Factsheet ajg warfarin

They are not quite interchangeable and caution is required in prescribing by the doctor and dispensing by the pharmacist. Both drugs come as 1 mg and 5 mg tablets, but Coumadin is also Warfarin: an anticoagulant or
available as a 2 mg tablet, while Marevan is “blood thinner”
Blood tests
The widely used drug Warfarin is often referred to Samples of blood are required for laboratory testing as a “blood thinner”. It does not thin the blood; it every couple of days when the drug is first stops blood from clotting. It is not like a paint introduced. We al vary in our response to the drug thinner or liquid paper thinner. It is a drug which (as determined by PT or INR values). When the blocks specific processes within the body, required level is achieved, tests may initial y be on interfering with the availability of Vitamin K. It is a weekly basis for the first month or so, and then therefore referred to as a Vitamin K antagonist. Vitamin K is essential for the proper formation of blood clots. An under-dose of Warfarin wil not stop Long term regular testing is needed for several blood from clotting. Taken in overdose, bleeding reasons. There may be interactions with other may occur at any susceptible site in the body. drugs introduced for some different purpose. Background
complementary therapies: the effects of Warfarin Fifty years ago, a famous London cardiologist (with are increased by ginger, garlic and ginseng. Other the voice of a Welsh preacher) giving a medical herbal treatments may also interfere with the lecture in the USA, startled his audience, opening effectiveness of the drug. PT and INR are also his address thus- “Anticoagulants?- rat poison!” influenced by Vitamin K intake in certain foods. A Warfarin in large dose (for rats and mice) is indeed list of foods which may interfere with the effects of a highly effective rodent poison. The rodents bleed Warfarin may be available with the tablets, or from the pharmacist, or prescribing doctor. Most people achieve the desired level of PT or INR and maintain How is Warfarin taken?
it with a steady dose thereafter, provided that they Human administration needs to be adjusted to have regular habits, control ed alcohol consumption ensure that the level of effect lies in a range (alcohol increases the anticoagulant effect of between where the dose is effective and where it should not lead to unwanted bleeding. Laboratory tests give us the measure of effectiveness in an Who is prescribed Warfarin?
individual patient on a specific day. The measure is Some people need an anticoagulant on a long term cal ed the prothrombin time (PT) or is converted to or permanent basis. This long term medication is the International Normalised Ratio (INR). The usual for people who are likely to develop blood normal INR is 1. The therapeutic range of INR is usual y 2 to 3. Warfarin is taken in tablet form. In Australia, there are two major preparations, The drug is commonly used in those who have the pulse irregularity of atrial fibril ation, those with The views expressed are those of the author and not necessarily those of the Heart Research Centre established chronic heart failure who are breathless and the risk of subsequent stroke or other crises and have enlarged heart chambers, those with owing to a portion of blood clot coming free and valve abnormalities and an enlarged heart and lodging in the brain or elsewhere. Ful y monitored those who have artificial heart valves (prostheses) and properly control ed, the gains for the many far replacing previously damaged, narrowed or leaking outweigh the possible hazards for the few. Is this heart valves. Al of these conditions are much more another balancing act? No, this is good preventive common amongst the elderly, a rapidly increasing medicine and patient care. Like al medications, portion of the population. Thus medication with Warfarin should be prescribed, dispensed, Warfarin is also increasing rapidly. Does that matter? Yes, it does. The older one is, the more likely the blood vessels are to be damaged easily, such that bleeding may occur anywhere. Bleeding may be into the stomach if there is an ulcer, into the urine if there is a kidney stone, into the bowel or into the brain causing a stroke if the blood pressure is high. Thus we have increasing risk of For more information go to our website
bleeding with advancing age, increasing risk of www.heartresearchcentre.org
blood clotting with advancing age, increasing sensitivity to drugs including Warfarin with advancing age and increasing chance of drug interactions with advancing age as we take more medications for other conditions related to ageing. This seems to present a dilemma, a medical balancing act. It is not too bad. Blood tests reveal any trends in PT or INR to be changing (one way or the other). If the PT and INR is too low, the Warfarin dose is increased. If the PT or INR is too high, the Warfarin dose can be reduced: also there Some people require Warfarin for a period of only weeks or months. These include those with deep vein thrombosis (DVT) in the legs or elsewhere and people who have had a blood clot move from the Is Warfarin effective and truly valuable?
In the face of al of the above, does Warfarin treatment have overriding benefit? The answer is yes, it does. Ful y control ed, the drug markedly reduces the formation of blood clots in the heart The views expressed are those of the author and not necessarily those of the Heart Research Centre

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