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Heparin Less Potent, FDA Warns

Oct 2, 2009 | Parker Waichman Alonso LLP

Heparin, which has been reformulated following last year's contamination scandal, is not as potent as it once was.   The U.S. Food & Drug Administration (FDA) is warning doctors that some patients may now require more of the drug.

In 2008, Baxter International recalled prefilled heparin vials after they were linked to serious, and sometimes fatal, allergy-type reactions in some patients. There were similar recalls by other manufacturers in Denmark, Italy, France, Germany, and Japan. In total, tainted heparin was identified in 12 countries. It was eventually determined that a counterfeit ingredient in Chinese-sourced heparin was to blame for the problems.

According to a notice on the FDA's Web site, in response to the contamination problems, the United States Pharmacopeia (USP), a nonprofit standards-setting organization, has adopted new manufacturing controls for heparin to ensure the quality and to guard against potential contamination.  These changes include a modification of the reference standard for the drug’s unit dose, the FDA said.  The revised USP reference standard and unit definition for heparin is about 10 percent less potent than the former USP unit.

The change in heparin potency may have clinical significance in some situations, such as when heparin is administered as a bolus intravenous dose and an immediate anticoagulant effect is clinically important, the FDA said.  In such situations, the agency said healthcare providers should consider the change in potency of heparin when making decisions about what dose to administer.  The change in heparin potency is expected to be less clinically significant when it is administered subcutaneously due to the low and highly variable bioavailability of heparin when administered by this route.  Healthcare providers should also 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.

While the USP manufacturing controls take effect Oct. 1 for production, the FDA has asked manufacturers that they not ship this new product to customers until Oct. 8, 2009, or later. The delay will give health care providers and facilities time to learn about the changes and to make adjustments to their pharmacy procedures and dosing practices, the agency said.  It has also asked that all manufacturers identify their new products to help pharmacies and health care professionals differentiate it from the former product.

Four companies market heparin in the United States. APP, the largest manufacturer, markets heparin in vials; Hospira markets heparin in intravenous bags, vials, and syringes; Baxter markets heparin in intravenous bags, and B. Braun markets heparin in intravenous bags.