What is the recommended dose of Ancef (cefazolin) for a 9-year-old male weighing 63 pounds with a facial laceration?

Cefazolin Dosing for Facial Laceration in a 9-Year-Old, 63-Pound Male

For this 9-year-old male weighing 63 pounds (28.6 kg) with a facial laceration, administer cefazolin 33 mg/kg/dose IV every 8 hours, which equals approximately 950 mg per dose (can round to 1 gram for practical administration). 1

Weight-Based Calculation

• Patient weight: 63 pounds = 28.6 kg
• Recommended pediatric dosing: 33 mg/kg/dose every 8 hours for skin and soft tissue infections 1
• Calculated dose: 28.6 kg × 33 mg/kg = 943 mg per dose (round to 1 gram for ease of administration)
• Frequency: Every 8 hours 1

Rationale for This Dosing

• Cefazolin is the preferred first-generation cephalosporin for skin and soft tissue infections caused by methicillin-susceptible Staphylococcus aureus (MSSA), which is the most common pathogen in traumatic skin injuries like facial lacerations 1
• The FDA-approved pediatric dosing range is 25-50 mg/kg/day divided into 3-4 doses for mild to moderate infections, with up to 100 mg/kg/day for severe infections 2
• The 33 mg/kg/dose every 8 hours (approximately 100 mg/kg/day total) falls within the higher end of the recommended range, appropriate for ensuring adequate tissue penetration in facial wounds 1

Duration of Therapy

• For uncomplicated facial lacerations, a short course is typically sufficient (generally 5-7 days or until clinical improvement is evident) 1
• Do not extend therapy unnecessarily beyond clinical indication to avoid antimicrobial resistance 1

Administration Considerations

• For IV bolus administration: Reconstitute and further dilute with approximately 5 mL Sterile Water for Injection, then inject slowly over 3-5 minutes 2
• For intermittent infusion: Dilute in 50-100 mL of compatible solution (0.9% sodium chloride or 5% dextrose) 2
• Administer 30-60 minutes before any surgical repair if wound closure is planned 3

Important Clinical Caveats

• Penicillin allergy is NOT a contraindication to cefazolin in most cases, as cross-reactivity between penicillin and cefazolin is extremely low due to different R1 side chains 4
• Only avoid cefazolin if the patient has a history of severe delayed hypersensitivity reactions (Stevens-Johnson syndrome, hepatitis, nephritis, serum sickness, or hemolytic anemia) to penicillin 4
• Assess renal function: If creatinine clearance is reduced, dosing adjustments may be needed, though this is uncommon in healthy 9-year-olds 2
• For facial wounds specifically, ensure adequate coverage against S. aureus and Streptococcus pyogenes, both of which are well-covered by cefazolin 3

Alternative Considerations

• If MRSA is suspected based on local epidemiology or patient risk factors (prior MRSA infection, recent hospitalization), consider adding vancomycin or switching to clindamycin 3
• For contaminated wounds with soil or animal exposure, broader coverage may be needed, but for simple facial lacerations, cefazolin monotherapy is appropriate 3