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  1. Postmarket Drug Safety Information for Patients and Providers

Question and Answers about Changes to the USP Heparin Monograph

The U.S. Food and Drug Administration (FDA) has alerted healthcare professionals to changes in the United States Pharmacopeia (USP) monograph for heparin products, effective October 1, 2009. Heparin made using the tests and reference standards in the new USP monograph will become available in healthcare facilities on or after October 8, 2009.

The following Questions and Answers provide additional information about heparin made using the tests and reference standards in the new USP monograph:

Q: How do these changes affect heparin?

A: Heparin manufactured after October 1, 2009 will be approximately 10% less potent than heparin manufactured prior to that date.  As of October 8, 2009, only heparin manufactured under this new monograph will be shipped by manufacturers.  To avoid any shortages, heparin manufactured and labeled using the old and new USP tests and reference standards will be simultaneously available in clinical settings for some period of time.  The heparin content and concentration on vials, bags and prefilled syringes will still be described as “USP Heparin Units”, despite the change in potency. 

Q:  Does the recent change affect all types of heparin products?
A: No.  The change affects only unfractionated heparin. 

Q: Why did USP change the monograph for heparin?

A: The USP changed its monograph as part of an ongoing effort to enhance the quality of heparin and to reduce the risk of having contaminated heparin on the market. The new monograph also includes new tests and procedures to help detect contaminants in the product. 

The change in how manufacturers test the potency of heparin will result in the USP Heparin Unit being harmonized with the international standard unit (IU).  Additional information regarding this change is available on the USP web sitedisclaimer icon.

Q: How can heparin products manufactured using the new USP tests and reference standard be distinguished from those manufactured under using the old USP tests and standards?

A: Depending on the manufacturer, the lot number or expiration date for heparin manufactured using the new USP tests and reference standard will contain various indicators (see table below). The manufacturers’ Websites will also contain details on how to determine whether the heparin product was manufactured using the new or old USP methods for heparin.


ManufacturerIndicators for Heparin made under New USP Monograph
APP"N" will follow the expiration date
Baxter"N" will precede the lot number
B Braun"N" will follow the lot number
HospiraThe first two digits of the lot number will begin with numbers > 82


Q: Have dosage recommendations for heparin changed?

A: No. The recommended doses of heparin described in the drug’s label have not changed.  Further, FDA does not recommend that clinicians automatically or routinely increase a patient’s heparin dose to compensate for the reduced potency of heparin made under the new USP monograph. Heparin dosing is individualized based on patient-specific considerations, given clinical dosing of heparin already varies among patients. The 10% change in potency should now be an additional consideration when determining heparin dose.  

Q: Are there clinical situations where a dosing adjustment should be made with heparin manufactured under the new USP monograph?

A: Maybe. In many clinical situations, a 10% decrease in heparin potency is not anticipated to have clinical consequences. However, there are some situations when a healthcare professional should carefully consider if the change in potency may be important in determining heparin dose. For instance, an increase in the dose of heparin may be necessary if heparin is administered intravenously as a bolus dose in order to achieve rapid anticoagulation (e.g., prior to a cardiovascular procedure), especially if aPTT/ACT monitoring is delayed or not performed prior to the procedure. 

For additional information, please see USP Heparin Informationdisclaimer icon.

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