What is the recommended dose of Merrem (Meropenem) for a patient with mild impaired renal function, specifically a Glomerular Filtration Rate (GFR) of 58?

Meropenem Dosing for Patient with GFR 58 mL/min/1.73m²

For a patient with a GFR of 58 mL/min/1.73m², the standard recommended dose of Meropenem should be used without adjustment, which is 500 mg every 8 hours for skin/soft tissue infections or 1 gram every 8 hours for intra-abdominal infections. 1

Dosing Based on Renal Function

Meropenem is primarily eliminated by the kidneys, making renal function an important consideration for dosing. The FDA-approved drug label provides clear guidance:

• GFR > 50 mL/min: Standard recommended dose (500 mg for skin/soft tissue infections or 1 gram for intra-abdominal infections) every 8 hours
• GFR 26-50 mL/min: Standard recommended dose every 12 hours
• GFR 10-25 mL/min: Half recommended dose every 12 hours
• GFR < 10 mL/min: Half recommended dose every 24 hours 1

Since this patient has a GFR of 58 mL/min, which falls into the "greater than 50 mL/min" category, no dose adjustment is required.

Pharmacokinetic Considerations

Meropenem has time-dependent bactericidal activity, with efficacy primarily related to the percentage of time that serum concentrations exceed the minimum inhibitory concentration (T>MIC) of the pathogen 2. With a GFR of 58 mL/min, the patient has mild renal impairment, but this level of kidney function is sufficient to maintain appropriate drug clearance.

Studies have shown that:

1. Meropenem's half-life is approximately 1 hour in healthy volunteers but can be prolonged in patients with decreased renal function 3
2. For patients with GFR > 50 mL/min, standard dosing provides adequate drug exposure to achieve therapeutic targets for most susceptible pathogens 4

Safety Considerations

Meropenem is generally well-tolerated in patients with mild renal impairment:

• Safety profiles in patients with mild renal impairment (GFR > 50 mL/min) are similar to those with normal renal function 5
• No increased risk of adverse events has been observed with standard dosing in this population 5

Special Considerations

If treating infections caused by Pseudomonas aeruginosa:

• Use the higher dose of 1 gram every 8 hours regardless of infection site 1

If the patient's renal function worsens during treatment (GFR drops below 50 mL/min):

• Reassess dosing and adjust according to the dosing table
• Consider therapeutic drug monitoring in critically ill patients to ensure adequate drug exposure 2

Administration

Meropenem can be administered as:

• Intravenous infusion over 15-30 minutes (preferred method)
• Intravenous bolus injection over 3-5 minutes (for doses of 1 gram or less) 1

By following these dosing recommendations, you can ensure optimal antimicrobial efficacy while minimizing the risk of adverse effects in a patient with mild renal impairment.