What is the recommended dose of cephalexin (cephalexin) for a 170-pound child?

Cephalexin Dosing for a 170-Pound Child

For a 170-pound (77 kg) child, administer cephalexin 25-50 mg/kg/day divided into doses given every 6-12 hours depending on infection severity, which translates to approximately 500-1000 mg per dose when given four times daily, or 750-1500 mg per dose when given twice daily for appropriate infections.

Weight-Based Dosing Calculation

A 170-pound child weighs approximately 77 kg, which exceeds the typical pediatric weight range and approaches adult dosing thresholds. 1

Standard Pediatric Dosing Framework

• Usual recommended daily dosage: 25-50 mg/kg/day in divided doses 1
• For this 77 kg patient: This calculates to 1,925-3,850 mg total daily dose
• Dosing frequency options:
  • Four times daily (q6h): 500-1000 mg per dose 1
  • Twice daily (q12h): 1000-2000 mg per dose for appropriate infections 1

Infection-Specific Considerations

For skin and skin structure infections or streptococcal pharyngitis, the total daily dose may be divided and administered every 12 hours, allowing for twice-daily dosing at the higher end of the range. 2, 1

For more severe infections (such as bone and joint infections due to MSSA), higher dosing may be warranted:

• Recent evidence supports 45 mg/kg/dose (maximum 1,500 mg) three times daily for serious MSSA infections 3
• For this patient: approximately 1,375-1,500 mg three times daily 3, 4

Practical Dosing Recommendations

Standard Infections (Uncomplicated Skin/Soft Tissue, Pharyngitis)

• 500 mg every 12 hours (twice daily) is appropriate and FDA-approved for patients over 15 years 1
• This provides adequate coverage while improving adherence with less frequent dosing 2

Serious MSSA Infections (Bone/Joint Infections)

• 1,375-1,500 mg three times daily based on recent pharmacokinetic/pharmacodynamic studies 3, 4
• This achieves the target of free drug concentrations above MIC for ≥40% of the dosing interval 5, 4

Maximum Dosing Limits

• Adult maximum: 4 grams per day total 1
• If doses exceeding 4 grams daily are required, consider parenteral cephalosporins 1

Important Clinical Caveats

Renal function: Patients with creatinine clearance <30 mL/min require dose reduction proportional to decreased renal function 6

Treatment duration: For β-hemolytic streptococcal infections, continue therapy for at least 10 days 1

Tolerability: The higher three-times-daily dosing regimen (45 mg/kg/dose) is generally well tolerated, though mild gastrointestinal symptoms and neutropenia can occur in a small percentage of patients 3