What is the recommended dose of Meropenem for a 67-year-old patient with impaired renal function and a creatinine level of 2.5?

Meropenem Dosing for a 67-Year-Old Patient with Creatinine 2.5 mg/dL

For this patient with a serum creatinine of 2.5 mg/dL, you should administer meropenem 500 mg every 12 hours (for complicated skin/soft tissue infections) or 1 gram every 12 hours (for intra-abdominal infections or severe infections), given intravenously over 15-30 minutes. 1

Critical First Step: Calculate Creatinine Clearance

• You must calculate the creatinine clearance (CrCl) using the Cockcroft-Gault equation rather than relying on serum creatinine alone, as serum creatinine significantly underestimates renal dysfunction, particularly in elderly patients 2
• For a 67-year-old patient with creatinine 2.5 mg/dL, the estimated CrCl will likely fall in the 26-50 mL/min range, placing this patient in the moderate renal impairment category 1

FDA-Approved Dosing Algorithm for Renal Impairment

The FDA prescribing information provides clear dosing based on calculated CrCl: 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 (most likely category for your patient)
• CrCl 10-25 mL/min: Half the standard dose every 12 hours
• CrCl <10 mL/min: Half the standard dose every 24 hours

Infection-Specific Dosing Considerations

For complicated skin and soft tissue infections: 1

• Standard dose is 500 mg every 8 hours with normal renal function
• However, if Pseudomonas aeruginosa is suspected or confirmed, increase to 1 gram every 8 hours (adjusted to every 12 hours if CrCl 26-50 mL/min) 1

For intra-abdominal infections: 1

• Standard dose is 1 gram every 8 hours with normal renal function
• Adjust to every 12 hours if CrCl 26-50 mL/min

Administration Method

• Administer as an intravenous infusion over 15-30 minutes 1
• Alternatively, may give as IV bolus injection (5-20 mL) over 3-5 minutes for adult patients 1

Critical Pitfalls to Avoid

Do not use standard dosing without adjustment: 1

• A serum creatinine of 2.5 mg/dL represents significant renal impairment requiring dose modification
• Failure to adjust dosing increases seizure risk, particularly in elderly patients with renal dysfunction 3

Seizure risk is real but rare when properly dosed: 3

• Meropenem-related seizures occurred in only 0.1% of patients with renal impairment when appropriately dosed
• The safety profile of meropenem in elderly and renally impaired patients is excellent when doses are adjusted 3

Monitor for underdosing in critically ill patients: 4

• Standard dosing may result in insufficient exposure in 48-80% of critically ill patients, depending on the pathogen's MIC 4
• If the patient is critically ill or septic, consider infectious disease consultation for potential therapeutic drug monitoring

Special Considerations for This Patient Population

Elderly patients (age 67) with renal impairment: 3

• Both 500 mg and 1 gram doses every 12 hours are generally well tolerated in this population
• The overall pattern and frequency of adverse events are similar to younger patients when doses are appropriately adjusted 3

If renal function is unstable or acute: 5

• The elimination half-life increases from 1.5 hours (normal function) to 3.4 hours (CrCl 30-50 mL/min) to 5.0 hours (CrCl <30 mL/min) 5
• Dosing intervals should be prolonged proportionally to the decline in CrCl 5

Hemodialysis considerations (if applicable): 5

• Hemodialysis significantly removes meropenem, shortening the elimination half-life from 7.0 hours to 2.9 hours 5
• Dose after each hemodialysis session if the patient is receiving intermittent hemodialysis 5