Cefazolin Dosing for a 70kg 14-Year-Old
For a 70kg 14-year-old, the recommended dose of cefazolin is 100 mg/kg/day divided every 8 hours, which equals approximately 2.3 grams every 8 hours. 1
Dosing Calculation
The FDA-approved cefazolin dosing for pediatric patients provides clear guidance:
- For pediatric patients, the total daily dosage is 25-50 mg/kg divided into 3-4 equal doses for mild to moderate infections 1
- For severe infections, the total daily dosage may be increased to 100 mg/kg 1
- For a 14-year-old weighing 70kg, this patient should be dosed according to pediatric guidelines since they are still considered a pediatric patient
Specific Dosing Calculation:
- Severe infection dose: 100 mg/kg/day
- For 70kg patient: 100 mg/kg × 70kg = 7,000 mg/day (7 grams/day)
- Divided into 3 doses (every 8 hours): 2,333 mg per dose (rounded to 2.3 grams)
Special Considerations
Age-Based Considerations
- At 14 years old, this patient is in the pediatric category but approaching adult dosing parameters
- The Infectious Diseases Society of America (IDSA) guidelines specifically recommend cefazolin at 75-100 mg/kg/day divided every 8 hours for children over 1 month of age 2
Weight-Based Considerations
- At 70kg, this patient's weight is in the adult range, but age-based dosing should still be followed
- For endocarditis prophylaxis, the American Heart Association recommends cefazolin 100 mg/kg/day divided every 8 hours for children 2
Infection Type Considerations
- For surgical prophylaxis, a single dose of 100 mg/kg (maximum 2g) would be appropriate 2
- For treatment of established infections, the full therapeutic dose as calculated above should be used
Safety Considerations
Maximum Daily Dose
- The maximum daily dose should not exceed 12 grams per day, even in severe infections 1
- The calculated dose of 7 grams/day is within this safety limit
Renal Function Monitoring
- Renal function should be monitored as cefazolin is primarily eliminated through the kidneys 3
- Dose adjustment is necessary if renal dysfunction is present to prevent neurotoxicity 4
Administration Considerations
- Intravenous administration should be given slowly to prevent adverse reactions
- For prolonged therapy (>48 hours), monitor for superinfection and consider probiotic supplementation
Conclusion
For a 70kg 14-year-old requiring cefazolin therapy, administer 2.3 grams every 8 hours intravenously for severe infections. For mild to moderate infections, consider using the lower range of 25-50 mg/kg/day (approximately 1.2-2.3 grams every 8 hours). Always adjust dosing based on clinical response and renal function.