Can ertapenem be administered intramuscularly, and what is the recommended duration of therapy?

Ertapenem Intramuscular Administration and Duration

Yes, ertapenem can be administered intramuscularly for up to 7 days, after which intravenous administration should be used if continued therapy is needed. 1

Route of Administration

Ertapenem may be given via two routes 1:

• Intravenous (IV) infusion: Up to 14 days
• Intramuscular (IM) injection: Up to 7 days maximum

The IM route serves as an alternative to IV administration only for infections where intramuscular therapy is appropriate. 1 The FDA label explicitly states that IM administration is limited to 7 days, while IV infusion can continue for up to 14 days. 1

Dosing Regimen

Adults and Pediatric Patients ≥13 Years

• Dose: 1 gram once daily (IV or IM) 1
• The bioavailability of IM ertapenem is 92% compared to IV administration 2

Pediatric Patients 3 Months to 12 Years

• Dose: 15 mg/kg twice daily (not to exceed 1 g/day) 3, 1

Duration by Indication

The total treatment duration varies by infection type 1:

• Complicated intra-abdominal infections: 5-14 days
• Complicated skin and skin structure infections (including diabetic foot infections without osteomyelitis): 7-14 days (up to 28 days for diabetic foot infections)
• Community-acquired pneumonia: 10-14 days
• Complicated urinary tract infections/pyelonephritis: 10-14 days
• Acute pelvic infections: 3-10 days

Important Clinical Considerations

Preparation and Administration

• Must be reconstituted with lidocaine for IM injection 4
• Do not use diluents containing dextrose 1
• Do not mix or co-infuse with other medications 1
• When given IV, infuse over 30 minutes 1

Tolerability

IM ertapenem reconstituted in lidocaine is generally well tolerated, with local injection site symptoms (primarily tenderness and pain) occurring in approximately 36% of patients, though moderate to severe symptoms are rare (1.1% in clinical trials). 4 The tolerability profile is comparable to IM ceftriaxone. 4, 5

Renal Impairment

For adult patients with creatinine clearance ≤30 mL/min/1.73 m², reduce the dose to 500 mg daily. 1 If ertapenem is given within 6 hours before hemodialysis, administer a supplementary 150 mg dose after the dialysis session. 1

Common Pitfall

The 7-day limit for IM administration is absolute per FDA labeling. 1 If therapy beyond 7 days is required, transition to IV administration. This limitation exists despite ertapenem not accumulating with repeated daily IM dosing over 7 days. 2