Important facts you need to know about Warfarin

What is Warfarin?
Warfarin is a drug used to reduce the risk of clotting. The natural antidote to Warfarin is Vitamin K, which is found in leafy green vegetables. It is safe to eat green vegetables, but you should try to maintain a steady quantity in your diet. Alcohol can be used safely in small quantities.

Warfarin is not a new drug, and has been used in patients for many years. Although it is the active ingredient in Ratsak, it is safe to use in people when prescribed in very measured doses.

When is Warfarin used?
Warfarin is used in patients who are at risk of forming blood clots that could lead to stroke, heart attack, or thrombosis in the legs or lungs. Warfarin is only prescribed with other anti-clotting drugs like aspirin in specific circumstances.

What are the side effects of Warfarin? Warfarin is safe when monitored closely by your doctor and has few major side effects.

• Risk of Bleeding: Warfarin does not cause bleeding, but it will make you bleed more freely if you cut or injure yourself. None-the-less, patients on Warfarin do have low but increased annual risk of major bleeding compared to people taking regular Aspirin (<1.0% vs 2.0%). Patients on Warfarin also have a slightly greater risk of intra-cranial bleeding when compared to people taking Aspirin (0.3% pa vs 0.1% pa). This risk is higher in the very elderly, and in people with a history of recent stroke and poorly controlled hypertension. Despite this, the risk of intracranial bleeding is substantially (>10x) lower than the risk of stroke due to other causes that Warfarin helps to prevent. Hence Warfarin has a clear net protective effect against stroke compared to Aspirin or other therapy in selected patients at risk of stroke.
  
  
• Other Risks : Very rarely (1:10,000) Warfarin has been associated with ulceration of the skin, which typically occurs within the first week of starting therapy. This is more common in people with a rare clotting disorder (Protein C deficiency).

How is Warfarin used?
Warfarin comes in variable size tables (typically 5, 2 and 1mg). You need to have each required to be on hand in case of a change in dose (eg: 6mg = 5mg + 1mg, 4mg = 2+2mg) Although the average maintenance dose of Warfarin is about 5mg/day, it may vary over time. Furthermore, the average dose varies widely (1mg – 15mg/day) between individuals. There are different formulations of Warfarin. They are all effective, but it is important that you always use the same formulation as their effect on the blood differs.

How is the effect of Warfarin Measured?
The effect of Warfarin is measured by a blood test called the INR

What is the INR?
The INR is an International Normalised Ratio of the anti-clotting effect on your blood. That is, it is an agreed international measure, which means that the results should be the same when checked anywhere in the world.

What should the INR be?
In a person not taking Warfarin the INR is 1.0, In your condition the INR should range between ______ &______

Levels <2.0 are not likely to be effective
Levels > 4.0 are unnecessarily high