Warfarin Sodium

Generic Details

Generic Name

Warfarin Sodium

Other Names

  • Coumadin
  • Jantoven

Drug Class

  • Anticoagulant

Chemical Formula

C19H15NaO4

Molecular Weight

330.308 g/mol

Mechanism of Action

  • Inhibits the enzyme Vitamin K epoxide reductase complex subunit 1 (VKORC1)

Indications

  • Prophylaxis and treatment of venous thrombosis and pulmonary embolism
  • Atrial fibrillation with embolization
  • Prophylaxis and treatment of thromboembolic complications associated with cardiac valve replacement and atrial fibrillation
  • Reduction of risk of death, recurrent myocardial infarction, and thromboembolic events such as stroke or systemic embolization after myocardial infarction

Common Dosage Forms

  • Tablet: 1mg, 2mg, 2.5mg, 3mg, 4mg, 5mg, 6mg, 7.5mg, 10mg

Typical Dosage

  • 2 to 10mg orally once a day, individualized based on INR results

Pediatric Dosage

  • Safety and effectiveness in pediatric patients have not been established

Geriatric Dosage

  • Initial dose is usually lower in the elderly due to increased susceptibility to bleeding

Side Effects

  • Bleeding (major or minor)
  • Hematoma
  • Nausea
  • Vomiting
  • Abdominal pain
  • Diarrhea
  • Hypersensitivity reactions

Contraindications

  • Hypersensitivity to warfarin
  • Active bleeding
  • Recent or potential injury
  • Severe uncontrolled hypertension
  • Pregnancy (unless indicated)

Pregnancy Category

  • D - Evidence of risk

Lactation Safety

  • Probably safe, excreted into breast milk but considered low risk for the infant

Drug Interactions

  • Many drug interactions due to its metabolism pathway via cytochrome P450 enzymes

Overdose Symptoms

  • Bleeding (internal or external)
  • Hematuria
  • Melena
  • Ecchymoses

Antidote for Overdose

  • Vitamin K
  • Fresh frozen plasma (FFP)

Storage Conditions

  • Store at room temperature away from moisture and heat

Pharmacokinetics

  • Absorption: Rapidly and completely absorbed after oral administration
  • Distribution: Highly bound to plasma proteins
  • Metabolism: Extensively metabolized in the liver
  • Excretion: Primarily excreted in the urine, also via feces

Precautions

  • Regular monitoring of International Normalized Ratio (INR)
  • Avoid sudden changes in diet or alcohol consumption
  • Caution in patients with hepatic or renal impairment

Warnings

  • Increased risk of bleeding, especially in the elderly
  • Interaction with many medications
  • Regular monitoring required to maintain INR within the therapeutic range

Others

  • Lifestyle changes such as complying with dietary restrictions and avoiding activities that may lead to injury are important while on warfarin therapy.