Warfarin Sodium is the sodium salt of warfarin and is an important pharmaceutical active pharmaceutical ingredient (API) belonging to the coumarin anticoagulant class. It acts as a vitamin K antagonist and interferes with the vitamin K cycle required for the production of several vitamin K-dependent coagulation factors. Warfarin Sodium is therefore used in pharmaceutical formulations designed to reduce blood coagulation and prevent thrombus formation.
Warfarin Sodium is chemically defined as sodium 2-oxo-3-[(1RS)-3-oxo-1-phenylbutyl]-2H-1-benzopyran-4-olate. The substance has the molecular formula C19H15NaO4 and a molecular weight of approximately 330.31 g/mol. The CAS Number commonly assigned to Warfarin Sodium is 129-06-6.
Warfarin Sodium is a sodium salt derived from warfarin, a 4-hydroxycoumarin derivative. The active molecule contains a coumarin ring system substituted with a 3-oxo-1-phenylbutyl group. Warfarin itself is a racemic compound containing R- and S-enantiomers, while the pharmaceutical Warfarin Sodium substance is generally described as the racemic sodium salt.
The BP 2025 monograph describes Warfarin Sodium as a white or almost white, hygroscopic, amorphous powder. It is very soluble in water and ethanol, soluble in acetone and very slightly soluble in methylene chloride.
Warfarin Sodium produces its anticoagulant effect by interfering with the vitamin K cycle. It inhibits vitamin K epoxide reductase, reducing the regeneration of the active reduced form of vitamin K.
Reduced vitamin K is required for the gamma-carboxylation and maturation of several vitamin K-dependent coagulation proteins. Inhibition of this process decreases the functional production of coagulation factors II, VII, IX and X, as well as the anticoagulant proteins C and S.
The resulting reduction in functional coagulation-factor activity produces the anticoagulant effect associated with Warfarin Sodium.
Warfarin Sodium is a hygroscopic pharmaceutical substance and can be affected by environmental moisture. It is also sensitive to light and should therefore be appropriately protected during storage and handling.
The BP 2025 monograph specifies storage in an airtight container protected from light. The International Pharmacopoeia also notes that Warfarin Sodium can gradually degrade when exposed to humid conditions, with degradation becoming faster at higher temperatures.
Warfarin Sodium has considerably greater aqueous solubility than the free Warfarin compound because of its sodium salt form.
According to the BP 2025 description, Warfarin Sodium is very soluble in water and ethanol (96%), soluble in acetone and very slightly soluble in methylene chloride.
This solubility profile is an important consideration during formulation development, analytical sample preparation and pharmaceutical manufacturing.
Warfarin Sodium is manufactured through chemical synthesis involving the formation of the Warfarin structure followed by conversion to the sodium salt. The manufacturing process requires control of starting materials, reaction conditions, intermediates, purification and final salt formation.
Because Warfarin Sodium is hygroscopic and can exist in different physical forms, control of moisture, solid-state characteristics and storage conditions is important during API manufacturing.
The final API is subjected to appropriate analytical testing to establish identity, assay, related substances, water content, pH, residual solvents and other applicable quality attributes.
Quality control of Warfarin Sodium includes several pharmacopoeial tests. The BP 2025 monograph specifies infrared identification together with identification of propan-2-ol and sodium. Related substances are determined by liquid chromatography.
The assay is specified at 98.0–102.0% on an anhydrous basis. The monograph also specifies pH, water content, related substances, phenolic ketones and propan-2-ol.
The BP 2025 monograph specifically identifies 4-hydroxycoumarin (impurity B) and benzalacetone (impurity C) as specified impurities.
Each of these impurities is limited to NMT 0.15%. Other unspecified impurities are limited to NMT 0.10% each, while total impurities are limited to NMT 0.30%. The disregard limit is 0.05%.
These limits are important quality attributes for Warfarin Sodium API and provide chromatographic control over process-related and degradation-related substances.
The BP 2025 specification gives a pH range of 7.6–8.6 for the specified aqueous solution. Water content is controlled at NMT 4.0%.
The difference between the BP 2025 specification and older International Pharmacopoeia information should be noted. The International Pharmacopoeia gives pH 7.2–8.3 and water NMT 4.5%, while the BP 2025 monograph gives the more current BP values of 7.6–8.6 and NMT 4.0%.
Warfarin Sodium is used as an anticoagulant active pharmaceutical ingredient. It is associated with pharmaceutical formulations used for prevention and treatment of thromboembolic conditions where anticoagulant therapy is indicated.
The API is relevant to pharmaceutical tablet and oral dosage-form development and manufacturing. Warfarin Sodium is also used in analytical research, formulation development and pharmaceutical quality-control applications.
Warfarin Sodium can be characterized using several analytical techniques. Infrared spectroscopy is used for identification, while liquid chromatography is used for related-substance determination.
UV-visible spectrophotometry is used in the pharmacopoeial assay procedure. The BP 2025 assay procedure determines Warfarin Sodium content spectrophotometrically at 308 nm, using a specified specific absorbance value.
Additional testing can include water determination, pH measurement, residual-solvent testing and evaluation of physical characteristics.
Warfarin Sodium should be stored in an airtight container and protected from light. Because the substance is hygroscopic, protection from excessive environmental moisture is important.
Appropriate packaging and controlled storage conditions help maintain the chemical and physical quality of the API throughout its intended storage period.
Swapnroop Drugs & Pharmaceuticals provides pharmaceutical API solutions for pharmaceutical development and manufacturing requirements. Warfarin Sodium is an established anticoagulant API with well-defined pharmacopoeial quality attributes.
For pharmaceutical applications, Warfarin Sodium can be evaluated according to applicable pharmacopoeial requirements, customer specifications and regulatory requirements. Consistent control of assay, impurities, water content, pH and physical characteristics is important for maintaining API quality.
| Parameter | Specification |
|---|---|
| Appearance | white to off-white crystalline powder |
| Identification | IR & HPLC compliant |
| Assay (HPLC) | 98.0% – 102.0% |
| pH (1% Solution) | 7.6–8.6 |
| Individual Impurity | NMT 0.15% |
| Total Impurities | NMT 0.30% |
| Water Content | NMT 4.0% |
| Melting Point | About 161–162°C |