What is it about ?
Coagulation is a mechanism that allows blood clots to form when blood comes into contact with air or if the blood vessels are damaged. In the event of an injury, the clot causes the bleeding to stop. Unfortunately, a blood clot can also form in the circulatory system and either block a blood vessel where it forms (thrombosis, for example in the leg) or form in the heart (for example in case of fibrillation. ear), get carried into the bloodstream and block a blood vessel elsewhere in the body (embolism). This can cause, for example, a heart attack (infarction), a cerebrovascular accident (CVA), or a pulmonary embolism.
Basically, the body has two systems to clot blood. The first, the platelet system, allows rapid clotting; platelets stick to each other, we speak of platelet aggregation. The clot thus formed is not really solid. To become stronger, it needs protein. These coagulation proteins called ‘coagulation factors’ constitute the second system. The proteins form a network, which firmly binds the clot.
To decrease the tendency to coagulate, we can act on each of these two systems. It is sometimes said that we “thin” the blood, but this is not quite correct. This is because the treatment does not make the blood more liquid, but it prevents the blood clotting mechanisms. It is therefore more correct to speak of anticoagulation and anticoagulants.
In practice, anticoagulation involves two types of drugs: antiplatelet agents and anticoagulants.
Antiplatelet agents
These drugs prevent platelets from sticking together, which slows the formation of blood clots.
Anti coagulants
These drugs slow down the activity of coagulation proteins. There are two main classes of products on the Belgian market. They intervene at different stages of the production of coagulation proteins:
- Vitamin K antagonists, also called coumarin anticoagulants. In Belgium, vitamin K antagonists are
- Acenocoumarol under the Sintrom® brand
- Phenprocoumone under the Marcoumar® brand
- Warfarin under the brand Marevan®
- Direct oral anticoagulants. In Belgium, direct oral anticoagulants are
- Apixaban under the brand Eliquis®
- Dabigatran under the Pradaxa® brand
- Edoxaban under the brand Lixiana®
- Rivaroxaban under the Xarelto® brand
For more information on antiplatelet drugs and vitamin K antagonists, we recommend that you read the ‘Anticoagulants’ guide.
Among the elements that differentiate vitamin K antagonists from direct oral anticoagulants, we find, for example, in addition to their different modes of action, the following:
- There is an antidote if taking a vitamin K antagonist results in a high risk of bleeding or bleeding: vitamin K. For some direct oral anticoagulants, there are currently no products that neutralize the action if there is bleeding, which can be a problem if there is bleeding.
- The effect of vitamin K antagonists should be checked regularly with blood tests. While, for oral anticoagulants, the variations in blood concentrations are less important; they therefore require fewer controls. At the same time, this is also a disadvantage because the doctor does not know precisely how well the treatment is suitable for the person, and is therefore less able to assess the risk of bleeding.
When to use direct oral anticoagulants (DOA)?
Anticoagulants are especially indicated in cases of cardiovascular disease with an increased risk of blood clots forming. It is prescribed in case of:
- atrial fibrillation of the heart: an arrhythmia that causes the atria to contract quickly and irregularly;
- prevention and treatment of deep vein thrombosis (DVT): a blood clot in one of the deep veins, usually in the leg;
- prevention and treatment of blood clots in the lungs (pulmonary embolism);
- prevention of deep vein thrombosis (DVT) in people operated on for a hip or knee prosthesis.
Who cannot use direct oral anticoagulants (DOACs)?
- people with mechanical heart valves;
- people who suddenly become seriously ill because they are at a higher risk of bleeding;
- children;
- pregnant or breastfeeding women;
- people with liver disease and whose kidneys are not working well.
What are the side effects of direct oral anticoagulants (DOACs)?
Bleeding is the main side effect of DOACs. The risk increases if the patient’s kidneys work less well and if they take certain medicines (see below). The risk of bleeding is estimated based on:
- blood pressure;
- kidney or liver disease;
- history of stroke;
- history of heavy bleeding;
- of age;
- taking medication and consuming alcohol.
Some people have gastrointestinal symptoms.
What should you watch out for when taking direct oral anticoagulants (DOACs)?
It is important to take the DOA strictly according to the schedule set up by the doctor. Indeed, a DOA does not circulate for long in the body and therefore quickly loses its effect. If you regularly forget to take it, clots may form.
Once to four times a year, the doctor will perform a detailed physical examination and blood test, depending on the condition for which he has prescribed the DOAC for you.
One of the main side effects of DOACs is bleeding. Avoid combining a DOA with other drugs that increase the risk of bleeding, except prior consultation with the doctor on this matter. The main drugs to avoid are:
- non-steroidal anti-inflammatory drugs;
- certain antidepressants;
- tramadol;
- other medicines which act on the formation of clots (antiaggregants and anticoagulants).
The doctor will give you some advice about other possible products.
Other factors that increase the risk of bleeding include:
- anemia;
- a high age (> 75 years);
- active cancer;
- untreated high blood pressure;
- hepatic cirrhosis (a kind of scarring of the liver);
- varicose veins in the esophagus;
- bleeding in the past;
- a simultaneous decrease in the amount of platelets;
If you are taking a DOA and you have severe bleeding, contact a doctor immediately. Depending on the severity of the bleeding, your general practitioner will refer you to an emergency department. In the event of very severe bleeding, the DOAC should be stopped. Regarding dabigatran (Pradaxa®), there is a medicine that neutralizes the effect of this medicine.
If you are planning to have the operation, you must first tell the surgeon and general practitioner that you are taking a DOAC. Depending on the procedure, you may need to stop the DOA and temporarily take another type of anticoagulant (in injections).
Want to know more?
- Antiaggregants – CBIP – Belgian Center for Pharmacotherapeutic Information
- Oral anticoagulants – CBIP – Belgian Center for Pharmacotherapeutic Information
- Direct oral anticoagulants – CBIP – Belgian Center for Pharmacotherapeutic Information
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