What is the dosage and usage of cefazolin for treating bacterial infections?

Cefazolin Dosage and Usage for Bacterial Infections

For treating bacterial infections, cefazolin should be dosed at 500 mg to 1 gram every 6 to 8 hours for moderate to severe infections, with adjustments based on infection type, severity, and renal function. 1

Adult Dosing Guidelines

Standard Dosing by Infection Type

• Moderate to severe infections: 500 mg to 1 gram IV/IM every 6 to 8 hours 1
• Mild infections (susceptible gram-positive cocci): 250 mg to 500 mg IV/IM every 8 hours 1
• Acute, uncomplicated urinary tract infections: 1 gram IV/IM every 12 hours 1
• Pneumococcal pneumonia: 500 mg IV/IM every 12 hours 1
• Severe, life-threatening infections (endocarditis, septicemia): 1 gram to 1.5 grams IV/IM every 6 hours 1

Perioperative Prophylaxis

• Pre-surgery: 1 gram IV/IM 30-60 minutes before incision 1
• During lengthy procedures (>2 hours): 500 mg to 1 gram IV/IM during surgery 1
• Post-surgery: 500 mg to 1 gram IV/IM every 6 to 8 hours for 24 hours 1
• For high-risk surgeries (e.g., joint prosthesis, open-heart surgery): 2 grams IV slow, with 1 gram if duration >4 hours, limited to operative period (24 hours maximum) 2
• For spine surgery with implantation: 2 grams IV slow, with additional 1 gram if duration >4 hours 2

Dosage Adjustments for Special Populations

Renal Impairment

• CrCl ≥55 mL/min or SCr ≤1.5 mg%: Standard dosing 1
• CrCl 35-54 mL/min or SCr 1.6-3 mg%: Standard dose at minimum 8-hour intervals 1
• CrCl 11-34 mL/min or SCr 3.1-4.5 mg%: 1/2 standard dose every 12 hours 1
• CrCl ≤10 mL/min or SCr ≥4.6 mg%: 1/2 standard dose every 18-24 hours 1

Pediatric Dosing

• Mild to moderate infections: 25-50 mg/kg/day divided into 3-4 doses 1
• Severe infections: Up to 100 mg/kg/day 1
• Not recommended for premature infants and neonates 1

Pediatric Renal Impairment

• CrCl 70-40 mL/min: 60% of normal daily dose divided every 12 hours 1
• CrCl 40-20 mL/min: 25% of normal daily dose divided every 12 hours 1
• CrCl 20-5 mL/min: 10% of normal daily dose every 24 hours 1

Administration Methods

Intramuscular Administration

• Reconstitute with Sterile Water for Injection 1
• Inject into large muscle mass 1

Intravenous Administration

• Direct (bolus) injection: Dilute with approximately 5 mL Sterile Water for Injection and inject slowly over 3-5 minutes 1
• Intermittent/continuous infusion: Dilute in 50-100 mL of compatible solution 1

Alternative Administration Routes

• Subcutaneous administration: While not FDA-approved, recent research suggests subcutaneous cefazolin at 3g twice daily may be an alternative to standard IV dosing of 2g three times daily in certain situations 3

Clinical Considerations

Target Organisms

• Effective against staphylococci, pneumococci, Escherichia coli, Klebsiella sp., and Proteus mirabilis 4
• For skin and soft tissue infections, provides coverage against Staphylococcus aureus and beta-hemolytic streptococci 5

Treatment Duration

• Uncomplicated skin infections: 5-7 days 6
• Respiratory tract infections: 7-10 days 6
• Bacteremia (uncomplicated): 10-14 days 6
• Endocarditis/osteomyelitis: 4-6 weeks 6

Important Considerations and Pitfalls

• Always obtain cultures before starting antibiotics when possible to guide targeted therapy 6
• For trauma cases: In closed fractures requiring intrafocal osteosynthesis, use 2g slow IV with 1g if duration >4 hours, limited to operative period (24 hours maximum) 2
• For open fractures: Cefazolin achieves sustained high interstitial concentrations above the MIC for Staphylococcus aureus, even in traumatized tissue 7
• Timing is critical for surgical prophylaxis: Administer 30-60 minutes before incision to ensure adequate tissue levels at time of initial surgical incision 1
• Alternative regimens: For patients with penicillin allergy, consider clindamycin (900 mg IV slow) or vancomycin (30 mg/kg over 120 minutes) 2

Cefazolin remains a highly effective first-generation cephalosporin for a wide range of bacterial infections when dosed appropriately based on infection type, severity, and patient factors.