What is the appropriate cephalexin dose for an 11‑year‑old child weighing 61.46 kg using a suspension of 250 mg per 5 mL?

Cephalexin Dosing for an 11-Year-Old Weighing 61.46 kg

For this 11-year-old child weighing 61.46 kg, the appropriate cephalexin dose using 250 mg/5 mL suspension is 1,500 mg per dose (30 mL of suspension), administered 3 to 4 times daily depending on the infection severity and type.

Dose Calculation

Standard Pediatric Dosing Range

• The usual recommended daily dosage for pediatric patients is 25 to 50 mg/kg/day in divided doses 1
• For this 61.46 kg child:
  • Minimum daily dose: 25 mg/kg × 61.46 kg = 1,536.5 mg/day
  • Maximum daily dose: 50 mg/kg × 61.46 kg = 3,073 mg/day

Practical Dosing with 250 mg/5 mL Suspension

For moderate infections (standard dosing):

• 375-500 mg (7.5-10 mL) every 6 hours (4 times daily)
• This provides 1,500-2,000 mg/day total 1

For more severe infections or less susceptible organisms:

• 500-750 mg (10-15 mL) every 6 hours (4 times daily)
• This provides 2,000-3,000 mg/day total 1

Alternative twice-daily dosing for specific infections:

• For streptococcal pharyngitis and uncomplicated skin/soft tissue infections, the total daily dose may be divided and administered every 12 hours 1
• This would be 750-1,000 mg (15-20 mL) twice daily

Infection-Specific Recommendations

For Staphylococcus aureus (Methicillin-Susceptible) Infections

• Preferred oral dose: 75-100 mg/kg/day in 3 or 4 doses 2
• For this 61.46 kg child: 4,609-6,146 mg/day divided into 3-4 doses
• However, the maximum adult dose is 4,000 mg/day 2, 1
• Practical recommendation: 1,000 mg (20 mL) every 6 hours = 4,000 mg/day

For Otitis Media

• Clinical studies show 75 to 100 mg/kg/day in 4 divided doses is required 1
• For this child: approximately 1,150-1,500 mg (23-30 mL) every 6 hours
• Capped at maximum 4,000 mg/day

For Streptococcal Pharyngitis or Uncomplicated Skin Infections

• May use twice-daily dosing 1
• 750-1,000 mg (15-20 mL) every 12 hours

Important Considerations

Maximum Dose Limitations

• The adult maximum dose is 4,000 mg/day 2, 1
• At 61.46 kg, this child is approaching adult weight, so adult maximum doses apply
• If daily doses greater than 4 g are required, parenteral cephalosporins should be considered 1

Duration of Therapy

• β-hemolytic streptococcal infections: minimum 10 days 1
• Uncomplicated cystitis: 7-14 days 1
• Most other infections: 5-10 days depending on clinical response

Storage and Preparation

• After mixing the suspension, store in refrigerator 1
• May be kept for 14 days without significant loss of potency 1
• Shake well before each use

Alternative Dosing Frequencies

Recent evidence supports less frequent dosing regimens to improve adherence:

• Three times daily dosing: 45 mg/kg/dose (maximum 1.5 g) has shown efficacy and tolerability in bone and joint infections 3
• For this 61.46 kg child: 1,500 mg (30 mL) three times daily (capped at maximum 1,500 mg/dose)
• Twice-daily dosing: 22-45 mg/kg/dose for MSSA with MIC 1-2 mg/L 4

Final Practical Recommendation

Standard approach for most infections:

• 500 mg (10 mL of 250 mg/5 mL suspension) every 6 hours = 2,000 mg/day

For more severe infections or confirmed S. aureus:

• 1,000 mg (20 mL) every 6 hours = 4,000 mg/day (maximum dose)

For improved adherence (if appropriate for the infection type):

• 1,500 mg (30 mL) three times daily = 4,500 mg/day (exceeds typical maximum but supported by recent evidence for specific indications) 3