What is Anticoagulant Therapy: Medication, Pathologies, Ways of Administration and Monitoring

Anticoagulant medication is used to slow the process of blood clotting.

Either used to prevent a blood clot or prevent the growth of those that have already formed. The most common anticoagulant medication is Warfarin.

The most common pathologies by which anticoagulant medication is prescribed are:

Deep vein thrombosis occurs when a blood clot forms in one of the large veins in the leg or arm.

Pulmonary embolism: This is a blood clot that forms in, or travels to, the lungs.

Atrial fibrillation: this term refers to an irregular heart rhythm. This happens when the atria do not contract simultaneously. This means that blood does not flow through them as quickly as it should, and blood is more likely to clot. If a clot is expelled, it can travel to the brain and cause a stroke. It can also travel to other parts of the body. The probability of stroke in patients with atrial fibrillation is approximately five times greater than that of the general population.

Warfarin can reduce the risk of stroke by 60 to 70 percent.

Mechanical heart valves: If you have an automatic heart valve, long-term anticoagulation therapy will be needed to prevent blood clots in the valve.

Many people with congenital heart defects need to take anticoagulants. Common reasons why this treatment includes heart valve replacement, heart rhythm disorders, or complicated previous surgeries such as the Fontan operation. Anticoagulant drugs slow blood clotting, prevent complications such as blood clots on artificial valves and valve obstruction, and avoid blood clots from traveling to the brain and causing a stroke.


Anticoagulants are usually administered orally. In some cases, they are administered through the vein (intravenously) or by injections just under the skin (subcutaneous).

Ways to administer anticoagulants

Oral medications

These include mainly aspirin or clopidogrel (Plavix) and Warfarin (Coumadin). These medications decrease coagulation tendency by interfering with platelets or blocking the body’s production from that of coagulation substances.

Aspirin tends to cause fewer bleeding complications than clopidogrel or Warfarin, but it can not sufficiently block coagulation. It also causes an upset stomach.

Clopidogrel does not require regular blood tests but affects platelet function and bleeding, sometimes up to 7 – 10 days. It is necessary to avoid elective operations and dental work while taking aspirin or clopidogrel due to bleeding risks.

Warfarin increases the risk of severe bleeding problems, even when the dose is at the recommended level.

Carefully and regularly, the level of anticoagulants requires control and monitoring. If you take Warfarin, you will need to limit some physical activities to reduce the risk of injury, particularly head injuries.

Warfarin during pregnancy can also cause malformations in a baby, so you should discuss the risks with your doctor before becoming pregnant. It would help if you avoided aspirin when treated with Warfarin.

If you have a mechanical heart valve, low doses of aspirin can be added to Warfarin to help prevent the formation of blood clots.

Intravenous medications

Intravenous heparin acts quickly to thin the blood. When it stops, the effect also disappears quickly. Oral anticoagulants are long-acting, so these medications should be discontinued if you need surgery (including dental surgery).

Subcutaneous medications

There are two anticoagulant medications: heparin and low molecular weight heparin (Lovenox). Both can be injected just under the skin (subcutaneous). These are used when more time is required (for example, during pregnancy) and eliminate the need for a long-term intravenous line.

Monitoring of medicines

If you are taking Warfarin, your doctor will regularly check the blood-clotting level to correct the dose. The dose of Warfarin will be carefully adjusted to maintain an appropriate level of coagulation. The medication must be taken exactly as prescribed.

Anticoagulation in pregnancy

Women who require anticoagulation and become pregnant need to take special precautions. Warfarin may have a significant risk to the fetus, especially in the first trimester.

Many women who take warfarin switch to heparin during the first weeks of pregnancy. Some may then stay with heparin during pregnancy. Others can be started with Warfarin during the middle of pregnancy.