Cefazolin: Full Review
Cefazolin is a first-generation cephalosporin antibiotic commonly used for its broad-spectrum activity against Gram-positive and some Gram-negative bacteria. It is often administered intravenously or intramuscularly due to its poor oral absorption.
1. Mechanism of Action
Cefazolin works by inhibiting bacterial cell wall synthesis. It binds to penicillin-binding proteins (PBPs) on the bacterial cell wall, which prevents the formation of cross-links between peptidoglycan layers. This disruption weakens the cell wall, leading to bacterial lysis and death. Cefazolin is bactericidal, meaning it kills bacteria rather than just inhibiting their growth.
2. Uses
Cefazolin is used to treat a variety of infections, including:
- Surgical Prophylaxis: Commonly used to prevent infections during surgery, especially in clean and contaminated procedures.
- Skin and Soft Tissue Infections: Such as cellulitis, impetigo, and wound infections.
- Upper Respiratory Tract Infections: Including pharyngitis and tonsillitis.
- Urinary Tract Infections (UTIs): Including cystitis and pyelonephritis.
- Bone and Joint Infections: Such as osteomyelitis.
- Endocarditis: For specific bacterial causes, often as part of combination therapy.
3. Dosage and Administration
Cefazolin is administered intravenously (IV) or intramuscularly (IM). The dosage depends on the type and severity of the infection:
- Adults: 1 to 2 grams IV/IM every 8 hours, with doses up to 12 grams per day for severe infections.
- Children: 25 to 50 mg/kg IV/IM every 8 hours, with adjustments based on the severity of the infection.
4. Contraindications
Cefazolin is contraindicated in:
- Patients with hypersensitivity to cephalosporins or penicillins (due to potential cross-reactivity).
- Patients with a history of severe allergic reactions to beta-lactam antibiotics.
- Severe renal impairment: Dose adjustments are necessary for patients with significant kidney dysfunction.
5. Side Effects
Common side effects of cefazolin include:
- Gastrointestinal issues: Nausea, vomiting, diarrhea, and abdominal pain.
- Allergic reactions: Rash, itching, and anaphylaxis in rare cases.
- Hematologic effects: Rarely, leukopenia, thrombocytopenia, or eosinophilia.
- Renal effects: Rare instances of interstitial nephritis or acute kidney injury.
- Injection site reactions: Pain, redness, or swelling at the injection site.
6. Drug Interactions
- Anticoagulants: Cefazolin can enhance the effects of anticoagulants like warfarin, increasing the risk of bleeding.
- Probenecid: May increase cefazolin levels by inhibiting its renal excretion.
- Other nephrotoxic drugs: Caution is advised when used with drugs that affect kidney function.
7. Special Precautions
- Renal Function: Dose adjustments are needed for patients with renal impairment to avoid toxicity.
- Allergies: Patients with a history of penicillin allergy should be monitored for potential cross-reactivity.
- Superinfections: Prolonged use can lead to the overgrowth of resistant organisms or fungal infections.
8. Resistance
Resistance to cefazolin can develop through several mechanisms:
- Beta-lactamase production: Enzymes that break down cefazolin, reducing its effectiveness.
- Altered PBPs: Bacteria may alter their PBPs to reduce cefazolin binding.
- Efflux pumps: Some bacteria may pump cefazolin out of the cell before it can act.
9. Storage and Stability
Cefazolin should be stored at room temperature, away from moisture and heat. The reconstituted solution should be used within 24 hours if stored at room temperature or within 48 hours if refrigerated.
10. Summary
Cefazolin is a first-generation cephalosporin effective against a range of bacterial infections, especially those caused by Gram-positive organisms. It is commonly used for surgical prophylaxis and in treating skin, respiratory, urinary tract, and bone infections. While generally well-tolerated, cefazolin can cause gastrointestinal disturbances, allergic reactions, and other side effects. Careful consideration of patient allergies, renal function, and potential drug interactions is essential for safe and effective use.
