tazobactam
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| tazobactam | |
|---|---|
| IUPAC name | (2S,3S,5R)-3-Methyl-7-oxo-3-(1H-1,2,3-triazol-1-ylmethyl)-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid 4,4-dioxide |
| CAS number | 89786-04-9 |
| PubChem | 123630 |
| DrugBank | DB01606 |
| ChemSpiderID | 110217 |
| Molecular weight | 300.3 g/mol |
tazobactam is a potent beta-lactamase inhibitor used in clinical medicine to extend the antibacterial spectrum of certain penicillin antibiotics. It is co-formulated exclusively with the ureidopenicillin piperacillin in the widely used combination drug piperacillin/tazobactam, marketed under the brand name Zosyn. By irreversibly inhibiting a broad range of bacterial enzymes that confer antibiotic resistance, tazobactam restores the efficacy of its partner antibiotic against many resistant pathogens, making it a critical agent in hospital-acquired infection management.
Chemical structure and properties
Tazobactam is a synthetic penicillanic acid sulfone derivative, sharing a core beta-lactam ring structure with penicillin antibiotics but lacking significant intrinsic antibacterial activity. Its chemical design incorporates a triazole ring, which contributes to its stability and binding affinity. The compound exists as a white to pale yellow crystalline powder that is freely soluble in water and methanol, properties that facilitate its formulation for intravenous administration. The presence of the sulfone group adjacent to the beta-lactam ring is a key structural feature essential for its mechanism as a mechanism-based inactivator of beta-lactamase.
Mechanism of action
The primary mechanism of tazobactam involves the irreversible inhibition of serine beta-lactamase enzymes, including many from the Ambler class A and some from Ambler class C. It acts as a suicide inhibitor, where its own beta-lactam ring is cleaved by the active-site serine residue of the bacterial enzyme, forming a stable acyl-enzyme complex that permanently inactivates the beta-lactamase. This process protects co-administered piperacillin from enzymatic hydrolysis, allowing it to reach its target, the penicillin-binding proteins in the bacterial cell wall. Unlike clavulanic acid, tazobactam exhibits greater stability against inhibition by certain plasmid-mediated beta-lactamases such as TEM-1.
Clinical use and spectrum of activity
Tazobactam is used clinically only in combination with piperacillin for the treatment of moderate-to-severe infections caused by susceptible organisms. The spectrum of piperacillin/tazobactam includes many Gram-positive, Gram-negative, and anaerobic organisms. It is a first-line agent for complicated intra-abdominal infection, nosocomial pneumonia, skin and soft tissue infection, and sepsis of unknown origin, particularly in settings like the intensive care unit. The combination is notably active against Pseudomonas aeruginosa, Enterobacteriaceae producing extended-spectrum beta-lactamases, and Bacteroides fragilis.
Pharmacokinetics and pharmacodynamics
Following intravenous administration, tazobactam exhibits pharmacokinetics similar to its partner piperacillin, with a volume of distribution approximating extracellular fluid and low protein binding. It is primarily eliminated unchanged by renal excretion via glomerular filtration and tubular secretion, necessitating dosage adjustment in patients with renal impairment. The pharmacodynamic index correlating with efficacy for beta-lactamase inhibitors like tazobactam is the time that the free drug concentration exceeds a threshold, which guides dosing regimens to maintain inhibitory concentrations throughout the dosing interval.
Adverse effects and safety
The safety profile of tazobactam is largely defined by the combination product piperacillin/tazobactam. Common adverse effects are related to the penicillin class and include gastrointestinal disturbances such as diarrhea and nausea, as well as skin rash and injection site reaction. Serious but rare risks include Clostridioides difficile infection, acute interstitial nephritis, and hematologic abnormalities like leukopenia. As with all beta-lactam antibiotics, there is a risk of hypersensitivity reaction, including anaphylaxis, particularly in patients with a history of penicillin allergy.
History and development
Tazobactam was developed in the 1980s by the Japanese pharmaceutical company Taiho Pharmaceutical as part of a global research effort to overcome escalating beta-lactamase-mediated resistance. It was designed as a more stable and potent successor to earlier inhibitors like clavulanic acid and sulbactam. The combination with piperacillin was subsequently developed and co-marketed by Lederle Laboratories and was approved for medical use in the United States in 1993. Its introduction provided a crucial therapeutic option during a period of rising resistance to third-generation cephalosporins.
Resistance and combination therapy
While tazobactam inhibits a wide array of beta-lactamases, resistance can emerge through several mechanisms. These include the production of beta-lactamases that are poorly inhibited, such as some metallo-beta-lactamases like NDM-1 and certain Ambler class D enzymes like OXA-48, as well as alterations in porin channels that reduce drug entry or upregulation of efflux pump systems. The strategic use of piperacillin/tazobactam in combination therapy, sometimes with other agents like aminoglycosides, is a cornerstone of antimicrobial stewardship programs to delay resistance and treat multidrug-resistant organisms effectively.