Warfarin sodium(including isopropanol)

Appearance: White to off white crystalline powder

Organic Impurities：4-Hydroxycoumarin≤0.3%；Benzalacetone≤0.3%；Alice’s ketone≤0.3%；Any individual unspecified impurity≤0.10%；Total impurities≤1.0%

Isopropyl Alcohol Content (crystalline clathrate form)：8.0%–8.5%

pH：7.2–8.3

Water：NMT 0.3% for the crystalline clathrate form

ASSAY（USP）：97.0%–102.0% on the anhydrous basis for the amorphous form or on the anhydrous and isopropyl alcohol-free basis for the crystalline form.

Mechanism of action
Warfarin is a derivative of coumarin, with a chemical structure of 3- (a-phenylacetone) -4-hydroxycoumarin. There is no anticoagulant effect inside the test tube, that is, it does not participate in in in vitro anticoagulation. It mainly inhibits the synthesis of vitamin K-dependent coagulation factors II, VII, IX, and X in liver microparticles, but the effect occurs slowly, with the maximum effect occurring within 3-5 days. Vitamin K can promote the carboxylation of amino terminal glutamic acid of vitamin K-dependent coagulation factors II, VII, IX, and X into gamma carboxyglutamic acid. Carboxylation can promote the binding of vitamin K-dependent coagulation factors to phospholipid surfaces, thus accelerating blood clotting. Gamma carboxylation requires the participation of reduced vitamin K (vitamin KH2). Dicoumarin inhibits the activity of vitamin K epoxide reductase, thereby blocking the production of vitamin KH2 and inhibiting the gamma carboxylation of vitamin K-dependent coagulation factors. In addition, vitamin K antagonists can inhibit the carboxylation of anticoagulant proteins C and S.