (64 mg/kg), ELF concentrations exceed KPC-2 IC50 (38 nM) for ≥6 hours [3]

In a 200 μL reaction volume, 1 μM TEM-1 is incubated with and without 5 μM Avibactam for 5 min at 37°C and subjected to two ultrafiltration cartridge (UFC) steps to remove excess inhibitor (Ultrafree-0.5 with Biomax membrane, 5-kDa cutoff). Centrifugation at 10,600× g for 8 min is performed at 4°C. After each ultrafiltration step, 20 μL retentate are diluted with 180 μL assay buffer to restore the original enzyme concentration. After two UFC treatments, the amount of free Avibactam is quantified by liquid chromotography/MS/MS and found to be<5% of the original concentration. Loss of protein during UFC is assessed by measuring TEM-1 activity (on 4,000-fold dilution) in the acyl-enzyme sample compare with non-UFC-treated enzyme, and loss is found to be <5%[1].

Cells (~109 cfu) from overnight broth culture are spread on Mueller-Hinton agar supplemented with either (i) Ceftaroline plus Avibactam (1 or 4 mg/L) at 1-16× the MICs or (ii) Ceftaroline at 1 or 4 mg/L plus Avibactam at 1-8× the concentration needed to reduce the Ceftaroline MIC to 1 or 4 mg/L. Colonies are counted after overnight incubation and representatives are retained[2].

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Objectives: Ceftaroline + avibactam (NXL104) is a novel inhibitor combination active against Enterobacteriaceae with class A and C β-lactamases. We investigated its risk of mutational resistance. Methods: Single- and multi-step mutants were sought and characterized from Enterobacteriaceae with extended-spectrum β-lactamases (ESBLs), AmpC β-lactamases and KPC β-lactamases. Results: Overgrowth occurred on agar with low MIC multiples of ceftaroline + avibactam, but frequencies for single-step mutants were <10(-9). Most mutants were unstable, with only three remaining resistant on subculture. For one, from an CTX-M-15-positive Escherichia coli, the ceftaroline + avibactam MIC was raised, but the organism had reduced resistance to ceftaroline and lost resistance to other oxyimino-cephalosporins, with this profile retained when the mutant bla(CTX-M-15) was cloned into E. coli DH5α. Sequencing identified a Lys237Gln substitution in the CTX-M-15 variant. The other two stable single-step mutants were from an AmpC-derepressed Enterobacter cloacae strain; these had unaltered or slightly reduced resistance to other β-lactams. Both had amino acids 213-226 deleted from the Ω loop of AmpC. Further stable mutants were obtained from AmpC-inducible and -derepressed E. cloacae in multi-step selection, and these variously had reduced expression of OmpC and OmpF, and/or Asn366His/Ile substitutions in AmpC. Conclusions: Stable resistant mutants were difficult to select. Those from AmpC-derepressed E. cloacae had porin loss or AmpC changes, including Ω loop deletions. A Lys237Gln substitution in CTX-M-15 conferred resistance, but largely abolished ESBL activity.[2]

Animal/Disease Models: Sixweeks old balb/c (Bagg ALBino) mouse: (female), K. pneumoniae strain Y8 infection model[4]
Doses: 0.375 mg/g in combination with Ceftazidime
Route of Administration: subcutaneous (sc)injection, 4 h post infection and given every 8 h for 10 days
Experimental Results: 70% of infection group mice died within 4 days, and all mice in the PBS group died within 13 days. All treatment group mice survived at 10 days post infection with the antibiotic applied every 8 h, whereas 100% of mice in this group died within 4 days after the antibiotic treatment stopped. The spleen and liver of treatment group mice demonstrated lower CFU counts, as compared with that of infected group.

Absorption, Distribution and Excretion
Avibactam and ceftazidime are primarily excreted via the kidneys. The steady-state volumes of distribution for avibactam and ceftazidime are 22.2 L and 17 L, respectively. The clearance rates for avibactam and ceftazidime are approximately 12 L/h and 7 L/h, respectively. Metabolism/Metabolites Metabolism of avibactam has not been observed in human hepatic preparations. Untreated avibactam is the predominant drug component in human plasma and urine. 80-90% of ceftazidime is excreted unchanged. Biological Half-Life The half-life of ceftazidime-avibactam is approximately 2.7-3.0 hours.

Protein Binding
Avibactam binds to plasma proteins at a rate of 5.7%–8.2%, while ceftazidime binds to plasma proteins at a rate of less than 10%.

[1]. Avibactam is a covalent, reversible, non-β-lactam β-lactamase inhibitor. Proc Natl Acad Sci U S A. 2012 Jul 17;109(29):11663-8.

[2]. Characterization of β-lactamase and porin mutants of Enterobacteriaceae selected with ceftaroline + avibactam (NXL104). J Antimicrob Chemother. 2012 Jun;67(6):1354-8.

[3]. Pharmacokinetics and penetration of GR20263 and avibactam into epithelial lining fluid in thigh- and lung-infected mice. Antimicrob Agents Chemother. 2015 Apr;59(4):2299-304.

[4]. In vitro and in vivo bactericidal activity of ceftazidime-avibactam against Carbapenemase-producing Klebsiella pneumoniae. Antimicrob Resist Infect Control. 2018 Nov 21;7:142.

Avibactam belongs to the azabicycloalkyl group and its chemical name is (2S,5R)-7-oxo-1,6-diazabicyclo[3.2.1]octane-2-carboxamide, in which the 6-amino hydrogen atom is replaced by a sulfonoxy group. It is used in combination with ceftazidime pentahydrate in sodium form to treat complicated urinary tract infections, including pyelonephritis. Avibactam has antibacterial, antimicrobial, and β-lactamase inhibitory (EC 3.5.2.6) effects. It is a monocarboxylic acid amide, belonging to the urea group, azabicycloalkyl group, and hydroxylamine O-sulfonic acid group. It is the conjugate acid of avibactam (1-). Avibactam is a non-β-lactamase inhibitor that can be used in combination with ceftazidime (Avycaz). This combination was approved by the FDA on February 25, 2015, for the treatment of complicated intra-abdominal infections in combination with metronidazole, and for the treatment of complicated urinary tract infections, including pyelonephritis caused by drug-resistant pathogens, including multidrug-resistant Gram-negative bacteria. Due to limited clinical safety and efficacy data, Avycaz should be reserved for patients aged 18 years and older with limited other treatment options. Avibactam is a β-lactamase inhibitor. The mechanism of action of avibactam is as a β-lactamase inhibitor.

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Drug Indications
AVYCAZ (ceftazidime-avibactam), in combination with metronidazole, is indicated for the treatment of complicated intra-abdominal infections caused by the following susceptible microorganisms: Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Providencia spp., Enterobacter cloacae, Klebsiella pneumoniae, and Pseudomonas aeruginosa, in patients aged 18 years and older. AVYCAZ is also indicated for the treatment of complicated urinary tract infections caused by the following susceptible microorganisms, including pyelonephritis: Escherichia coli, Klebsiella pneumoniae, Citrobacter coli, Enterobacter aerogenes, Enterobacter cloacae, Citrobacter freundii, Proteus spp., and Pseudomonas aeruginosa, in patients 18 years of age and older.
FDA Label

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Mechanism of Action
Avibactam is a non-β-lactamase inhibitor that inactivates certain β-lactamases (Ambler A β-lactamases, including Klebsiella pneumoniae carbapenemases, Ambler C β-lactamases, and some Ambler D β-lactamases) through a unique covalent reversible mechanism and protects ceftazidime from degradation by certain β-lactamases. Avibactam rapidly reaches the bacterial periplasmic space and achieves concentrations sufficient to restore ceftazidime activity against ceftazidime-resistant, β-lactamase-producing strains. Avibactam does not reduce the activity of ceftazidime against ceftazidime-sensitive bacteria. Avibactam is a β-lactamase inhibitor currently being used in combination with β-lactams for the treatment of Gram-negative bacterial infections and is in clinical development. Avibactam belongs to the class of structural inhibitors that lack a β-lactam core structure but can covalently acylate their β-lactamase targets. We used the TEM-1 enzyme to characterize the inhibitory effect of avibactam by measuring the binding rate of the acylation reaction and the dissociation rate of the deacylation reaction. The dissociation rate of the deacylation reaction was 0.045 min⁻¹, which allowed us to study the deacylation pathway of TEM-1. We demonstrated using nuclear magnetic resonance (NMR) and mass spectrometry (MS) that deacylation is achieved through the regeneration of intact avibactam rather than hydrolysis. In addition to TEM-1, we also found that four other clinically significant β-lactamases can release intact avibactam after acylation. We found that avibactam is a covalent, slow, and reversible inhibitor, which is a unique inhibitory mechanism among β-lactamase inhibitors. [1]

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Background: In recent years, the incidence of carbapenem-resistant Enterobacteriaceae (CRE) infections has risen rapidly. Since CRE strains are usually resistant to most antimicrobial agents, the mortality rate of patients with this infection is often high. This poses a serious challenge to clinical infection management. This study aimed to investigate the in vitro and in vivo bactericidal activity of ceftazidime-avibactam alone or in combination with aztreonam against KPC or NDM carbapenemase-producing Klebsiella pneumoniae, and to explore new clinical treatment options for infections caused by its resistant strains. [3]
Methods: The minimum inhibitory concentration (MIC) was determined by the microbroth dilution method. Time-bactericidal curve tests were performed on 16 KPC-2 strains and 1 OXA-232 carbapenemase-producing Klebsiella pneumoniae strains at different concentrations of ceftazidime-avibactam. In this study, the checkerboard method was used to determine the in vitro synergistic bactericidal effect of ceftazidime-avibactam combined with aztreonam on 28 NDM strains and 2 NDM-KPC carbapenemase-Klebsiella pneumoniae strains. Based on the calculated rank, drugs with synergistic bactericidal effects were screened as the inhibitory concentration index (ICI). In vitro bactericidal tests of ceftazidime-avibactam combined with aztreonam were performed on 12 of the strains. In a mouse model, the efficacy of ceftazidime-avibactam against KPC carbapenemase-Klebsiella pneumoniae Y8 strain infection was studied. [3] Results: The time-bactericidal curve test showed that ceftazidime-avibactam at concentrations of 2MIC, 4MIC and 8MIC all showed significant bactericidal activity against drug-resistant strains. However, among the 28 NDM strains and 2 NDM-co-KPC carbapenemase-induced Klebsiella pneumoniae strains, only 7 were sensitive to ceftazidime-avibactam treatment, with MIC50 and MIC90 values of 64 mg/L and 256 mg/L, respectively. Antimicrobial susceptibility testing of ceftazidime-avibactam combined with aztreonam showed synergistic effects in 90% (27/30) of the strains, additive effects in 3.3% (1/30) of the strains, and no significant effect in 6.6% (2/30) of the strains. No antagonistic effects were observed. Subsequent bactericidal assays also confirmed these results. The efficacy of ceftazidime-avibactam in treating Klebsiella pneumoniae Y8 strain infection in mice showed a 70% mortality rate within 4 days in the infected group and all mice died within 13 days. Bacterial load testing showed no significant difference in bacterial counts in the blood of mice in the infected and treated groups. However, compared with the infection group, the colony-forming unit (CFU) counts in the spleen and liver of the treated mice were lower, indicating that ceftazidime-avibactam has a significant bactericidal effect on bacteria and a certain therapeutic effect. [3] Conclusion: This study shows that ceftazidime-avibactam treatment has a significant bactericidal effect on Klebsiella pneumoniae producing KPC-2 and OXA-232 carbapenemases. When used in combination with aztreonam, it has a stronger synergistic bactericidal effect on Klebsiella pneumoniae producing NDM carbapenemases. [3]

C7H12N3NAO7S

305.240851402283

305.029

2938989-90-1

Avibactam free acid;1192500-31-4;Avibactam sodium;1192491-61-4;Avibactam sodium dihydrate

118704750

White to off-white solid powder

0

2

7

3

19

462

2

C1C[C@H](N2C[C@@H]1N(C2=O)OS(=O)(=O)[O-])C(=O)N.O.[Na+]

QTECZIOYYRSGNA-CIFXRNLBSA-M

InChI=1S/C7H11N3O6S.Na.H2O/c8-6(11)5-2-1-4-3-9(5)7(12)10(4)16-17(13,14)15;;/h4-5H,1-3H2,(H2,8,11)(H,13,14,15);;1H2/q;+1;/p-1/t4-,5+;;/m1../s1

sodium;[(2S,5R)-2-carbamoyl-7-oxo-1,6-diazabicyclo[3.2.1]octan-6-yl] sulfate;hydrate

Avibactam sodium hydrate; Avibactam (sodium hydrate); 2938989-90-1; sodium;[(2S,5R)-2-carbamoyl-7-oxo-1,6-diazabicyclo[3.2.1]octan-6-yl] sulfate;hydrate; NXL-104 (hydrate);

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Note: Please store this product in a sealed and protected environment, avoid exposure to moisture.

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

H2O : ≥ 200 mg/mL (655.22 mM)

Solubility in Formulation 1: 25 mg/mL (81.90 mM) in PBS (add these co-solvents sequentially from left to right, and one by one), clear solution; with sonication.

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 (Please use freshly prepared in vivo formulations for optimal results.)