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ANTICOAGULANTS

What are the types of Anticoagulant?

Warfarin (Marevan) is the main one, which is given by mouth. Heparin is given by injection, either under the skin or through a drip into a vein. Its brand names include Alphaparin, Fragmin, Clexane and Innohep.

What are Anticoagulants for ?

Anticoagulants make the blood less likely to clot. They are given once a clot has formed, to stop it from extending any further. Such a clot could otherwise become bigger, or could break loose, travel down an artery and lodge in another part of the body. In the brain this could cause a stroke; in the heart it could cause a heart attack; in the leg it could cause gangrene. Clots may also form in the veins of the leg and pelvis. If they break loose, they can lodge eventually in the lung; a pulmonary embolism. Anticoagulants can also be used by people at risk of developing blood clots, such as those with certain inherited disorders which predispose to clotting, or after injury or surgery (particularly bone, joint or heart operations). They are often given after a heart attack or stroke or to people with an irregular heartbeat.

How do Anticoagulants work ?

They stop or slow down the process of blood clotting in a number of ways. Heparin works almost immediately, while warfarin takes 2 to 3 days to take full effect.

How should Anticoagulants be used ?

Their use may be urgent: a high level of blood thinning may be required. Then heparin will be given to you through a drip into a vein while in hospital. Blood tests are checked every 1 to 2 days to check dose levels. Particularly to prevent clots while you are in hospital, heparin may be given to you as a simple injection once or twice daily: again blood tests may be done to check the dose. Warfarin is used for longer term treatment, often for months or even years. It may follow on a short course of heparin. The dose of warfarin needed is different for everyone. The dose may need to be changed quite often, too. This happens with certain changes in your diet, if you need to take other medicines or if you become ill for another reason. A test, usually called an INR, is done by the doctor from time to time, to check and adjust your warfarin dose. You should make sure that the correct dose is written down on a card, and that you know exactly the date for your next blood test. Do try to take your dose at about the same time each day. Do not change or stop your treatment yourself: you might risk either the forming of a new blood clot, or on the other hand bleeding. Those decisions must be taken by discussion with your doctor.

During Treatment with Anticoagulants

You should not notice any change in your health. Bruising, dark bowel motions, bleeding nose or gums may mean too big a dose of warfarin: contact your doctor or anticoagulant clinic straight away. Again, do not change your dose yourself. If you miss a dose, take it when you remember. If it is nearly time for your next dose, take it, but miss the following dose. If you miss several doses, tell your doctor.

Drug Interference

A number of painkillers, particularly aspirin and so called non-steroidal anti-inflammation tablets, increase the blood thinning effect and could make you bleed. Check with your doctor or pharmacist before you take any painkiller to be sure that it is safe. Paracetamol, however, is a safe painkiller. Some antidepressants, some drugs used for treatment of stomach ulcers and some heart pills can also increase the blood thinning effect: your doctor should check these for you. Some antibiotics also increase the effect, and your doctor will be careful to choose a safe one for you if you get an infection. Modest amounts of alcohol may be consumed while taking warfarin. However larger amounts and the presence of liver damage will increase the activity of Warfarin and could cause bleeding. The "fibrate" group of drugs used to lower blood fat levels increase the blood thinning effect too. Your doctor would probably halve your dose of anticoagulant if you were to be started on any of this group. Some drugs reduce the blood thinning effect. The most important of these are anti-epileptic drugs and barbiturates, and some antifungal drugs and antacids. New interactions are being discovered: between you, your doctor and your pharmacist, you must always make sure that any additional drug is safe for you. If you are having heparin injections, you will probably have very little pain but some bruising where you inject. This is unsightly, but nothing to worry about unless it becomes painful or spreads more than a couple of inches (5 cm) from where you have injected.

What if Anticoagulants are not taken ?

You would seriously risk developing a clot either in a vein or artery. Courses of anticoagulant treatment may range from a few months to years, depending on the condition being treated. In all cases, do not stop you tablets unless your doctor has directly advised it.

General advice on the use of Anticoagulants

Warfarin can harm you baby if taken in the first 3 months of pregnancy. If you are pregnant or think you might be, it is essential that you tell your doctor before you start anticoagulants. If you want to become pregnant while taking warfarin, tell your doctor first. You can be transferred to heparin injections. These are not harmful to a baby, and can be readily given by yourself. If you need an operation or dental treatment, you must tell your surgeon or dentist because of the risk of bleeding. They will arrange to change the doses, if necessary. Always carry your anticoagulant card (or better still a bracelet or pendant if you are on long-term treatment).

In a bad accident, those treating you would not otherwise know that you were on blood thinning tablets. The effect of bleeding under such circumstances can be quickly reduced by giving you an injection of vitamin K. This reverses the effect of warfarin. Warfarin can also increase the risk of bleeding from a peptic ulcer, so let your doctor know if you get very bad indigestion or are known to have an ulcer. It can also increase the bleeding from cuts or bruises which you may get: you bleed for a little longer and may require a bit of pressure on the bleeding area for 10 minutes or so. Let your doctor know if you are in any way concerned. If you have any questions not answered by this leaflet, please talk about them with your doctor or pharmacist. Keep this leaflet handy in case you wish to refer to it again.