What is the preferred route of administration for Invanz (Ertapenem), intramuscular (IM) or intravenous (IV)?

Ertapenem Administration: IV vs IM Route

Intravenous (IV) administration is the preferred route for ertapenem (Invanz), but intramuscular (IM) administration is an appropriate alternative when IV access is limited or unavailable. 1

Administration Guidelines

• Ertapenem may be administered by IV infusion for up to 14 days or IM injection for up to 7 days 1
• When administered intravenously, ertapenem should be infused over a period of 30 minutes 1
• IM administration can be used as an alternative to IV administration for infections where intramuscular therapy is appropriate 1
• The standard adult dose is 1 gram given once daily, regardless of administration route 1

Bioavailability and Pharmacokinetics

• IM ertapenem has approximately 92% bioavailability compared to IV administration 2
• When reconstituted with 1% lidocaine HCl injection (in saline without epinephrine), IM ertapenem is almost completely absorbed 1
• Following IM administration, mean peak plasma concentrations are achieved in approximately 2.3 hours 1
• Although maximum serum concentration is somewhat lower with IM administration, the overall plasma concentration profiles are comparable to IV administration at later time points 2

Clinical Considerations for Route Selection

• IV administration is preferred for:

  • Critically ill patients requiring rapid achievement of therapeutic levels 3
  • Treatment courses longer than 7 days 1
  • Patients with severe infections requiring precise dosing 4

• IM administration is appropriate for:

  • Settings where vascular access is limited or unavailable 3
  • Outpatient antimicrobial therapy when IV access is challenging 5
  • Patients who can be treated for 7 days or less 1

Practical Considerations

• IM injections can be painful and may not be suitable for all patients 2
• For necrotizing infections of the skin, fascia, and muscle, ertapenem is listed as an appropriate treatment option at 1g daily IV 4
• When treating mixed infections, ertapenem can be administered at 1g daily IV or 15 mg/kg/dose every 12 hours IV for children 3 months to 12 years 4

Conclusion

While both routes are effective for delivering ertapenem, IV administration remains the primary route of choice for most clinical scenarios due to more predictable pharmacokinetics and longer treatment duration capability (up to 14 days vs 7 days for IM). However, IM administration provides a valuable alternative when IV access is problematic, with the benefit of maintaining high bioavailability (92%) compared to IV dosing 1, 2.