What is the recommended dose of Meropenem (generic name) for a 42-year-old female patient with severe impaired renal function (creatinine level of 5.5)?

Meropenem Dosing in Severe Renal Impairment

For a 42-year-old female with a serum creatinine of 5.5 mg/dL (indicating severe renal impairment with estimated creatinine clearance <30 mL/min), meropenem should be dosed at 500 mg every 24 hours, or 1000 mg every 24 hours for severe infections, unless the patient is receiving renal replacement therapy. 1, 2

Estimating Renal Function

• With a serum creatinine of 5.5 mg/dL in a 42-year-old female, the estimated creatinine clearance is likely <10-15 mL/min, placing her in the severe renal impairment or end-stage renal disease category 2
• Standard dosing of meropenem (1000 mg every 8 hours) would result in drug accumulation and potential toxicity in this patient 1

Recommended Dosing Regimen

For creatinine clearance <30 mL/min (not on dialysis):

• Standard infections: 500 mg every 24 hours 1, 2
• Severe infections or pathogens with MIC ≥2 mg/L: 1000 mg every 24 hours 1
• The terminal half-life of meropenem is prolonged from 1 hour in healthy individuals to 10-13.7 hours in anuric patients 1, 2

If Patient is on Hemodialysis

• Administer 500 mg after each hemodialysis session 1, 2
• Approximately 50% of meropenem is removed during a hemodialysis session 1
• The dialysis clearance is approximately 81 mL/min 2
• Do not give supplemental doses between dialysis sessions unless treating severe infections 2

If Patient is on Continuous Renal Replacement Therapy (CRRT)

For continuous venovenous hemofiltration (CVVHF):

• 500 mg every 8-12 hours is appropriate for most infections 3, 4
• For severe infections or pathogens with MIC ≥4 mg/L: consider 1000 mg every 8 hours or continuous infusion 4
• CVVHF removes 25-50% of meropenem, with hemofiltration clearance of approximately 22 mL/min 1, 3
• The terminal half-life during CVVHF is approximately 8.7 hours 3

For continuous venovenous hemodiafiltration (CVVHDF):

• Similar dosing to CVVHF, though CVVHDF may remove 13-53% of the drug depending on treatment parameters 1

Critical Considerations for Severe Infections

• For infections caused by pathogens with MIC ≥8 mg/L, standard dosing may be insufficient even with dose adjustments 4
• Consider continuous infusion (1000-2000 mg over 24 hours) for critically ill patients with severe infections and preserved residual renal function 4
• Target attainment of 100% time above MIC is only achieved in 48.4% of critically ill patients with standard dosing when MIC is 2 mg/L 5

Monitoring Parameters

• Check renal function (serum creatinine and estimated creatinine clearance) at baseline and monitor during therapy 2
• For patients with fluctuating renal function, reassess dosing every 2-3 days 5
• Monitor for signs of drug accumulation, particularly neurological symptoms (seizures can occur with excessive meropenem levels) 1

Common Pitfalls to Avoid

• Do not use standard dosing (1000 mg every 8 hours) in patients with creatinine clearance <30 mL/min, as this will lead to drug accumulation 1, 2
• Do not rely solely on serum creatinine without calculating creatinine clearance, especially in patients with low muscle mass 6
• Do not underdose in patients on CRRT—the recommended dose should be increased by up to 100% compared to anuric patients not receiving renal replacement therapy 3
• Recognize that meropenem and its metabolite are effectively removed by hemodialysis, requiring post-dialysis dosing 2