Stephanie Lager, Betsy White, Megan Baumann, Randall E Mitchem, Ronna Jackson, and Nicola Black

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BACKGROUND: When carbapenems were first introduced, it was recommended to use them cautiously in patients with a penicillin allergy due to an approximately 50% potential risk of cross-sensitivity in these patients. Carbapenems have a broad spectrum of coverage and may be necessary for treatment of acutely ill patients; however, clinicians may avoid the use of carbapenems in patients with a documented penicillin allergy.

OBJECTIVE: To further define the risk of cross-sensitivity to carbapenems in patients with a penicillin allergy that has been documented in the electronic medical record or has been self-reported.

Methods: Ninety-five patients with a documented or self-reported penicillin allergy were evaluated for the risk of carbapenem cross-sensitivity. Allergy information was obtained from a patient interview by a pharmacist or from the electronic medical record. Patients were evaluated for the type of allergic reaction, time of onset, and the carbapenem administered. The primary endpoint of the study was to determine the incidence of carbapenem cross-sensitivity in patients with a penicillin allergy.

Results: Twenty-eight patients (29%) with a penicillin allergy were interviewed about their allergy, the reaction type, and the date of onset. The other 67 patients were not interviewed due to lack of clinical services or because the patient was unable to communicate. Two (2.1%) of the 95 patients were positive for an allergic reaction to a carbapenem.

CONCLUSIONS: This research study supports recent findings that the incidence of carbapenem cross-sensitivity is low in patients with a penicillin allergy that is self-reported or documented in the electronic medical record. The benefits of using a carbapenem in penicillin-allergic patients may outweigh the potential risks. Based on these findings, our dispensing algorithm was modified.

J Pharm Technol 2009;25:159-63