What is the recommended dosage of Keflex (cephalexin) for an 8-year-old child?

Cephalexin (Keflex) Dosing for an 8-Year-Old Child

The recommended dosage of cephalexin (Keflex) for an 8-year-old child is 25-50 mg/kg/day divided into 4 doses (6.25-12.5 mg/kg every 6 hours) or 2-3 doses for certain infections. 1

Standard Dosing Recommendations

• The FDA-approved dosage for pediatric patients is 25-50 mg/kg/day divided into 4 doses 1
• For an 8-year-old child (approximately 25-30 kg), this translates to:
  • 625-1500 mg total daily dose
  • 156-375 mg per dose when given 4 times daily 1

Dosing by Infection Type

• For skin and skin structure infections:

  • The total daily dose may be divided and administered every 12 hours (twice daily) 1
  • 312-750 mg per dose when given twice daily 2

• For streptococcal pharyngitis:

  • The total daily dose may be divided and administered every 12 hours 1
  • Treatment should continue for at least 10 days for β-hemolytic streptococcal infections 1

• For otitis media:

  • A higher dosage of 75-100 mg/kg/day in 4 divided doses is required 1
  • This would be approximately 468-750 mg per dose for an 8-year-old child 1

Alternative Dosing Schedules

Recent research suggests that less frequent dosing may be effective while improving adherence:

• Three times daily dosing:

  • 45 mg/kg/dose (maximum 1.5 g) three times daily has shown efficacy in bone and joint infections 3
  • This regimen achieves the same pharmacodynamic target as four times daily dosing 3

• Twice daily dosing:

  • For methicillin-susceptible Staphylococcus aureus (MSSA) infections, doses of 22-45 mg/kg twice daily may be effective for organisms with MICs of 1-2 mg/L 4
  • Higher doses (80 mg/kg twice daily) may be needed for organisms with MIC of 4 mg/L 4

Administration Considerations

• Cephalexin suspension should be prepared at the time of dispensing 1
• After mixing, store the suspension in the refrigerator 1
• The suspension may be kept for 14 days without significant loss of potency 1
• Cephalexin is not absorbed from the stomach but is totally and rapidly absorbed in the upper intestine 5

Important Clinical Considerations

• Children may need higher doses per kilogram than adults due to their greater body water turnover 5
• Cephalexin is rapidly cleared from the body by the kidneys, with 70-100% of the dose found in the urine 6-8 hours after each dose 5
• Dose adjustment is necessary for patients with creatinine clearance less than 30 ml/min 5
• Common side effects include gastrointestinal symptoms and, rarely, mild neutropenia 3

For an 8-year-old child with normal renal function, the standard dosing of 25-50 mg/kg/day divided into 4 doses is appropriate for most infections, with consideration for twice or three times daily dosing to improve adherence in certain situations.