What is the recommended renal dose of meropenem for a patient with impaired renal function?

Meropenem Renal Dosing

For adults with impaired renal function, reduce both the dose and/or extend the dosing interval of meropenem based on creatinine clearance: maintain the full recommended dose (500 mg or 1 gram depending on infection type) but extend to every 12 hours for CrCl 26-50 mL/min, reduce to half the recommended dose every 12 hours for CrCl 10-25 mL/min, and reduce to half the recommended dose every 24 hours for CrCl <10 mL/min. 1

Standard Renal Dosing Algorithm for Adults

The FDA-approved dosing adjustments are structured as follows 1:

• CrCl >50 mL/min: Full dose (500 mg for cSSSI, 1 gram for intra-abdominal infections) every 8 hours 1
• CrCl 26-50 mL/min: Full recommended dose every 12 hours 1
• CrCl 10-25 mL/min: Half the recommended dose every 12 hours 1
• CrCl <10 mL/min: Half the recommended dose every 24 hours 1

Critical distinction: The FDA recommends maintaining the full individual dose and extending the interval for moderate impairment (CrCl 26-50 mL/min), rather than reducing the dose itself. 1 This preserves the concentration-dependent bactericidal activity of meropenem. 2

Special Considerations for Pseudomonas aeruginosa

When treating infections caused by P. aeruginosa, use 1 gram every 8 hours in patients with normal renal function, then apply the same renal adjustment algorithm to this higher base dose. 1 For example, a patient with CrCl 26-50 mL/min treating Pseudomonas would receive 1 gram every 12 hours. 2

Hemodialysis Dosing

For patients on intermittent hemodialysis, administer meropenem after each dialysis session, as approximately 50% of the drug is removed during a dialysis session. 2, 3, 4 The recommended approach is to give half the recommended dose every 24 hours, with dosing timed immediately post-dialysis. 4 Administering before dialysis leads to premature drug removal and subtherapeutic levels. 2

The elimination half-life during hemodialysis shortens from approximately 7.0 hours (off dialysis) to 2.9 hours (during dialysis). 4

Continuous Renal Replacement Therapy (CRRT)

For patients on CRRT, use 1 gram every 8-12 hours to compensate for continuous drug removal. 2 CRRT removes 25-50% of meropenem, while CVVHDF removes 13-53%, creating substantial variability. 2, 3 The wide range reflects differences in:

• CRRT modality (CVVHF vs CVVHDF) 3
• Effluent flow rates 2
• Residual renal function 2

Therapeutic drug monitoring is strongly recommended for all patients on CRRT to ensure adequate exposure and prevent toxicity. 2

Sustained Low-Efficiency Dialysis (SLED)

For SLED patients, maintain the full 1 gram dose every 12 hours. 2 The rationale is to preserve concentration-dependent killing while accounting for the prolonged elimination half-life (2.5-8.7 hours) in this setting. 2 Do not reduce the individual dose below 1 gram, as smaller doses may compromise efficacy. 2

Pediatric Renal Dosing

There is no established pediatric renal dosing for meropenem. 1 The FDA label explicitly states "there is no experience in pediatric patients with renal impairment." 1 For pediatric patients 3 months and older with normal renal function, standard dosing is 10 mg/kg (cSSSI), 20 mg/kg (intra-abdominal), or 40 mg/kg (meningitis) every 8 hours. 5, 1

Resistant Organisms and Extended Infusions

When treating organisms with MIC ≥4-8 mg/L, use extended 3-hour infusions even in renal impairment to optimize time above MIC. 2 For carbapenem-resistant Enterobacterales with meropenem MIC ≥8 mg/L, specifically use 1 gram over 3 hours every 8 hours (adjusted for renal function per the standard algorithm). 2

Extended infusions maximize the percentage of time that free drug concentrations remain above the MIC, which is the critical pharmacodynamic parameter for beta-lactams. 2

Common Pitfalls to Avoid

• Do not use meropenem with probenecid, as probenecid inhibits renal excretion and is not recommended. 1
• Monitor for neurological toxicity in renal impairment, particularly when trough concentrations exceed 64 mg/L. 2 However, meropenem has lower pro-convulsive activity than imipenem, making it safer in renal dysfunction. 2
• Reassess renal function regularly (every 2-3 days in unstable patients) to adjust dosing appropriately. 2
• Avoid underdosing in CRRT patients due to variable drug removal—when in doubt, use therapeutic drug monitoring. 2, 3

Evidence Quality Considerations

The FDA label provides the highest quality dosing guidance for standard renal impairment. 1 Research confirms that recommended dose reductions for meropenem result in drug exposure 158-286% higher than patients with normal renal function receiving regular doses, indicating the adjustments are appropriate and prevent toxicity. 6 Meropenem is the only renally cleared antibiotic with good-quality evidence supporting its dose reduction recommendations. 6