Cefazolin Dosing Based on Weight
The recommended cefazolin dosage is 100 mg/kg/day divided every 8 hours for pediatric patients, with a maximum of 12 g daily, and for adults, standard dosing is typically 1-2 g every 8 hours depending on infection severity and weight. 1, 2
Pediatric Dosing
Standard Therapeutic Dosing
Weight-Based Considerations for Pediatrics
- For patients <25 kg: Dose based strictly on weight (100 mg/kg/day)
- For patients 25-50 kg: 1 g every 8 hours 3
- For patients ≥50 kg: 2 g every 8 hours 3
Surgical Prophylaxis in Children
Adult Dosing
Standard Therapeutic Dosing
- Mild to moderate infections: 1 g every 8 hours 4
- Severe infections: 1-2 g every 6-8 hours 4
- Maximum daily dose: 12 g daily 1
Weight-Based Considerations for Adults
- For patients ≤120 kg: Standard dosing (up to 6 g/day) 5
- For patients >120 kg: Consider higher dosing (up to 9 g/day) for severe infections 5
Surgical Prophylaxis in Adults
- Standard weight: 1-2 g IV 30-60 minutes before incision 4, 6
- Morbid obesity (BMI 40-50): 2 g provides adequate coverage for procedures lasting up to 5 hours 6
- Super-morbid obesity (BMI >50): 3 g may provide slightly longer coverage (6.8 hours vs 5.8 hours) 6
Special Considerations
Renal Impairment Adjustments
- CrCl 55 mL/min or greater: Full dose 4
- CrCl 35-54 mL/min: Full dose but extend interval to every 8 hours 4
- CrCl 11-34 mL/min: Half the usual dose every 12 hours 4
- CrCl 10 mL/min or less: Half the usual dose every 18-24 hours 4
Duration of Protection
- A single 2 g dose provides approximately 5-6 hours of surgical site protection 6, 7
- Intraoperative redosing is only necessary for procedures lasting longer than 5-6 hours 6, 8
Clinical Pearls
- Cefazolin is a hydrophilic antibiotic that does not penetrate adipose tissue well regardless of dose 8
- Higher doses in obesity do not significantly increase tissue penetration but do increase serum concentrations 8
- For endocarditis treatment, cefazolin is dosed at 100 mg/kg/day divided every 8 hours for children, with a maximum of 12 g daily 1
- Continuous infusion may achieve better target attainment than intermittent dosing for major surgeries 7
Remember that while weight-based dosing is important, pharmacokinetic factors such as distribution volume and clearance also significantly impact appropriate dosing, especially in patients with obesity or renal impairment.