Do you administer Ertapenem (a carbapenem antibiotic) daily, even on days when a patient with impaired renal function is not undergoing dialysis?

Ertapenem Dosing in Dialysis Patients

Yes, administer ertapenem daily (every 24 hours) even on non-dialysis days, but give it after dialysis on dialysis days to avoid premature drug removal. 1

Standard Dosing for Dialysis Patients

For patients with end-stage renal disease (ESRD) on hemodialysis, the FDA-approved dose is 500 mg once daily. 1 This represents a 50% reduction from the standard 1 gram daily dose used in patients with normal renal function. 1

Critical Timing Considerations

• When the daily dose is given within 6 hours before hemodialysis, administer a supplementary 150 mg dose (30% of the daily dose) after dialysis because approximately 30% of ertapenem is cleared during a hemodialysis session. 2
• On non-dialysis days, continue the 500 mg daily dose without interruption. 1 The once-daily dosing schedule is maintained throughout the week regardless of dialysis schedule because ertapenem has a sufficiently long half-life (14.1 hours in ESRD patients) to provide adequate coverage. 2

Pharmacokinetic Rationale

The pharmacokinetics of ertapenem are significantly altered in renal impairment. 2 In ESRD patients, the area under the curve increases by 192% and the half-life extends from 4.5 hours in healthy subjects to 14.1 hours. 2 This prolonged half-life supports once-daily dosing even on non-dialysis days. 3

Ertapenem's long half-life allows it to maintain serum concentrations above the MIC for most susceptible organisms for 12-24 hours, making it suitable for once-daily administration. 3

Critical Safety Warnings for Dialysis Patients

Risk of Neurotoxicity

The recommended 500 mg daily dose may still be excessive for some dialysis patients, particularly those with smaller body size or Asians, and can cause severe CNS toxicity. 4, 5

• Neurotoxicity manifests as hallucinations, asterixis, myoclonic jerks, cognitive impairment, and seizures. 4, 5
• Symptoms can develop after only 3-7 consecutive doses of the "recommended" 500 mg daily regimen. 5
• Plasma ertapenem levels can reach 53.7 mg/L (far exceeding the therapeutic MIC90 of 2 mg/L), and neurotoxicity can persist for up to 2 weeks even after drug discontinuation and high-flux hemodialysis. 4
• Ertapenem's high lipophilicity and CNS penetration contribute to sustained neurotoxicity that is difficult to reverse even with dialysis. 4

Monitoring Recommendations

Monitor closely for early signs of CNS toxicity (confusion, hallucinations, tremors) in all dialysis patients receiving ertapenem, especially after 3-4 days of therapy. 4, 5 Consider dose reduction below 500 mg daily or alternative antibiotics in patients with smaller body size or those showing early neurologic symptoms. 5

Common Pitfalls to Avoid

• Never administer ertapenem immediately before dialysis - this leads to premature drug removal and subtherapeutic levels. 2 Always give post-dialysis or ensure at least 6 hours between dose and dialysis session.
• Do not skip doses on non-dialysis days - the once-daily schedule should be maintained throughout the week to ensure continuous antimicrobial coverage. 1
• Do not assume the 500 mg dose is safe for all dialysis patients - this dose may still cause neurotoxicity, particularly in patients with smaller body size or after several consecutive days of therapy. 4, 5
• Do not use standard 1 gram doses in dialysis patients - the 158-192% increase in drug exposure necessitates dose reduction to 500 mg daily. 2