What is the recommended dose of meropenem (Merrem) for adults and pediatric patients with normal and impaired renal function?

Meropenem Dosing Recommendations

Adults with Normal Renal Function

For adults with normal renal function, administer meropenem 500 mg IV every 8 hours for skin and skin structure infections, or 1 gram IV every 8 hours for intra-abdominal infections and severe infections. 1

• For severe infections including hospital-acquired pneumonia, ventilator-associated pneumonia, and carbapenem-resistant Enterobacterales bloodstream infections, use 1 gram IV every 8 hours by extended infusion over 3 hours 2
• Standard infusion time is 15-30 minutes, though doses of 1 gram may be given as IV bolus over 3-5 minutes 1
• Extended 3-hour infusions are specifically recommended when treating organisms with MIC ≥4-8 mg/L to optimize pharmacokinetic/pharmacodynamic properties 3, 2
• ICU patients with preserved renal function often require higher doses due to increased clearance and altered volume of distribution 2

Adults with Renal Impairment

Maintain the full 1 gram dose per administration when possible, but extend the dosing interval rather than reducing individual doses, as smaller doses may reduce efficacy. 3, 4

Dosing Algorithm by Creatinine Clearance:

• CrCl >50 mL/min: Standard dose every 8 hours 1
• CrCl 26-50 mL/min: Standard dose every 12 hours 1
• CrCl 10-25 mL/min: Half the standard dose every 12 hours 1
• CrCl <10 mL/min: Half the standard dose every 24 hours 1

Critical Considerations for Dialysis:

• Intermittent hemodialysis removes approximately 50% of meropenem—always administer doses after dialysis sessions to avoid premature drug removal and ensure adequate exposure 3
• For CRRT patients, use 1 gram every 8-12 hours as CRRT removes 25-50% of meropenem and CVVHDF removes 13-53% 3
• For SLED, maintain the full 1 gram dose every 12 hours rather than reducing below 1 gram 4
• The elimination half-life increases from approximately 1 hour in normal renal function to 2.5-8.7 hours in renal impairment 3, 5

Safety Monitoring in Renal Impairment:

• Target trough concentrations below 64 mg/L to prevent neurological toxicity, particularly seizures 4, 2
• Therapeutic drug monitoring is recommended for critically ill patients with renal impairment and those on renal replacement therapy 3, 2
• Meropenem has lower pro-convulsive activity compared to imipenem, making it safer in renal dysfunction 3

Pediatric Patients (≥3 Months)

Dose based on infection type: 10 mg/kg every 8 hours for skin/skin structure infections, 20 mg/kg every 8 hours for intra-abdominal infections, and 40 mg/kg every 8 hours for meningitis (maximum 2 grams per dose). 6, 1

• For children weighing >50 kg, use adult dosing: 500 mg every 8 hours for skin infections, 1 gram every 8 hours for intra-abdominal infections, and 2 grams every 8 hours for meningitis 1
• When treating skin/skin structure infections caused by P. aeruginosa, increase to 20 mg/kg (or 1 gram if >50 kg) every 8 hours 1
• Administer as IV infusion over 15-30 minutes or as IV bolus over 3-5 minutes 1
• Limited safety data exists for 40 mg/kg bolus dosing 1

Pediatric Patients (<3 Months)

Dosing is based on gestational age (GA) and postnatal age (PNA) for complicated intra-abdominal infections, administered as 30-minute IV infusion. 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

Common Pitfalls to Avoid

• Never reduce individual doses below 1 gram in adults with serious infections, even in renal impairment—instead extend the dosing interval 4
• Never administer meropenem before dialysis sessions, as this leads to premature drug removal and subtherapeutic levels 3
• Avoid underdosing in ICU patients with normal renal function who have increased clearance and volume of distribution 2
• Do not use continuous infusion without considering drug stability—meropenem requires preparation of new infusion bags every 6 hours at room temperature 2
• Reconstituted solutions for bolus administration may be stored up to 3 hours at room temperature or 13 hours refrigerated 1
• Solutions prepared for infusion with 0.9% sodium chloride may be stored 1 hour at room temperature or 15 hours refrigerated; solutions with 5% dextrose should be used immediately 1