Antithrombin III
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This article is compiled based on the United States Pharmacopeia (USP) – 2025 Edition
Issued and maintained by the United States Pharmacopeial Convention (USP)
Antithrombin III human (heparin cofactor, factor II inhibitor, and factor X inhibitor) is a serine protease inhibitor. It is a glycoprotein having a molecular weight of 58,000 Da.
One Antithrombin III Unit is the amount found in 1 mL of normal human plasma. The potency of antithrombin III is not less than 4.0
Antithrombin III Units per mg of protein when tested in the presence of heparin. It exhibits 90% homogeneity when tested by SDS-PAGE.
Antithrombin III for test or assay purposes contains no detectable heparin. Test as follows. To a solution containing 1 Antithrombin III Unit per mL, add 1 μL of toluidine blue solution. In the presence of Heparin, the color changes from blue to purple.
