Precautions and warnings

Regular testing of prothrombin time (PT) and international normalized ratio (INR), or another suitable blood clotting test, is very important for patients taking anticoagulants like warfarin. Many things can affect how these medicines work, such as traveling, changes in diet, changes in health, new or stopped medications, or even environmental changes. It is especially important to check PT/INR more often right after a patient leaves the hospital, or if there are changes in their other medications.

Some factors can make warfarin work too strongly, meaning the dose may need to be reduced. These include losing weight, being elderly, having acute illnesses, kidney problems, eating less vitamin K, or taking certain other medications. On the other hand, the dose of warfarin may need to be increased if the patient gains weight, has diarrhea or vomiting, eats more vitamin K, fats, or oils, or starts taking certain drugs.

If a patient switches from one brand or type of warfarin to another, extra blood tests are necessary. If warfarin needs to be reversed, vitamin K can be used, but it takes several days to work. In an emergency, fresh frozen plasma should be given to quickly reverse the effects of warfarin.

Drug Interactions

Taking ticlopidine at the same time can cause cholestatic hepatitis. The risk of bleeding increases if you use this medicine with other blood thinners (like argatroban, dabigatran, or heparin), antiplatelet drugs (such as aspirin, cilostazol, or clopidogrel), NSAIDs (including celecoxib, diclofenac, or ibuprofen), or certain antidepressants called serotonin reuptake inhibitors (such as citalopram, paroxetine, or venlafaxine). Some drugs that block liver enzymes (like amiodarone, capecitabine, or ciprofloxacin) can increase your INR, raising the risk of bleeding. In contrast, drugs that make these enzymes work faster (enzyme inducers) can lower your INR, making the blood clot more easily.

**Warning: Using fibrinolytic drugs (like streptokinase or alteplase) together with this medicine can greatly increase the risk of serious, potentially fatal bleeding.**

Contraindications

1. Conditions that cause bleeding or could lead to bleeding, such as peptic ulcers, or in patients with uncontrolled high blood pressure.
2. Severe liver or kidney disease.
3. During pregnancy.
4. If you are allergic to warfarin.
5. In cases of bacterial endocarditis.

Warfarin should also be used very carefully, if at all, within 24 hours after surgery or childbirth.

Mode of actions

Warfarin works by blocking the production of vitamin K-dependent clotting factors—specifically factors VII, IX, X, and II—as well as the anticoagulant proteins C and S. While warfarin does not dissolve blood clots that are already present, it does prevent them from getting bigger. This also helps reduce the risk of new clots breaking off and causing blockages elsewhere in the body.

Dosage & Administration

Oral
Treatment and prophylaxis of venous thromboembolism
Adult: Initially, 5 mg daily. Rapid anti-coagulation: Initially, 10 mg daily for 2 days. Adjust subsequent doses based on PT/INR. Usual maintenance dose: 2-10 mg daily.
Elderly: Lower initial dose.
Hepatic impairment: Severe: Avoid.

Pregnancy & Lactation

This medicine must not be used during pregnancy. It can be absorbed through the skin and lungs caused can damage your unborn child’s organs and cause congenital disabilities. Strict two effective types of birth control starting one month before and during treatment and for three years after stopping this medicine. Discuss with your doctors if you are not sure which types of birth control are effective for you. You must need to take pregnancy tests regularly during your treatment with this medicine and for at least three years after taking this medicine. If it seems that you do become pregnant stop taking this medicine and call your doctor immediately. If you really become pregnant, miss a menstrual period, or have sex without using two forms of birth control. In some cases, your doctor can prescribe emergency contraception to prevent pregnancy. People on this medicine should not donate blood during the treatment and for three years afterward.

This medicine is also contraindicated breast milk. Breastfeeding is not recommended while using this medication and for three years afterward.

Pack Size & Price