Coumarin derivatives, such as warfarin and acenocoumarol, are the blood thinners of choice for the prevention and treatment of conditions in which blood clots can form in the veins and/or arteries (thromboembolism). With the development of NOACs (new oral anticoagulants), a new era appears to have arrived in 2015 for the prevention and treatment of thromboembolic complications.
What is a blood thinner?
A blood thinner, or anticoagulant, is a medication that prevents blood clotting. Roughly speaking, it takes longer for the blood to clot. The word blood thinner is therefore actually incorrect, because the blood is not diluted.
What are NOACs and what are they used for?
Anticoagulants such as acenocoumarol (Sintrom Mitis®) or warfarin play an important role in preventing strokes or TIAs in patients with atrial fibrillation. They are very effective, but blood tests and careful monitoring by the thrombosis service are necessary to prevent bleeding. In recent years, in addition to coumarin derivatives, new agents have come onto the market to influence blood clotting and which no longer require strict control. These are called the NOACs.
For the time being, NOACs can only be used in patients with nonvalvular atrial fibrillation, which means that the atrial fibrillation is not caused by valve defects in the heart. Furthermore, it can also be used to treat pulmonary embolism or a thrombosed leg.
What different types of NOACs are there?
Several manufacturers have been involved in the development of NOACs. The most important drugs in the Netherlands are rivaroxaban (Xarelto®), dabigatran (Pradaxa®) and apixaban (Eliquis®). They are most commonly prescribed for the prevention of cerebral infarctions in patients with atrial fibrillation.
How do they work?
NOACs inhibit part of the complex system involved in the formation of blood clots in the body. This means it takes longer for a blood clot to form and the risk of, for example, a cerebral infarction in patients with atrial fibrillation is reduced. The main difference with current anticoagulation such as acenocoumarol is that NOACs are less influenced by diet and that monitoring by the thrombosis service is no longer necessary.
Should every patient with atrial fibrillation change to a NOAC?
No, studies have shown that acenocoumarol (if properly monitored by the thrombosis service) is just as effective as a NOAC in preventing cerebral infarctions in patients with atrial fibrillation.
What are the possible side effects of a NOAC?
This varies per NOAC that is on the market. For example, dabigatran can cause stomach and/or intestinal problems. And like all other blood thinners, the most feared side effect is severe bleeding. However, research has shown that the risk of bleeding with a NOAC compared to warfarin is the same or even lower. A disadvantage is that there is no antidote on the market for a NOAC in 2015.
What happens if you forget to take a dose?
For a NOAC it is essential to take the prescribed dosage every day. This is because they work a lot shorter than, for example, acenocoumarol. If you have forgotten a dose, it is important to discuss what to do with the doctor or pharmacist who prescribed the drug. You can usually still take the forgotten dose.
Cost
The biggest obstacle is that NOACs are much more expensive than, for example, acenocoumarol. Furthermore, these are new drugs and doctors are not yet very familiar with the drugs and side effects. In the coming years, NOACs will become cheaper as they become more prescribed.
read more
- The history of anticoagulation (blood thinners)
