Health professional risk communication

PRIMAXIN 500 (imipenem and cilastatin sodium) for injection - Incorrect Labelling Information

Starting date:
September 6, 2016
Posting date:
September 6, 2016
Type of communication:
Dear Healthcare Professional Letter
Source of recall:
Health Canada
Important Safety Information
Healthcare Professionals, General Public
Identification number:


Healthcare professionals including physicians, pharmacists, pharmacy technicians and nurses in hospitals. Please distribute this communication to the appropriate personnel within your facility who are using this product.

Retail pharmacists that reconstitute and dilute the product for ambulatory care purposes and healthcare professionals who may reconstitute and dilute the product in a home care setting for patient administration.

Key messages

  • The label on the outer package of PRIMAXIN 500 (imipenem and cilastatin sodium) contains incorrect information regarding the final diluted concentration after reconstitution. It indicates the diluted concentration is 2.5 mg/mL instead of 5 mg/mL (when prepared as per the instructions in the package insert). Referencing this incorrect information could lead to a potential dosing error.
  • Healthcare professionals are directed to consult the package insert or the Canadian Product Monograph for the proper reconstitution and dilution instructions.



The label on the outer package of PRIMAXIN 500 (imipenem and cilastatin sodium) contains incorrect information. The label incorrectly states: “Use reconstituted solution (2.5 mg/mL) within 4 hours if kept at room temperature (15°C – 30°C) or within 24 hours if refrigerated (2°C – 8°C).” (see image below of the incorrect label on the outer package). In fact, when reconstituted and diluted as directed, the final concentration (expressed as imipenem content) will be 5 mg/mL, not 2.5 mg/mL as written above. If the outer package label were relied upon in product administration, this labelling error could possibly result in a patient receiving a double dose of imipenem/cilastatin.

The strength of the product (500 mg) as displayed on the outer package, the vial label and the package insert as well as the reconstitution and dilution instructions in the package insert/Canadian Product Monograph are correct.

Products affected

Products affected
PRIMAXIN® 500 (imipenem and cilastatin sodium) 00717282 25 vials/box 2204290 Oct-17
2207460 Nov-17
M031928 May-18
M032243 May-18

Background information

PRIMAXIN is a broad spectrum beta-lactam antibiotic. PRIMAXIN is indicated for the treatment of the following serious infections due to susceptible organisms: intra-abdominal infections, lower respiratory tract infections, gynecological infections, septicemia, urinary tract infections, bone and joint infections, skin structure infections, and endocarditis caused by S. aureus.

This product is not for direct infusion. It must be reconstituted and further diluted before use.

Who is affected

Advice for consumers

Patients receiving this product in a home care setting should consult with their healthcare professional to confirm that they are receiving the correct dose of their medication.

Information for health care professionals

The PRIMAXIN Canadian Product Monograph and package insert contain the accurate product reconstitution procedures and should always be followed by health care practitioners.

The Product Monograph/package insert mentions the following:

Reconstitution: PRIMAXIN is supplied in vials of 500 mg imipenem equivalent and cilastatin equivalent when reconstituted. Contents of the vials must be suspended and transferred to 100 mL of an appropriate infusion solution. A suggested procedure is to transfer approximately 10 mL from the 100 mL of the appropriate infusion solution to the vial. Shake well. Return the resulting 10 mL of suspension to the remaining 90 mL of the infusion solution. Repeat, using 10 mL of the diluted suspension, to ensure complete transfer of the contents of the vial to the infusion solution.

Central nervous system (CNS) adverse experiences such as myoclonic activity, confusional states, or seizures have been reported with PRIMAXIN especially when recommended dosages based on renal function and body weight were exceeded. These experiences have occurred most commonly in patients with CNS disorders (e.g., brain lesions or history of seizures) and/or who have compromised renal function. However, there were rare reports in which there was no recognized or documented underlying CNS disorder.

Action taken by Health Canada

Health Canada is communicating this important safety information to healthcare professionals via the Recalls and Safety Alerts Database on the Healthy Canadians Web Site. This communication will be further distributed through the MedEffect e-Notice email notification system. Health Canada is also monitoring the implementation of necessary corrective and preventive actions.

Report health or safety concerns

Managing marketed health product-related side effects depends on healthcare professionals and consumers reporting them. Any case of dosing error or other serious or unexpected side effects in patients receiving PRIMAXIN 500 (imipenem and cilastatin sodium) should be reported to Merck Canada Inc. or Health Canada.

Merck Canada Inc., Pharmacovigilance
16750 Trans-Canada Hwy.
Kirkland, Québec H9H 4M7
Fax: 1-800-369-3090

To correct your mailing address or fax number, contact Merck Canada Inc.

You can report any suspected adverse reactions associated with the use of health products to Health Canada by:

  • Calling toll-free at 1-866-234-2345; or
  • Visiting MedEffect Canada's Web page on Adverse Reaction Reporting for information on how to report online, by mail or by fax.

For other health product inquiries related to this communication, contact Health Canada at:
Regulatory Operations and Regions Branch
Telephone: 1-800-267-9675
Fax: 1-613-946-5636


Original signed by

Mauricio Ede, M.D.
Executive Director, Medical Affairs
® Merck Sharp & Dohme Corp. Used under license.


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