Kefzol (Cefazolin)

Cefazolin is a first‑generation cephalosporin antibiotic used to treat infections caused by susceptible bacteria.

• Skin and soft‑tissue infections: effective for treating mild to moderate infections of the skin and underlying tissues.
• Urinary tract infections: used to eradicate common uropathogens in uncomplicated and complicated UTIs.
• Respiratory tract infections: indicated for pneumonia and bronchitis caused by susceptible organisms.
• Bone and joint infections: employed in osteomyelitis and septic arthritis management.
• Surgical prophylaxis: administered pre‑operatively to prevent postoperative bacterial contamination.

• Cefazolin exerts its antibacterial effect by binding to penicillin‑binding proteins on the bacterial cell wall, inhibiting the final transpeptidation step of peptidoglycan synthesis. This disruption weakens the cell wall, leading to osmotic instability and bacterial lysis, particularly against Gram‑positive cocci and some Gram‑negative organisms.

Cefazolin may be associated with a range of adverse reactions, which are categorized by frequency and severity.

Common Side Effects

• Injection site pain: discomfort or erythema at the site of administration.
• Rash: mild skin eruptions that may appear during therapy.
• Nausea: feeling of unease or upset stomach.
• Vomiting: expulsion of stomach contents.
• Diarrhea: loose or watery stools.
• Transient elevation of liver enzymes: mild, reversible increase in hepatic markers.

Serious or Rare Side Effects

• Anaphylaxis: severe, potentially life‑threatening allergic reaction.
• Stevens‑Johnson syndrome: rare severe skin and mucous membrane disorder.
• Clostridioides difficile‑associated diarrhea: severe colitis following antibiotic use.
• Hemolytic anemia: destruction of red blood cells.
• Thrombocytopenia: significant reduction in platelet count.
• Acute interstitial nephritis: inflammation of kidney interstitium.

When using Cefazolin, clinicians should consider several precautionary measures to ensure patient safety.

• Renal impairment: monitor kidney function and adjust dosage as needed.
• Hypersensitivity: avoid in patients with known cephalosporin or penicillin allergy.
• Pregnancy: use only if the potential benefit justifies the potential risk to the fetus.
• Concomitant nephrotoxic drugs: exercise caution when combined with other agents that may affect renal function.
• Prolonged therapy: assess for emergence of secondary infections such as C. difficile.
• Store at 2‑8°C: keep refrigerated, protect from light, do not freeze or shake the product.

Cefazolin can interact with other medicines, influencing efficacy or toxicity.

Major Interactions (Avoid)

• Aminoglycosides: increased risk of nephrotoxicity when co‑administered.
• Loop diuretics: heightened potential for ototoxicity.
• Warfarin: possible enhancement of anticoagulant effect, requiring INR monitoring.

Moderate Interactions (Monitor Closely)

• Probenecid: may raise cefazolin plasma concentrations.
• Oral contraceptives: potential reduction in hormonal efficacy.
• Methotrexate: risk of increased toxicity due to reduced renal clearance.
• NSAIDs: may affect renal function when used together.
• Calcium‑containing solutions: can reduce cefazolin stability if mixed.