What is the recommended dose of meropenem (Merrem) for pediatric patients under 5 with complicated intra-abdominal infections, complicated skin/soft tissue infections, or bacterial meningitis?

Meropenem Dosing for Pediatric Patients Under 5 Years

For children under 5 years with complicated intra-abdominal infections or complicated skin/soft tissue infections, administer meropenem 20 mg/kg every 8 hours (maximum 1 gram per dose); for bacterial meningitis, use 40 mg/kg every 8 hours (maximum 2 grams per dose). 1

Age-Specific Dosing Algorithm

For Infants Less Than 3 Months of Age

The dosing strategy depends on both gestational age (GA) and postnatal age (PNA) 1:

• Infants <32 weeks GA and PNA <2 weeks: 20 mg/kg every 12 hours 1
• Infants <32 weeks GA and PNA ≥2 weeks: 20 mg/kg every 8 hours 1
• Infants ≥32 weeks GA and PNA <2 weeks: 20 mg/kg every 8 hours 1
• Infants ≥32 weeks GA and PNA ≥2 weeks: 30 mg/kg every 8 hours 1

These doses apply specifically to complicated intra-abdominal infections and should be administered as intravenous infusion over 30 minutes 1.

For Children 3 Months to Under 5 Years

Complicated Skin and Skin Structure Infections:

• 10 mg/kg every 8 hours (maximum 500 mg per dose) 1
• When treating Pseudomonas aeruginosa, increase to 20 mg/kg every 8 hours (maximum 1 gram per dose) 1

Complicated Intra-Abdominal Infections:

• 20 mg/kg every 8 hours (maximum 1 gram per dose) 2, 1
• This dose is also recommended as 60 mg/kg/day divided every 8 hours 2

Bacterial Meningitis:

• 40 mg/kg every 8 hours (maximum 2 grams per dose) 1

Administration Guidelines

• Infusion method: Administer over 15-30 minutes for standard dosing 1
• Bolus option: Doses may be given as IV bolus over 3-5 minutes, though there is limited safety data for 40 mg/kg bolus doses 1
• For infants <3 months: Always use 30-minute infusion 1

Important Clinical Considerations

Renal Impairment:

• No established dosing guidelines exist for pediatric patients with renal impairment 1
• Close monitoring is essential if meropenem must be used in this population 1

Duration of Therapy:

• Limit antimicrobial therapy to 4-7 days unless source control is difficult to achieve 2
• Longer durations have not been associated with improved outcomes 2

Dosing Optimization:

• Maximize β-lactam antibiotic dosages if undrained intra-abdominal abscesses may be present 2
• Initial inadequate antimicrobial therapy is associated with increased morbidity and mortality 2

Common Pitfalls to Avoid

• Underdosing Pseudomonas infections: Always use 20 mg/kg (not 10 mg/kg) for complicated skin/soft tissue infections when P. aeruginosa is suspected or confirmed 1
• Incorrect dosing intervals for young infants: Gestational and postnatal age must both be considered for infants <3 months 1
• Prolonged therapy without indication: Do not continue antibiotics beyond 7 days when adequate source control has been achieved 2
• Failure to adjust for weight: For children weighing >50 kg, use adult dosing (500 mg for cSSSI, 1 gram for cIAI, 2 grams for meningitis) 1