Meropenem Dosing in Adults with Impaired Renal Function
For adults with impaired renal function, meropenem dosing must be adjusted based on creatinine clearance: use the recommended dose (500 mg for complicated skin infections, 1 g for intra-abdominal infections) every 12 hours for CrCl 26-50 mL/min, half the recommended dose every 12 hours for CrCl 10-25 mL/min, and half the recommended dose every 24 hours for CrCl <10 mL/min. 1
Standard Dose Adjustment Algorithm by Renal Function
The FDA-approved dosing schedule provides clear thresholds for adjustment 1:
- CrCl >50 mL/min: Full recommended dose every 8 hours (500 mg for complicated skin/skin structure infections; 1 g for intra-abdominal infections) 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 Principle: Maintain Individual Dose Strength
When adjusting for renal impairment, extend the dosing interval rather than reducing individual doses below 1 gram for serious infections. 2 This approach preserves meropenem's concentration-dependent bactericidal effect, which is essential for optimal killing of pathogens 2, 3
The pharmacokinetic rationale is straightforward: meropenem's half-life increases significantly with declining renal function (from approximately 1 hour in normal function to 6+ hours in severe impairment), allowing for longer intervals between doses while maintaining therapeutic concentrations 4, 5
Special Populations Requiring Modified Approaches
Patients on Continuous Renal Replacement Therapy (CRRT)
For patients receiving CRRT or continuous venovenous hemodiafiltration (CVVHDF), use 1 gram every 8-12 hours 3, 6. CRRT removes 25-50% of meropenem, and CVVHDF removes 13-53%, necessitating higher doses than standard renal impairment adjustments 3. Research demonstrates that 1 g every 12 hours maintains trough levels above the MIC90 for most pathogens during CVVHDF 6
Patients on Sustained Low-Efficiency Dialysis (SLED)
Maintain the full 1 gram dose every 12 hours for patients on SLED 2, 3. Do not reduce individual doses below 1 gram, as this compromises the concentration-dependent killing effect 2
Patients on Intermittent Hemodialysis
Administer meropenem after dialysis sessions, as approximately 50% is removed during hemodialysis 3. Administering before dialysis leads to premature drug removal and subtherapeutic levels 3
Extended Infusion Considerations for Resistant Organisms
When treating infections with organisms having MIC ≥4-8 mg/L, use extended infusion over 3 hours even in renal impairment 7, 8. This optimizes pharmacokinetic/pharmacodynamic properties by maximizing the time that free drug concentrations remain above the MIC 7
For carbapenem-resistant Enterobacterales with meropenem MIC ≥8 mg/L, extended 3-hour infusion of 1 g every 8 hours is specifically recommended 7
Therapeutic Drug Monitoring (TDM)
TDM is strongly recommended in critically ill patients with renal impairment 8, 3. Target trough concentrations should remain below 64 mg/L to prevent neurological toxicity, particularly seizures 8, 2. Neurological deterioration occurs in approximately two-thirds of ICU patients when free trough concentrations normalized to the EUCAST breakpoint exceed 8 8
Monitor renal function indicators throughout treatment, though meropenem itself does not cause clinically significant renal toxicity 3
Common Pitfalls to Avoid
- Never reduce individual doses below 1 gram for serious infections in renal impairment—instead extend the dosing interval 2, 3
- Never administer meropenem before hemodialysis sessions—this causes premature drug removal and treatment failure 3
- Do not overlook the need for higher doses in CRRT patients—standard renal impairment dosing leads to underdosing 3, 6
- Avoid underdosing in critically ill patients with preserved renal function—these patients often have increased clearance requiring higher doses 8
Administration Methods
Meropenem can be administered as 1:
- 15-30 minute intravenous infusion (standard method) 1
- 3-5 minute intravenous bolus injection (5-20 mL) 1
- 3-hour extended infusion (for resistant organisms with high MICs) 7, 8
When using continuous infusion, prepare new infusion bags every 6 hours due to limited drug stability at room temperature 8