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Zerbaxa Labels Cause Confusion Over Dosages

— May 21, 2015

Puzzled male shrugging wearing lab coat


The FDA announced yesterday that it is warning healthcare professionals of potential problems with Zerbaxa (ceftolozane and tazobactam). Apparently, the Zerbaxa labels cause confusion over dosages. The risk stems from the vial label being approved with each individual active ingredients’ strength listed (e.g. 1 g/0.5 g). The product is not dosed like that, though, and the carton label shows the correct dose. Instead, actual dosing is based on the sum of the two ingredients (e.g. 1.5 g). In future, the vial label will show the sum of the two ingredients. (See the Drug Safety Communication for Label Photos).

There have been seven reported cases to date of dosing errors during preparation of the drug in the pharmacy caused by this labeling error. Most drugs in this class (beta-lactam/beta-lactamase) list strength as the sum of the two active ingredients. Thus, in some instances, patients were getting 50% more than actually prescribed. No adverse effects have been reported.

Zerbaxa treats difficult urinary tract infections, as well as abdominal infections when used in conjunction with metronidazole, an antibacterial drug.

The FDA requests that patients and healthcare providers report any medication errors or side effects from Zerbaxa to the FDA MedWatch Safety Information and Adverse Event Reporting Program using any of the following methods:

  • Complete and submit the report Online:
  • Download form or call 1-800-332-1088 to request a reporting form, then complete and return to the address on the pre-addressed form, or submit by fax to 1-800-FDA-0178


Zerbaxa (ceftolozane and tazobactam): Drug Safety Communication – FDA Cautions About Dose Confusion and Medication Errors

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