UPDATE: FDA Warns New Heparin Standards Will Cut Drug Potency

The U.S. Food and Drug Administration warned doctors about a manufacturing change in heparin that's expected to decrease the potency of the drug.

A top FDA official said more heparin may be needed for certain patients. John Jenkins, director of the FDA's Office Of New Drugs, said heparin is administered by health-care professionals and dosing is different for each patient.

The change, adopted by the United States Pharmacopeia, or USP, a nonprofit standards-setting organization, includes a revised reference standard for the drug's unit dose. The changes also require companies to test for a contaminant found in batches of Baxter International Inc.'s (BAX) heparin last year that was manufactured with tainted ingredients from China.

The change went into effect Thursday, but the FDA has asked four companies that market heparin in the U.S. to hold off shipping new heparin products until Oct. 8 to allow hospital pharmacies time to adjust dosing practices. Heparin is used in many surgery patients and patients undergoing kidney dialysis.

The FDA said the revised USP reference standard and unit definition for heparin is about 10% less potent than the former USP unit.

"Although the FDA-approved labeling for heparin has not changed, including the recommended doses, it is essential that health-care professionals be aware of the potential difference in potency between the old and new vials of heparin when administering the drug," Jenkins said.

The FDA said it's asked manufacturers identify their new products with a label change to help pharmacies and health-care professionals differentiate it from the former product. Both current products and new products made under the revised standards could co-exist for several months on hospital pharmacy shelves.

Jenkins explained that one of the manufacturers contacted the agency about three weeks ago after it found the heparin it made under the new USP standards was about 10% less potent than heparin made under the old standards. The agency contacted the other manufacturers who also found a similar change in potency.

The agency said APP Pharmaceuticalsis the largest heparin manufacturer in the U.S. and sells the product in vials. Hospira Inc. (HSP) markets heparin in intravenous bags, vials, and syringes while Baxter and B. Braun market heparin in intravenous bags.

-By Jennifer Corbett Dooren, Dow Jones Newswires; 202-862-9294; [e-mail]