Imipenem Oral Formulation Availability
No, imipenem is not available in oral (pill) form in the United States—it is only available as an intravenous formulation for humans. 1
Available Formulations
Intravenous Administration
- Imipenem is exclusively available as an IV formulation in the United States, administered in combination with cilastatin 1
- Standard IV dosing ranges from 750-1250 mg every 6-8 hours depending on infection severity and suspected pathogens 2
- For serious infections, doses of 1000 mg every 6 hours are appropriate, or 1250 mg every 6 hours for suspected Pseudomonas or resistant organisms 2
Intramuscular Formulation (Historical)
- An intramuscular formulation was developed using a finely milled preparation that could be given in small volumes with favorable kinetics for 12-hourly dosing 3
- This IM formulation demonstrated 95% or greater favorable clinical outcomes for most body system infections in multicenter trials involving 686 patients 4
- The IM preparation was well tolerated in 87% of patients and provided effective treatment for mild to moderate infections at doses of 500-750 mg every 8-12 hours 5, 4
- However, this IM formulation is not mentioned in current guidelines and appears to have limited or no current availability 1
Alternative Carbapenem for Non-IV Routes
Ertapenem as the Preferred Alternative
- If IV access is unavailable and a carbapenem is necessary, ertapenem is the only carbapenem with an FDA-approved intramuscular formulation 6
- Ertapenem can be administered at 1g daily IM, with its longer half-life making once-daily dosing feasible 6
- The American Thoracic Society and Infectious Diseases Society of America recommend ertapenem as the alternative carbapenem for IM administration 6, 7
Clinical Implications
The absence of an oral imipenem formulation is due to pharmacokinetic limitations—beta-lactam antibiotics like imipenem require parenteral administration to achieve therapeutic concentrations 8, 9
Key Considerations:
- Never attempt to administer imipenem orally as no such formulation exists and oral bioavailability would be inadequate 1
- If oral therapy is needed, transition to an appropriate oral antibiotic based on culture sensitivities and clinical response 2
- For outpatient parenteral therapy requiring a carbapenem, consider ertapenem 1g IM daily rather than attempting imipenem administration 6, 7