What is the appropriate dosage of Ertapenem (a carbapenem antibiotic) for an 89-year-old female patient with impaired renal function, specifically a glomerular filtration rate (GFR) of 35?

From the Guidelines

For an 89-year-old female with a GFR of 35 mL/min, the recommended dosage of ertapenem is 1 gram once daily, as no dosage adjustment is required at this level of renal function, according to general medical knowledge and practices 1.

Key Considerations

• The patient's renal function is mildly impaired, but ertapenem dosage adjustment is typically required only when GFR falls below 30 mL/min.
• Ertapenem is administered via intravenous infusion over 30 minutes or as an intramuscular injection.
• The duration of therapy depends on the specific infection being treated, typically ranging from 3 to 14 days.
• Monitoring renal function during treatment is crucial, as elderly patients may experience fluctuations in kidney function.
• Common side effects of ertapenem include diarrhea, nausea, headache, and infusion site reactions.

Rationale

The provided evidence does not specifically address ertapenem dosage in patients with renal impairment. However, general medical knowledge and practices suggest that ertapenem dosage adjustment is not required for patients with a GFR of 35 mL/min 1.

Additional Considerations

• Ertapenem provides broad-spectrum coverage against many gram-positive, gram-negative, and anaerobic bacteria, but lacks activity against Pseudomonas and Acinetobacter species.
• The once-daily dosing of ertapenem makes it convenient for elderly patients, and its limited drug interactions profile is advantageous in older adults who may be on multiple medications.
• As people age, renal function declines, and the pharmacokinetics and pharmacodynamics of renally excreted drugs are altered in patients with impaired renal function 1.
• However, in this case, the patient's GFR is above the threshold for ertapenem dosage adjustment.

From the FDA Drug Label

1. 4 Patients with Renal Impairment Ertapenem for injection may be used for the treatment of infections in adult patients with renal impairment. In patients whose creatinine clearance is >30 mL/min/1.73 m2, no dosage adjustment is necessary. Adult patients with severe renal impairment (creatinine clearance ≤30 mL/min/1.73 m2) and end-stage renal disease (creatinine clearance ≤10 mL/min/1. 73 m2) should receive 500 mg daily.

The patient has a GFR of 35, which is greater than 30 mL/min/1.73 m2.

• No dosage adjustment is necessary for this patient.
• The recommended dose is 1 gram once daily. 2

From the Research

Ertapenem Dosage in Patients with Reduced Renal Function

• The dosage of ertapenem in patients with reduced renal function, such as a glomerular filtration rate (GFR) of 35, is an important consideration to ensure effective treatment and minimize potential adverse effects.
• According to the provided studies, there is no direct information on the dosage of ertapenem in an 89-year-old female patient with a GFR of 35 3, 4, 5, 6, 7.
• However, it is known that ertapenem is primarily excreted by the kidneys, and its dosage should be adjusted in patients with renal impairment.
• The studies provided do not offer specific guidance on ertapenem dosage in patients with a GFR of 35, but they do discuss the importance of considering renal function when using carbapenems, such as ertapenem and meropenem 3, 4, 5, 6, 7.

Considerations for Dosage Adjustment

• In general, the dosage of ertapenem may need to be adjusted in patients with renal impairment to prevent accumulation of the drug and potential adverse effects.
• The adjustment of ertapenem dosage in patients with reduced renal function should be based on the patient's creatinine clearance or GFR, as well as other factors such as age, weight, and concomitant medications.
• However, without specific guidance from the provided studies, it is not possible to determine the exact dosage of ertapenem that would be appropriate for an 89-year-old female patient with a GFR of 35.

Comparison with Other Carbapenems

• The provided studies compare the effectiveness of different carbapenems, including ertapenem and meropenem, in the treatment of various infections 5, 6, 7.
• While these studies do not provide specific guidance on ertapenem dosage in patients with reduced renal function, they do suggest that meropenem may be associated with a higher probability of clinical response and bacteriological response, as well as a reduced risk of serious adverse events, compared to other carbapenems 6.
• However, the study comparing ertapenem and meropenem for the treatment of ESBL-E bacteremia in critically ill patients found no difference in clinical failure between the two drugs 7.