What is the recommended dose of meropenem for a patient with normal kidney function, febrile neutropenia, and a weight of 35kg?

Meropenem Dosing for Febrile Neutropenia in 35kg Patient with Normal Renal Function

For a 35kg patient with febrile neutropenia and normal kidney function, administer meropenem 700 mg (20 mg/kg) intravenously every 8 hours as a 30-minute infusion. 1

Pediatric Dosing Framework

The dosing for this patient falls into the pediatric weight-based category since 35kg is below the typical adult threshold:

• Standard dose: 20 mg/kg every 8 hours for patients ≥3 months of age with normal renal function 1
• Calculated dose: 20 mg/kg × 35 kg = 700 mg every 8 hours
• Maximum single dose: 1 gram 1
• Administration: Intravenous infusion over 15-30 minutes 1, 2

Special Considerations for Febrile Neutropenia

Febrile neutropenic patients demonstrate altered pharmacokinetics that warrant attention:

• Increased volume of distribution: Neutropenic patients show significantly higher volumes of distribution (16.2 L/1.73 m²) compared to healthy subjects, which can reduce drug concentrations 3
• Enhanced nonrenal clearance: These patients exhibit increased nonrenal clearance [75 ml/(min × 1.73 m²)], potentially lowering drug exposure 3
• Pharmacodynamic target: Clinical response in febrile neutropenic bacteremia correlates with maintaining drug concentrations above the MIC for ≥75% of the dosing interval, with responders averaging 83% T>MIC versus 59% for non-responders 4

Dosing Interval Optimization

For Pseudomonas aeruginosa coverage specifically, consider shortening the interval:

• The guideline explicitly recommends 20 mg/kg (up to 1 gram) every 8 hours when treating complicated skin and skin structure infections caused by P. aeruginosa 1
• For this 35kg patient treating suspected or confirmed Pseudomonas: 700 mg every 8 hours remains appropriate, though some experts suggest every 6 hours for documented Pseudomonas infections in neutropenic patients 3

Critical Pitfalls to Avoid

• Do not underdose based on weight alone: The 20 mg/kg dosing is specifically designed for pediatric patients and should not be reduced arbitrarily 1
• Avoid bolus administration in this population: Use 15-30 minute infusions rather than 3-5 minute bolus injections to optimize pharmacodynamic parameters 1, 2
• Do not assume adult dosing applies: A 35kg patient requires weight-based dosing, not the standard adult 1 gram dose, unless treating highly resistant organisms 1
• Monitor for inadequate response: Given the altered pharmacokinetics in febrile neutropenia, if clinical response is suboptimal after 48-72 hours, consider increasing frequency to every 6 hours rather than increasing individual doses 3

Renal Function Monitoring

Since this patient has normal renal function currently:

• No dose adjustment is needed 2
• Meropenem is 70% renally eliminated, so monitor renal function during treatment 5
• If creatinine clearance drops below 50 mL/min during therapy, adjust to 700 mg every 12 hours 2