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Back to Coumarin derivatives

Warfarin sodium

Coumadin, Panwarfin, Sofarin

Pregnancy Category D

Drug classes

Coumarin derivative

Mechanism of action

Interferes with the hepatic synthesis of vitamin K-dependent clotting factors (factors II-prothrombin, VII, IX, and X), resulting in their eventual depletion and prolongation of clotting times.


  1. Venous thrombosis and its extension, treatment, and prophylaxis
  2. Treatment of atrial fibrillation with embolization
  3. Pulmonary embolism, treatment, and prophylaxis
  4. Prophylaxis of systemic emobization after acute MI

Unlabeld uses:

  1. Prevention of recurrent transient ischemic attacks
  2. Prevention of recurrent myocardial infarction
  3. Adjunct to therapy in small-cell carcinoma of the lung


  1. Allergy to warfarin or tartrazine (contained in the 7.5-mg tablet marketed as Panwarfin);
  2. SBE
  3. Hemorrhagic disorders
  4. Tuberculosis
  5. Hepatic diseases
  6. GI ulcers
  7. Renal disease
  8. Indwelling catheters
  9. Spinal puncture
  10. Aneurysm
  11. Diabetes
  12. Visceral carcinoma
  13. Uncontrolled hypertension
  14. Severe trauma (including recent or contemplated CNS, eye surgery; recent placement of IUD)
  15. Threatened abortion
  16. Menometrorrhagia
  17. Pregnancy (known to cause fetal damage and death)
  18. Lactation (suggest using heparin if anticoagulation is required)

Use caution in the presence of CHF, diarrhea, fever; thyrotoxicosis;
senile, psychotic, or depressed patients.

Adverse effects

  • GI: Nausea, vomiting, anorexia, abdominal cramping, diarrhea, retroperitoneal hematoma, hepatitis, jaundice, mouth ulcers
  • Hematologic: Granulocytosis, leukopenia, eosinophilia
  • GU: Priapism, nephropathy, red-orange urine
  • Dermatologic: Alopecia, urticaria, dermatitis
  • Bleeding: Hemorrhage; GI or urinary tract bleeding (hematuria, dark stools; paralytic ileus, intestinal obstruction from hemorrhage into GI tract); petechiae and purpura, bleeding from mucous membranes; hemorrhagic infarction, vasculitis, skin necrosis of female breast; adrenal hemorrhage and resultant adrenal insufficiency; compressive neuropathy secondary to hemorrhage near a nerve
  • Other: Fever, "purple toes" syndrome

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