Rx Update: October 2004
Joan Murhammer, R.Ph., Mary Ross, R.Ph., M.B.A., Kevin Bebout,
R.Ph.
Peer Review Status: Internally Reviewed
Ertapenem
Ertapenem (Invanz®) is a carbapenem antibiotic indicated for the treatment of complicated intra-abdominal infections, complicated skin and skin structure infections, community-acquired pneumonia, complicated urinary tract infections, and acute pelvic infections due to susceptible organisms. It has a broad spectrum of activity against both gram-positive and gram-negative aerobic and anaerobic bacteria, but unlike other carbapenems (e.g., meropenem, imipenem-cilastatin), it does not cover hospital-acquired pathogens such as Pseudomonas and Acinetobacter, and should not be used for nosocomial infections or Enterococcus infections.
The most common adverse events with ertapenem therapy are diarrhea, nausea, headache, vaginitis in females, phlebitis/thrombophlebitis, and vomiting. Seizures have been reported in 0.5% of patients treated with ertapenem. Seizures occur most frequently in patients with brain lesions or a history of seizures and/or renal dysfunction. Ertapenem is contraindicated in patients with a known hypersensitivity to ertapenem or other carbapenems and in patients who have had an anaphylactic reaction to other beta-lactams (e.g., penicillins, cephalosporins). The intramuscular route is contraindicated in patients allergic to amide-type local anesthetic agents since lidocaine is used as the diluent.
The recommended dose of ertapenem for adults is 1 gm intravenously or intramuscularly once daily. The duration of therapy depends on the indication for use and ranges from 3 to 14 days. In patients with renal dysfunction (CrCl < 30 ml/min), the recommended dose is 500 mg once daily. A supplemental dose of 150 mg is required post-dialysis for patients on hemodialysis, if the daily dose is administered within 6 hours prior to the dialysis session.
For intravenous administration, ertapenem is diluted in NS 50 ml and administered over 30 minutes. The drug is not compatible with dextrose-containing solutions. For intramuscular administration, the drug is reconstituted with 1% lidocaine injection and should be injected into a large muscle mass (e.g., gluteal muscle or lateral part of thigh muscle).
PROBLEM: When doses of single ingredient liquid medications (oral or parenteral) are expressed by volume alone, the risk of serious medication errors increases. For example, an order for a liquid medication with the dose expressed in milliliters (mL) rather than milligrams (mg), micrograms (mcg), units or grams can easily lead to transcription and dispensing errors that may culminate in a drug overdose. This can be especially problematic if the medication is available in multiple concentrations; inadvertant use of the wrong product to fulfill an order prescribed by volume alone can also lead to significant drug overdoses (or under dosages).
SAFE PRACTICE RECOMMENDATION: To reduce the possibility of medication errors, it's critical for prescribers to use metric weight, not just the volume, for liquid medication doses. If orders are received without the dose expressed in metric weight, pharmacists and nurses should always clarify the intended concentration with the prescriber. Similarly, doses transcribed to medication administration records or other medication profiles should always be written using metric weight. [Note: orders written for multiple-ingredient liquid medications may be written using volume when it is clearly understood which drug product is being prescribed.]
Additional information about safely prescribing medications at the UIHC can be found in the following hospital policies located on the UIHC Policies and Procedures Web Site: 1.23 -- Prescribing Medications for Hospitalized Patients (Inpatients) and Clinic Patients and 1.17 -- Prescribing "Take Home" Medications for Clinic Patients or for Inpatients at the Time of Discharge (Ambulatory Care Patients).