ERTAPENEM (INVANZ) - A NEW PARENTERAL CARBAPENEM
[The Medical Letter 2002;44:25]:
The drug is a new carbapenem, similar to imipenem and meropenem that was approved by the FDA for once daily IV treatment of intra-abdominal, urinary tract, soft tissue, and acute pelvic infections and community-acquired pneumonia. Compared to imipenem and meropenem, the following differences are highlighted:
- Ertapenem is highly protein bound and has a half-life of four hours compared to the alternatives with half-life of about one hour. Thus, it can be given once daily rather than three or four times daily.
- The spectrum of activity is similar with broad activity against many bacteria including anaerobes with two important exceptions: ertapenem has little activity against P. aeruginosa or Acinetobacter (AAC 2001;45:2831;AAC 2002;46:220).
- Therapeutic trials have shown equivalence with other standard treatments for intra-abdominal sepsis, serious soft tissue infections, pelvic infections, community-acquired pneumonia, and complicated urinary tract infections. The comparators in these trials were piperacillin/tazobactam or ceftriaxone; all studies had substantial sample sizes and showed comparable outcomes in the two groups as summarized in Table 1.
Average wholesale price for Ertapenem at 1 gm/day was listed at $47.69, which was substantially lower than imipenem at 500 mg q6h ($122.92), meropenem at 1 gm q8h ($155.52), and somewhat lower in price compared to piperacillin/tazobactam at 3 gm (piperacillin) q6h ($66.12) or ceftriaxone at 1 gm/day ($50.24).
- The drug was “generally well tolerated” with seizures in 0.5% of patients.
The conclusion is that this drug offers better anaerobic coverage than ceftriaxone and fewer daily doses compared to betalactam-bectalactamase inhibitors (Zosyn, Timentin), it has no apparent advantages over ceftriaxone for treatment of CAP and, unlike imipenem or meropenem, it lacks activity against Pseudomonas and Acinetobacter. It offers a good option for home therapy and selected other settings.