Generic
Warfarin Sodium
8 brands available in the market
At a glance
Warfarin Sodium is an oral anticoagulant which helps prevent the formation of harmful blood clots in the legs, lungs, brain and heart. It is used for deep vein thrombosis, pulmonary embolism and stroke prevention.
Description
Warfarin is a vitamin K antagonist which acts to inhibit the production of vitamin K by vitamin K epoxide reductase. The reduced form of vitamin K, vitamin KH2 is a cofactor used in the γ-carboxylation of coagulation factors VII, IX, X, and thrombin.
Indications
- Deep vein thrombosis
- Pulmonary embolism
- Stroke prevention
- Prophylaxis and/or treatment of thromboembolic complications associated with atrial fibrillation and/or cardiac valve replacement
- Reduce the risk of death, recurrent myocardial infarction, and thromboembolic events after myocardial infarction
- Transient ischaemic attacks
Therapeutic class
Anti-coagulants, Oral Anti-coagulants
Pharmacological class
Anticoagulant
Pharmacology
Warfarin inhibits synthesis of vit K-dependent coagulation factors VII, IX, X and II and anticoagulant protein C and its cofactor protein S. No effects on established thrombus but further extension of the clot can be prevented.
Mechanism of action
Inhibits synthesis of vitamin K-dependent coagulation factors, preventing blood clot formation.
Dosage
Adult Dose (Oral):
- Initial: 2-5 mg once daily for 2 days, or 10 mg daily for 2 days in healthy individuals
- Initiate warfarin on day 1 or 2 of LMWH or unfractionated heparin therapy and overlap until desired INR
- Check INR after 2 days and adjust dose according to results
- Usual maintenance dose: 2-10 mg daily
- Elderly: Initial <5 mg once daily; maintenance 2-5 mg once daily
- Hepatic impairment: Severe: Avoid
Administration
- May be taken with or without food
- Swallow tablets whole; do not chew, crush or break
- Take at a fixed time each day
- Avoid Vitamin K rich food such as spinach, collards, broccoli, spring onions, cucumber and dried basil
Missed dose
If you miss a dose, skip it and continue with your normal schedule; do not double the dose.
Side effects
Common Side Effects:
- Hemorrhage (principal adverse effect)
- Jaundice
- Hepatic dysfunction
- Vasculitis
- Pancreatitis
- Nausea
- Vomiting
- Diarrhoea
- Taste perversion
- Abdominal pain
- Flatulence
- Rash
- Purpura
- Pruritus
- Alopecia
- Fever
- Chills
Precautions & warnings
- Does not usually affect ability to drive
- Avoid making sudden major changes to your diet during treatment
- Do not consume alcohol; may increase side effects
- Consult doctor before surgery or dental treatment
- Do not discontinue use without consulting your doctor
Contraindications
- Patient with haemorrhagic tendencies or blood dyscrasias
- Recent or contemplated surgery of the CNS or eye
- Overt bleeding or active ulceration involving the GI, genitourinary or resp tract
- Cerebrovascular haemorrhage
- Cerebral aneurysms
- Dissecting aorta
- Pericarditis and pericardial effusions
- Bacterial endocarditis
- Threatened abortion
- Eclampsia, pre-eclampsia
- Malignant HTN
- Pregnancy
Drug interactions
- Ticlopidine: cholestatic hepatitis may occur
- Other anticoagulants, antiplatelet agents, NSAIDs, serotonin reuptake inhibitors: increased risk of bleeding
- CYP2C9, CYP1A2 and CYP3A4 inhibitors: increased INR
- CYP2C9, CYP1A2 and CYP3A4 inducers: decreased INR
- Fibrinolytic drugs (streptokinase, alteplase): increased risk of bleeding (potentially fatal)
Food interactions
It is unsafe to consume alcohol with Warfarin Sodium.
Use in pregnancy
Use in Pregnancy: Highly unsafe; do not use during pregnancy.
Pregnancy Category: X — always consult a doctor before taking during pregnancy.
Use in lactation
Use in Lactation: Safe; human studies suggest the drug does not pass into breastmilk in significant amount and is not harmful to the baby.
Pediatric use
Safety and efficacy not established in children (initial dose may be 0.1 mg/kg/day)
Geriatric use
Lower doses required to produce therapeutic level of anticoagulation in elderly
Renal / hepatic impairment
Renal Impairment: Safe; no dose adjustment recommended; regular blood tests recommended
Hepatic Impairment: Caution needed; dose adjustment may be needed; severe: avoid
Overdose effects
Symptoms: Hemorrhage or a potential bleeding state.
Treatment: Temporary withdrawal of warfarin; if necessary, infusion of fresh-frozen plasma or whole blood; Vitamin K, 5 mg to 10 mg orally or intravenously.
Storage conditions
Do not store above 30°C. Keep away from light and out of the reach of children.