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Indications - Warfarin is indicated in the following conditions- Prophylaxis and/or treatment of thromboembolic complications associated with atrial fibrillation and/or cardiac valve replacement Indicated to reduce the risk of death, recurrent myocardial infarction, and thromboembolic events such as stroke or systemic embolization after myocardial infarction Prophylaxis and treatment of venous thrombosis and pulmonary embolism Transient ischaemic attacks.

Dosage & Administration - Whenever possible, the baseline prothrombin time should be determined but the initial dose should not be delayed whilst awaiting the result. Use in adults: The usual adult induction dose of warfarin is 10 mg daily for 2 days. The subsequent maintenance dose depends upon the prothrombin time, reported as INR (international normalized ratio). The daily maintenance dose of warfarin is usually 3 to 9 mg (taken at the same time each day). The maintenance dose is omitted if the prothrombin time is excessively prolonged. Once the maintenance dose is established in the therapeutic range, it is rarely necessary to alter. In emergencies, anticoagulant therapy should be initiated with heparin and warfarin together. Where there is less urgency, as in patients disposed to or at special risk of thromboembolism, anticoagulant therapy may be initiated with warfarin alone. Control tests must be made at regular intervals and maintenance dosage further adjusted according to the results obtained. Use in children: Safety and efficacy in children <18 years old have not been established. However, there is evidence of use and the initial dose is usually 0.1 mg.kg-1.d-1 adjusted subsequently to aim for an INR range the same as in adults.

Side Effects - Hemorrhage is the principal adverse effect of oral anticoagulants. Other adverse reactions include nausea, vomiting, diarrhea, hypersensitivity, rash, alopecia, and unexplained drop in haematocrit, "purple toes", skin necrosis, jaundice, and hepatic dysfunction.

Contraindications - Warfarin can not be administered in the following cases; Actual or potential hemorrhagic conditions, eg. Peptic ulcer, or to patients with uncontrolled hypertension Severe hepatic or renal disease Pregnancy Known hypersensitivity to warfarin Bacterial endocarditis Its use within 24 hours following surgery or labor should be undertaken with caution, if at all.

Others - Pregnancy & Lactation Warfarin is contraindicated in the first trimester of pregnancy because of the risk of teratogenicity. It should not be used in women who are or may become pregnant because the drug passes through the placental barrier and may cause fatal hemorrhage to the fetus. Warfarin appears in the milk of nursing mothers in an inactive form. Infants nursed by mothers treated with Warfarin had no change in prothrombin times. Effects in premature infants have not been evaluated.