Cephalexin Dosing for a 70-Pound Child
The recommended dose of cephalexin for a 70-pound (approximately 32 kg) child is 25-50 mg/kg/day divided into 3-4 doses, which equals approximately 800-1600 mg total daily dose, typically given as 200-400 mg per dose four times daily or 267-533 mg per dose three times daily. 1
Standard Dosing Recommendations
- The FDA-approved dosage for cephalexin in pediatric patients is 25-50 mg/kg/day divided into equal doses administered every 6 hours (four times daily) 1
- For a 70-pound (32 kg) child, this translates to:
- 800-1600 mg total daily dose
- 200-400 mg per dose when given four times daily 1
- For streptococcal pharyngitis and skin/skin structure infections, the total daily dose may be divided and administered every 12 hours (twice daily) 1
- For otitis media, a higher dosage of 75-100 mg/kg/day in 4 divided doses is recommended 1
Alternative Dosing Schedules
- Three-times-daily dosing at 45 mg/kg/dose (maximum 1.5 g per dose) has been shown to be effective and well-tolerated in children with bone and joint infections 2
- For a 32 kg child, this would be approximately 1440 mg/day (480 mg three times daily)
- Recent pharmacokinetic studies support less frequent dosing regimens to improve treatment adherence:
Specific Clinical Scenarios
- For streptococcal pharyngitis, treatment should continue for at least 10 days 1
- For severe infections, the standard dosage may be doubled 1
- For methicillin-susceptible Staphylococcus aureus (MSSA) infections, cephalexin is an appropriate choice 4
Administration Considerations
- Cephalexin suspension is available in two concentrations: 125 mg/5 mL and 250 mg/5 mL 1
- For a 40 kg (88 lb) child (closest to our 70 lb/32 kg child in the FDA table):
Pharmacokinetic Considerations
- Cephalexin is rapidly absorbed in the upper intestine and achieves good tissue distribution 5
- Children may require higher doses per kilogram than adults due to their greater body water turnover 5
- Cephalexin is primarily eliminated by the kidneys, with 70-100% of the dose found in urine 6-8 hours after administration 5
Recent Evidence on Dosing Frequency
- A 2024 study found that cephalexin 25 mg/kg/dose (maximum 750 mg/dose) administered three times daily achieved adequate pharmacodynamic targets for MSSA infections 6
- This supports the trend toward less frequent dosing while maintaining efficacy
Remember that cephalexin should be administered for the full prescribed course to ensure complete eradication of the infection and prevent the development of resistant bacteria.