In parts of the body where blood tends to flow slowly, e.g. in veins, near heart valves (natural or artificial) or in heart chambers which do contract normally, blood clots can easily form.
A small piece can break off and be carried in the circulation where it blocks an artery, thereby starving a part of the body of oxygen. If that part happens to be the brain, then a stroke occurs; a clot blocking the artery to the lungs is called a lung embolus, which can be fatal.
Warfarin is a drug used to prevent blood clots forming in certain people who are high risk of clot formation, eg. those with established vein thrombosis, abnormal heart valves, artificial heart valves or atrial fibrillation (a heart rhythm disorder – see details below). Warfarin acts by preventing Vitamin K from making the proteins needed for blood clotting. Vit. K is also involved in the process of mineralising bone, and Warfarin also interferes with this function, which can result in osteopaenia. Warfarin and Vit K thus oppose each other, so changing blood levels of the one will have an effect on the other.
YOU NEED TO KNOW…
When used and monitored correctly, Warfarin can be lifesaving. It can, however be difficult to control because so many factors influence its metabolism. Because of this problem, (see below) the most common side effect experienced is that of excessive bleeding, which can occur anywhere in the body e.g. in the gut.
Warfarin tablets must be stored at room temperature, away from light and humidity – your bathroom or kitchen is therefore not a good place to store this medicine.
Ingesting foods containing high amounts of Vit K will decrease the effectiveness of Warfarin, e.g. leafy green vegetables, liver, broccoli, brussel sprouts, asparagus, cabbages, lettuces, peas, avocados and some vegetable oils. Some natural products in high doses can also affect warfarin activity e.g. ginko, ginseng, goji berries, cranberry, green tea, chondroitin with glucosamine.
Blood levels of Warfarin must be monitored regularly (with an INR test) to remain effective. If levels are too high, internal bleeding can result. Very low levels can lead to abnormal clot formation.
Besides the clotting proteins which Vit.K helps to make, your body has another clotting system to prevent bleeding in blood with faster flow (arteries): this other system relies on tiny cells in your blood called platelets. Aspirin and anti-inflammatories prevent platelets from doing their job. Taking aspirin or anti-inflammatories together with Warfarin will therefore inactivate BOTH your clotting mechanisms, and the risk of dangerous haemorrhage becomes extremely high. Anti-inflammatories are often found in pain medications – if you are on Warfarin PLEASE ASK YOUR DOCTOR which pain or fever medications are safe to use.
Antibiotics can reduce the number of bacteria in the gut which make your Vit. K (which is a natural opponent of Warfarin). Less gut Vit. K means that your usual dose of Warfarin may now be too much for you and bleeding can result. Remember to check your INR if you have been prescribed antibiotics.
If your thyroid gland is underactive, you will be less responsive to Warfarin. Your dosage will thus have to be monitored and adjusted when you are on thyroid medication.
A MedicAlert disc is essential for anyone on Warfarin. Ask your doctor for application forms or contact medicAlert directly on 086-111-2979 or buy on line at www.medicalert.co.za/shop/