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Change in U.S. Pharmacopeia heparin monograph results in 10% potency decrease
New lots will be phased in as old lots are phased out during a transition period of several months.
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A change to the U.S. Pharmacopeia monograph for heparin will result in a decrease in the potency of heparin marketed in the United States and could have clinical implications in certain patient populations.
The change in the monograph, effective October 1, 2009, includes a new reference standard, as well as a new test method for the detection of additional impurities. The change will also harmonize the Pharmacopeia-recommended unit dose with that of the World Health Organization’s International Standard unit dose. The FDA has asked that heparin manufacturers delay shipment of heparin products manufactured and tested under the new monograph until October 8 or later in order to allow health care providers and pharmacies to make adjustments in their prescription and dispensing practices.
According to John K. Jenkins, MD, director of the Office of New Drugs at FDA, harmonization of the dosing standard would result in a 10% decrease in the potency per labeled unit of heparin marketed in the United States, and the change could have wider implications.
“This decrease in potency may have clinical implications in some patients, and may require dosage adjustments to increase the amount of heparin administered and more frequent patient monitoring to ensure that the desired anticoagulant effect is obtained,” Jenkins said during a press briefing. “This may be most critical when heparin is administered as a large bolus IV dose with the goal of achieving rapid therapeutic levels of anticoagulation.”
Clinical data from the manufacturer testing of the heparin products manufactured under the new standard, according to Jenkins, will not be available for a minimum of several weeks.
“The FDA does not currently have available data to assess the actual clinical impact of the change in potency standards for heparin manufactured under the new monograph, and therefore, we cannot make specific dosing recommendations for adjustments,” Jenkins said. “We are working with the manufacturers to conduct in vitro and animal studies to better understand the change and will report those results to the public as soon as they are available.”
According to a press release, FDA also alerted manufacturers and practitioners to make them aware of a new labeling system that will assist in the differentiation of older heparin products from newer heparin products manufactured after the monograph change. All four major manufacturers of heparin products will adjust their labeling in a manner that will allow new lots of heparin to be distinguished from lots manufactured before the monograph update. Three of the four manufacturers will begin placing the letter "N" at the beginning of their lot numbers or following the expiration dates of their new heparin products. Newer heparin products manufactured by Hospira will be identified by placing a number of "82" or greater at the beginning of the lot numbers.
The monograph change is part of a continuing update process initiated in 2007 after a significant quantity of heparin lots in the United States were found to be contaminated with impurities. – by Eric Raible
