Clinicians should be aware of new manufacturing controls that have decreased the potency of the anticlotting agent heparin by up to 10%, according to the US Food and Drug Administration (FDA).
The changes in manufacturing standards for heparin were developed by the US Pharmacopeia (USP), a nonprofit standards-setting organization, and are enforced by the FDA. While US manufacturers have labeled products that contain heparin based on USP standards, the recent changes modified the reference standard for the drug's unit dose to match the World Health Organization's International Standard unit dose that is used in Europe. The revision reduces the potency of heparin by about 10% when compared with the previous USP standard.
Voelker R. New Standards Reduce Heparin Potency. JAMA. 2009;302(18):1956. doi:10.1001/jama.2009.1615