What is Cefazolin?
Cefazolin is a first-generation
cephalosporin antibiotic used to treat a wide variety of bacterial infections. It works by stopping the growth of bacteria and is often used for treating infections caused by
Gram-positive bacteria. Cefazolin is typically administered through an injection, which allows it to reach effective concentrations in the bloodstream quickly.
Mechanism of Action
Cefazolin works by inhibiting the synthesis of the bacterial
cell wall, leading to cell death. It binds to specific penicillin-binding proteins (PBPs) inside the bacterial cell wall, inhibiting the final transpeptidation step of peptidoglycan synthesis. This results in the weakening of the cell wall and eventual
lysis of the bacterial cell.
Dosage and Administration
The dosage of cefazolin varies depending on the type and severity of the infection, as well as the patient's age, weight, and renal function. It is typically administered intravenously or intramuscularly. For adults, the usual dose ranges from 1 to 2 grams every 8 hours. In surgical prophylaxis, a single dose of 1 to 2 grams is typically given 30 to 60 minutes prior to surgery.Side Effects and Contraindications
Common side effects of cefazolin include rash, diarrhea, nausea, vomiting, and
phlebitis at the injection site. Serious adverse effects, although rare, can include
anaphylaxis and
Clostridium difficile-associated diarrhea. Cefazolin is contraindicated in patients with a known hypersensitivity to cephalosporins or penicillins, as cross-reactivity can occur.
Drug Interactions
Cefazolin may interact with other medications, potentially altering its effectiveness or increasing the risk of adverse effects. For instance, concurrent use with
probenecid can increase cefazolin levels in the blood, enhancing its effects. It is also important to monitor patients on
anticoagulants, as cefazolin can enhance the anticoagulant effect, increasing the risk of bleeding.
Pharmacokinetics
Cefazolin is well-distributed throughout the body, including the lungs, liver, kidneys, bone, and heart. However, it does not penetrate the central nervous system effectively, making it unsuitable for treating
meningitis. The drug is primarily excreted unchanged in the urine, and its half-life is approximately 1.8 hours in patients with normal renal function. Adjustments in dosing may be necessary for patients with renal impairment to prevent accumulation and toxicity.
Resistance Patterns
Resistance to cefazolin can occur through various mechanisms, such as the production of
beta-lactamases that inactivate the drug. It is important to consider local resistance patterns and susceptibility testing when selecting cefazolin as a treatment option. The overuse and misuse of antibiotics like cefazolin can contribute to the development of resistant bacterial strains, making antimicrobial stewardship crucial in healthcare settings.
Conclusion
Cefazolin remains a valuable antibiotic for the treatment and prevention of a variety of bacterial infections, especially those caused by Gram-positive organisms. Its safety profile, efficacy, and ease of administration make it a go-to choice in both clinical and surgical settings. However, careful consideration of patient-specific factors, potential drug interactions, and local resistance patterns is essential to optimize its use and maintain its effectiveness.
