FDA: Today's change to heparin standard will lead to 10% potency reduction

The FDA notified healthcare professionals and patients of a change to heparin, effective today, which will include a new reference standard and test method used to determine the potency of the drug and detect impurities that may be present. The change will result in 10 percent reduction in the potency of the heparin marketed in the U.S., according to the agency.

Healthcare providers should be aware of the decrease in heparin potency as they monitor the anticoagulant effect of the drug; more heparin may be required to achieve and maintain the desired level of anticoagulation in some patients. Also, the agency said this may have clinical significance in some situations, such as when heparin is administered as a bolus IV dose and an immediate anticoagulant effect is clinically important.

The change also will harmonize the USP unit dose with the World Health Organization’s International Standard Unit dose. There will be simultaneous availability of heparin manufactured to meet the “old” and “new” USP monograph, with potential differences in potency. Products using the new “USP unit” potency definition are anticipated to be available on or after Oct. 8.

The FDA said it is working with the manufacturers of heparin to ensure that an appropriate identifier is placed on heparin made under the new USP monograph. Most manufacturers will place an “N” next to the lot number.

The agency also said it is working with the heparin manufacturers to study the impact of this variation in potency and will make the results available when the studies have concluded.