Important Changes for Heparin (December 2009)

FDA is notifying healthcare professionals and patients about a new USP monograph for heparin. Under the new monograph, the reference standard used to determine the potency of the drug will be changed in order to make it compatible with the WHO International Standard. Despite these changes in the reference standard, heparin dosages will continue to be expressed in USP units. Partly in response to the recent heparin contamination problem, the new monograph also includes additional test methods that can detect potential impurities and contaminants.

As a result of the change in the reference standard, the potency of heparin marketed in the U.S. will now be reduced by about 10 percent, so, there could be up to a 10 percent decrease in heparin activity for each USP unit administered. This means that some patients may require more heparin to achieve and maintain the desired level of anticoagulation. Patients may also require more frequent or intensive monitoring of aPTT or ACT.

This could be especially significant in some situations - for example, when heparin is administered as a bolus IV dose and it is important to achieve an immediate anticoagulant effect. The changes in heparin potency may not be clinically significant when it is given subcutaneously, because the drug's bioavailability is lower and more variable when it's administered this way.

Manufacturers began shipping the new heparin product in early October. For a while, both products will be available at the same time, to assure that there is an adequate supply for all patients. FDA has asked the manufacturers to label their heparin to differentiate between the old and new formulations.

FDA is working with heparin manufacturers to study the possible impact of reduced heparin potency on clinical care, and will share the results of these studies when they are available.

Category:

Science & Technology

Tags:

• Heparin
• FDA
• Dosage
• Test Methods
• Anticoagulation
• Patient Safety