Avibactam

Drug Name

Avibactam is not a β-lactam itself but a β-lactamase inhibitor administered in combination with ceftazidime in a drug known as Avycaz. It inactivates some β-lactamases (Ambler class A β-lactamases, Ambler class C, and some Ambler class D β-lactamases) by a covalent and reversible mechanism and protects ceftazidime from degradation by β-lactamases. 

Table 1. Basic profile of Avibactam.

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Inhibitor Chemistry

Avibactam is a member of the class of azabicycloalkanes in which the amino hydrogen at position 6 is replaced by a sulfooxy group (Figure 2).

Figure 2. 2D structure of avibactam showing the functional moieties responsible for its anti-β-lactamase activity. Structure created using ChemDraw.

Drug Information

Table 2. Chemical and physical properties (DrugBank)

Drug Target

Avibactam targets β-lactamase enzymes. These bacterial enzymes hydrolyze the amide bond of the β-lactam ring in β-lactam antibiotics, rendering them unable to inhibit their target enzyme. Learn more about β-lactamases.

The inhibitor avibactam is administered with ceftazidime to inhibit β-lactamases from degrading the antibiotic, as an effective mechanism against resistance to ceftazidime by bacteria. Avibactam mimics the interactions between ceftazidime and β-lactamases, thereby preventing the β-lactamases from degrading ceftazidime.

Avibactam interacts with Ambler classes A and C and some Ambler class D β-lactamases via covalent binding. The target of avibactam, CTX-M-15 (class A β-lactamase) will be discussed here.

Drug-Target Complex

One target of avibactam, CTX-M-15, is an Ambler class A β-lactamase. CTX-M family of β-lactamases are clinically important and were named for their enhanced activity against the third-generation cephalosporin cefotaxime (Jia et al., 2017). CTX-M genes have been found on many kinds of mobile genetic elements and can be transmitted to other bacteria. Consequently, these genes have become the most prevalent extended-spectrum β-lactamase and have greater potential to spread beyond hospital environments.

CTX-M-15 cleaves the amide bond of a β-lactam drug in 2 steps: acylation and deacylation. The oxygen of the Ser70 residue in CTX-M-15 attacks the carbonyl atom, and causes acylation of the β-lactam ring to form an acyl intermediate. This initiates a cascade of proton transfers, ultimately resulting in the cleavage of the amide bond. Deacylation regenerates the catalytic serine residue, releasing the hydrolyzed antibiotic.

Avibactam forms a covalent adduct with the catalytic Ser70, mimicking the transition state of the acylation and deacylation pathway. This blocks the active site of CTX-M-15 and prevents it from cleaving β-lactam antibiotics like ceftazidime. In addition to the covalent binding at Ser70, various other amino acids in the neighborhood form hydrogen bonds with the inhibitor (Figure 3), either directly (e.g., Asn104, Asn132, Ser130, Cys69, Lys73, Ser237, and Thr235) or mediated by water molecules (e.g., Asn170, Glu166, and Thr216).

Figure 3. Ribbon representation of CTX-M-15 bound to avibactam (shown in magenta). The inset shows the covalent linkage between avibactam and Ser70 and non-covalent interactions with various other amino acids. (PDB ID: 4hbu; Lahiri et al., 2013).

Pharmacologic Properties and Safety

Table 3. Pharmacokinetics: ADMET of avibactam.

Drug Interactions and Side Effects

Table 4. Drug interactions and side effects of avibactam.

Regulatory Approvals/Commercial

Avibactam is used with antibiotics ceftazidime and aztreonam as an adjuvant to prevent the drug from being degraded by β-lactamases and increase its antibacterial properties. This combination (Avycaz) was approved by the FDA in February 2015.

Learn more about ceftazidime and aztreonam.

Links

Table 5: Links to learn more about Avibactam

References

Avibactam and cefTAZidime - Drugs.com https://www.drugs.com/mtm/avibactam-and-ceftazidime.html

Avibactam - DrugBank https://go.drugbank.com/drugs/DB09060

Avibactam - PubChem - https://pubchem.ncbi.nlm.nih.gov/compound/9835049

AVYCAZ - FDA - https://www.accessdata.fda.gov/drugsatfda_docs/label/2018/206494s004lbl.pdf

Chauzy, A., Buyck, J., de Jonge, B. L., Marchand, S., Grégoire, N., Couet, W. (2019). Pharmacodynamic modelling of β-lactam/β-lactamase inhibitor checkerboard data: illustration with aztreonam–avibactam. Clinical Microbiology and Infection, 25(4), 515-e1. https://doi.org/10.1016/j.cmi.2018.11.025

Hecker, S. J., Reddy, K. R., Totrov, M., Hirst, G. C., Lomovskaya, O., Griffith, D. C., King, P., Tsivkovski, R., Sun, D., Sabet, M., Tarazi, Z., Clifton, M. C., Atkins, K., Raymond, A., Potts, K. T., Abendroth, J., Boyer, S. H., Loutit, J. S., Morgan, E. E., Durso, S., Dudley, M.N. (2015) Discovery of a Cyclic Boronic Acid β-Lactamase Inhibitor (RPX7009) with Utility vs Class A Serine Carbapenemases. J Med Chem. 58, 3682-92. https://doi.org/10.1021/acs.jmedchem.5b00127

Jia, B., Raphenya, A. R., Alcock, B., Waglechner, N., Guo, P., Tsang, K. K., Lago, B. A., Dave, B. M., Pereira, S., Sharma, A. N., Doshi, S., Courtot, M., Lo, R., Williams, L. E., Frye, J. G., Elsayegh, T., Sardar, D. Westman, E. L., Pawlowski, A. C., Johnson, T. A., Brinkman, F. S., Wright, G. D., McArthur, A. G. (2017) CARD 2017: expansion and model-centric curation of the Comprehensive Antibiotic Resistance Database. Nucleic Acids Research 45, D566-573. https://doi.org/10.1093/nar/gkw1004

Lahiri, S. D., Mangani, S., Durand-Reville, T., Benvenuti, M., De Luca, F., Sanyal, G., Docquier, J. D. (2013). Structural insight into potent broad-spectrum inhibition with reversible recyclization mechanism: avibactam in complex with CTX-M-15 and Pseudomonas aeruginosa AmpC β-lactamases. Antimicrobial agents and chemotherapy, 57(6), 2496-2505. https://doi.org/10.1128/AAC.02247-12

LiverTox: Pharmacokinetic Enhancers - https://www.ncbi.nlm.nih.gov/books/NBK547913/

April 2025, Helen Gao, Gauri Patel, Shuchismita Dutta; Reviewed by Dr. Gregg Crichlow
https://doi.org/10.2210/rcsb_pdb/GH/AMR/drugs/OR/inh-blmase/avibactam