What is the recommended dose of meropenem for an 85-year-old male with urosepsis and impaired renal function (serum creatinine 1.98)?

Meropenem Dosing for Elderly Patient with Urosepsis and Renal Impairment

For an 85-year-old male with urosepsis and serum creatinine of 1.98, the recommended meropenem dose is 500 mg every 12 hours based on the patient's estimated creatinine clearance of 26-50 mL/min. 1

Assessment of Renal Function

• First, calculate the patient's estimated creatinine clearance using the Cockcroft-Gault equation 1:
  • CrCl (mL/min) = [(140 - age) × weight (kg)] / [72 × serum creatinine (mg/dL)]
  • For an 85-year-old male with serum creatinine of 1.98 mg/dL, this likely falls in the 26-50 mL/min range (exact value depends on weight)

Meropenem Dosing Recommendations

• According to the FDA drug label, meropenem dosing should be adjusted based on creatinine clearance as follows 1:

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

• For urosepsis, the appropriate dose would be 1 gram (standard dose for serious infections) every 12 hours based on the patient's estimated creatinine clearance 1, 2

Administration Considerations

• Meropenem should be administered by intravenous infusion over approximately 15-30 minutes 1
• Alternatively, doses can be administered as an intravenous bolus injection over approximately 3-5 minutes 1
• For critically ill patients with higher MICs, extended infusion times (3-hour infusion) may be beneficial to maintain therapeutic concentrations 3

Special Considerations for Elderly Patients

• Elderly patients often have decreased renal function even with normal serum creatinine levels due to age-related decline in muscle mass 4
• The safety profile of meropenem in elderly patients (>65 years) and renally impaired patients (CrCl <51 mL/min) has been shown to be similar to younger patients 5
• Meropenem-related seizures are rare (0.1%), even in patients with renal impairment 5

Monitoring Recommendations

• Monitor renal function during therapy, especially in elderly patients whose renal function may change during the course of treatment 4
• Assess clinical response within 48-72 hours to determine efficacy 2
• For patients with fluctuating renal function, more frequent monitoring of creatinine clearance may be necessary to adjust dosing accordingly 3

Important Caveats

• If the patient is critically ill with augmented renal clearance (ARC) despite the elevated creatinine, higher doses may be needed 3
• If the patient is receiving continuous renal replacement therapy, different dosing would be required as approximately 47% of meropenem is removed through continuous venovenous hemofiltration 6
• For patients with Pseudomonas aeruginosa infections, higher doses (1 gram) may be warranted even with renal impairment, but the dosing interval should still be adjusted 1, 2

Practical Algorithm for Meropenem Dosing in Urosepsis

1. Calculate creatinine clearance using Cockcroft-Gault equation 1
2. Select dose based on CrCl and severity of infection 1:
   • For urosepsis: 1 gram is typically appropriate
   • Adjust interval based on renal function (every 12 hours for CrCl 26-50 mL/min)
3. Consider extended infusion (3 hours) for critically ill patients 3
4. Reassess renal function every 2-3 days and adjust dosing as needed 4