From the FDA Drug Label
Ertapenem, reconstituted with 1% lidocaine HCl injection, USP (in saline without epinephrine), is almost completely absorbed following intramuscular (IM) administration at the recommended dose of 1 g. The mean bioavailability is approximately 90%. Following 1 g daily IM administration, mean peak plasma concentrations (Cmax) are achieved in approximately 2. 3 hours (Tmax).
The recommended IM dose of ertapenem is 1 g.
- Bioavailability: approximately 90%
- Time to reach peak plasma concentration (Tmax): approximately 2.3 hours 1
From the Research
The recommended dose of ertapenem for intramuscular (IM) administration is 1 gram once daily for adults. Before IM injection, ertapenem must be reconstituted with 3.2 mL of 1% lidocaine hydrochloride injection (without epinephrine) and then administered into a large muscle mass such as the gluteal muscles or lateral part of the thigh. The reconstituted solution should be used within 1 hour after preparation. For patients with renal impairment (creatinine clearance ≤30 mL/min), the dose should be reduced to 500 mg once daily. Ertapenem is a broad-spectrum carbapenem antibiotic effective against many gram-positive, gram-negative, and anaerobic bacteria, making it useful for complicated intra-abdominal infections, complicated skin and skin structure infections, community-acquired pneumonia, complicated urinary tract infections, and acute pelvic infections. The once-daily dosing is possible due to ertapenem's long half-life of approximately 4 hours, which allows for sustained antimicrobial activity over a 24-hour period.
Key Points to Consider
- The most recent study 2 does not directly address the dosing of ertapenem but highlights the importance of carbapenem stewardship in the treatment of extended-spectrum cephalosporin-resistant Enterobacterales infections.
- The pharmacokinetics of ertapenem support once-daily dosing, with a study from 2003 3 showing that the relative bioavailability of the 1-g IM dose is 92%, and ertapenem does not accumulate after multiple daily 1-g IM doses over 7 days.
- For patients with severe sepsis, the pharmacokinetics of ertapenem may be altered, with lower maximum plasma concentrations and higher volumes of distribution, as shown in a study from 2009 4.
- Ertapenem is suitable for outpatient parenteral antimicrobial therapy (OPAT) due to its once-daily dosing and broad-spectrum activity, as discussed in a study from 2004 5.
- The safety and local tolerability of IM ertapenem have been evaluated in a study from 2002 6, which found that ertapenem 1 g once daily IM was generally well tolerated, with a tolerability profile comparable to that of IM ceftriaxone therapy.
Administration and Dosage
- The dose of ertapenem for IM administration should be 1 gram once daily for adults, with adjustments for renal impairment.
- The reconstituted solution should be used within 1 hour after preparation and administered into a large muscle mass.
- Ertapenem's long half-life supports once-daily dosing, allowing for sustained antimicrobial activity over a 24-hour period.