Imipenem Cannot Be Administered Orally
Imipenem is only available as an intravenous formulation and cannot be given by mouth. The FDA-approved drug label explicitly states that imipenem-cilastatin is "for intravenous use" only 1. All clinical guidelines and research consistently describe imipenem as an intravenous antibiotic without any oral formulation 2.
Why Imipenem Must Be Given Intravenously
- No oral formulation exists: The drug is manufactured only as a sterile powder for reconstitution and intravenous infusion 1
- Pharmacokinetic requirements: Imipenem requires intravenous administration to achieve therapeutic serum levels, with mean peak concentrations of 18.4 mcg/mL achieved 30 minutes after a 500 mg IV infusion 3
- Renal metabolism protection: Imipenem must be co-administered with cilastatin intravenously to prevent its rapid degradation by renal dehydropeptidase enzymes 1, 4
Clinical Context in Guidelines
When guidelines discuss transitioning from intravenous to oral therapy for various infections, imipenem is never mentioned as an oral option 2. For example:
- Mycobacterial infections: Guidelines describe an "intensive phase" using intravenous imipenem, followed by a "continuation phase" with oral antibiotics (macrolides, linezolid, clofazimine, moxifloxacin)—but imipenem itself is discontinued, not converted to oral form 2
- Intra-abdominal infections: When oral step-down therapy is appropriate, imipenem is replaced with entirely different oral agents 2
Common Clinical Pitfall
Do not confuse imipenem with ertapenem, another carbapenem that also requires intravenous administration. Neither has an oral formulation, despite both being beta-lactam antibiotics 2. If oral therapy is needed, alternative antibiotic classes must be selected based on the specific pathogen and susceptibility patterns 2.