Save on this medicine
Other brands with the same active ingredient
These brands contain the same active ingredient (Warfarin Sodium). Same strength and form. Confirm the switch with your doctor or pharmacist.
Indications & Uses
G Warfarin is indicated for:
Pharmacology
Warfarin works by blocking vitamin K, a vitamin the body needs to make several clotting proteins. It does this by inhibiting vitamin K epoxide reductase, the enzyme that recycles vitamin K. Once the enzyme is blocked, the body cannot turn vitamin K back into its active form.
The active form, vitamin KH2, acts as a cofactor in the γ-carboxylation of coagulation factors VII, IX, X and thrombin. This carboxylation changes the shape of the factors so they can bind Ca2+ and attach to phospholipid surfaces. Factors VII, IX, X and thrombin that have not been carboxylated are biologically inactive, which is how they interrupt the coagulation cascade. Proteins C and S, the body's own anticoagulant proteins, also need γ-carboxylation to work. This matters most for thrombin, which must be activated before it can form a thrombus.
During the γ-carboxylation reaction, which is catalyzed by γ-glutamyl carboxylase, vitamin KH2 is converted to vitamin K epoxide. Vitamin K epoxide is then changed to vitamin K1 by vitamin K epoxide reductase, and vitamin K1 goes back to vitamin KH2 through vitamin K reductase. Warfarin binds to vitamin K epoxide reductase complex subunit 1 and inhibits the enzyme irreversibly. This stops the recycling of vitamin K, because vitamin K epoxide can no longer be converted to vitamin K1.
At first, this creates a short period in which the blood is more likely to clot. Proteins C and S break down first, with half-lives of 8 and 24 hours, and factor VII follows with a half-life of 6 hours. Factors IX, X and finally thrombin break down later, with half-lives of 24, 36 and 50 hours. It is this later drop that produces the main anticoagulant effect.
To reverse the anticoagulation, vitamin K has to be supplied, either from outside the body or by removing the blockage on vitamin K epoxide reductase. Then the body needs time to make new coagulation factors. In the liver, this takes about 2 days.
Vitamin K2 is functionally the same as vitamin K1, but it is made by bacteria in the gut. This is why antibiotics can affect it, since killing these bacteria can lower the body's vitamin K2.
Dosage Reference
Reference Information Only
Dosages shown are general references from official sources. Always consult your doctor or pharmacist for personalized dosing.
Adults:
If possible, check the baseline prothrombin time before starting warfarin sodium. But don't hold back the first dose while you wait for the result.
Use in adults: The usual adult induction dose of warfarin is 10 mg daily for 2 days. After that, the maintenance dose depends on the prothrombin time, which is reported as the INR (international normalized ratio). The daily maintenance dose is usually 3 to 9 mg, taken at the same time each day. If the prothrombin time is excessively prolonged, the maintenance dose is omitted. Once a maintenance dose has been settled within the therapeutic range, it rarely needs to be changed.
In emergencies, anticoagulant therapy should be started with heparin and warfarin together. Where there is less urgency, as in patients disposed to thromboembolism or at special risk of it, therapy may be started with warfarin alone. Control tests must be done at regular intervals, and the maintenance dose adjusted further according to the results.
Use in children: Safety and efficacy in children under 18 years old have not been established. There is evidence of use, though, and the initial dose is usually 0.1 mg.kg-1.d-1. It is then adjusted to aim for the same INR range as in adults.
Side Effects
The most serious side effect of warfarin is bleeding. Other side effects can include nausea, vomiting, diarrhoea, allergic reactions, rash and hair loss. Some people may notice an unexplained drop in haematocrit, "purple toes", skin necrosis, jaundice or problems with the liver.
Cautions & Contraindications
Warnings & Precautions
Periodic checks of prothrombin time (PT) or international normalized ratio (INR), or another suitable coagulation test, are essential. Many factors, alone or together, including travel, dietary changes, environment, physical condition and medication, can influence how a patient responds to anticoagulants. It is generally good practice to check the patient's response with an additional PT/INR test soon after hospital discharge, and whenever other medications are started, stopped or taken irregularly. The following factors may increase the effects of warfarin and call for a lower dose: weight loss, older age, acute illness, poor kidney function, reduced dietary vitamin K intake, and use of certain other drugs (see drug interactions). Factors that may call for a higher maintenance dose include weight gain, diarrhea and vomiting, increased intake of vitamin K, fats and oils, and use of certain other drugs. Careful additional laboratory monitoring is needed if a patient switches from one formulation to another. Reversing warfarin's anticoagulant effect with vitamin K takes several days; in emergencies, fresh frozen plasma should be given instead.
Contraindications
Warfarin must not be given in the following situations: actual or potential hemorrhagic conditions (for example, peptic ulcer), or uncontrolled hypertension; severe hepatic or renal disease; pregnancy; known hypersensitivity to warfarin; and bacterial endocarditis. It should be used within 24 hours of surgery or labor only with caution, if at all.
Pregnancy & Breastfeeding
PREGNANCY & BREASTFEEDING
Warfarin must not be used during the first trimester of pregnancy, as it carries a risk of birth defects (teratogenicity). More broadly, it should be avoided in women who are pregnant or who may become pregnant, since the drug crosses the placenta and can cause fatal bleeding in the fetus.
In breastfeeding, warfarin passes into breast milk, but only in an inactive form. Studies of infants breastfed by mothers taking warfarin have shown no change in their prothrombin time. However, its effects on premature infants have not been studied.
⚠️ Talk to your doctor before taking any medicine during pregnancy or while breastfeeding.
Overdose
If bleeding occurs, or there is a chance it may start, the clotting activity has been pushed down too far. This can be corrected by stopping warfarin for a time. If needed, fresh-frozen plasma or whole blood is given by infusion as well. Vitamin K, 5 mg to 10 mg by mouth or into a vein, may also be required to support the specific treatment with co-factor concentrates.
⚠️ In an emergency call 999 or go to the nearest hospital emergency department.
Storage
Store Warfarin Sodium at a temperature no higher than 30°C. Keep it away from light, and make sure children can't reach it.
Drug Interactions
Common questions about G Warfarin 5 mg
What is G Warfarin 5 mg Tablet?
G Warfarin 5 mg Tablet is a medicine that contains Warfarin Sodium. It is made by Gonoshasthaya Pharmaceuticals Ltd. It belongs to the Anti-coagulants group of medicines.
What is G Warfarin used for?
G Warfarin is used for: Cardiac Arrhythmia, Myocardial Infarction, Deep Vein Thrombosis, Stroke.
What are the side effects of G Warfarin?
The most serious side effect of warfarin is bleeding. Other side effects can include nausea, vomiting, diarrhoea, allergic reactions, rash and hair loss.
Can I take G Warfarin during pregnancy or while breastfeeding?
PREGNANCY & BREASTFEEDING Warfarin must not be used during the first trimester of pregnancy, as it carries a risk of birth defects (teratogenicity). More broadly, it should be avoided in women who are pregnant or who may become pregnant, since the drug crosses the placenta and can cause fatal bleeding in the fetus. Talk to your doctor before taking any medicine during pregnancy or while breastfeeding.
What happens if I take too much G Warfarin?
If bleeding occurs, or there is a chance it may start, the clotting activity has been pushed down too far. This can be corrected by stopping warfarin for a time. In an emergency call 999 or go to the nearest hospital emergency department.
How should I store G Warfarin?
Store Warfarin Sodium at a temperature no higher than 30°C. Keep it away from light, and make sure children can't reach it.
Can I take other medicines with G Warfarin?
Some medicines can interact with Warfarin Sodium, for example: Clopidogrel Bisulphate, Levofloxacin Hemihydrate, Naproxen Sodium, Paroxetine Hydrochloride, Diclofenac Sodium + Misoprostol, Metronidazole + Miconazole Nitrate. Tell your doctor or pharmacist about every medicine you take.
Do I need a prescription for G Warfarin?
G Warfarin is a prescription (Rx) medicine. Take it as your doctor advises.