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Guide Health: Blood clotting — new alternatives to warfarin

Advances in anticoagulants offer people more treatment options

You probably take your blood’s ability to clot for granted. You cut your finger, and somehow the bleeding stops on its own!

However, if you have a disease or condition for which you need to prevent clotting, you may take an oral or injectable anticoagulant.

Atrial fibrillation is a type of irregular heart beat that allows your blood to pool and clot in your heart, which obviously is not good. It is estimated that one in four Canadians over 40 years of age has this heart beat irregularity, and many do not even know they are at risk.

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Deep vein thrombosis is a blood clot or thrombosis usually in the deep veins of your legs. If the clot detaches from the vein wall it is called an embolism and can travel throughout your body to lodge in your lungs, heart, or even brain.

On a long-haul flight (considered by the airline industry as any flight over two hours), sitting in a cramped seat for those hours may cause your blood to pool in your legs, and this in turn may lead to deep vein thrombosis or DVT.

A good preventive measure is wearing compression stockings to prevent the potential blood pooling. DVT can also occur after major surgery — especially knee or hip replacement surgery.

Joint replacement surgery is becoming more common with Can­ada’s aging population. In 2014 there were 8,500 of these surgeries, and forecasters predict we will continue to see increases of 20 per cent per year.

Regardless of why you need an anticoagulant, until recently warfarin was the one option that was commonly used. It is a vitamin K antagonist, and it works by depleting stores of this vitamin that your body needs to clot blood.

However, warfarin’s action is slow to start because you need to wait until the vitamin K is depleted.

As well, warfarin has many drug and food interactions, and the way your body handles warfarin depends upon your genetic makeup.

All these factors mean that doses of warfarin change depending upon lab results and vary from person to person. They also mean that with warfarin, regular monitoring is needed to ensure that its actions are within specific parameters. We need to be sure your blood does not clot too much, or not enough!

The newest group of anticoagulants are known as the direct acting oral anticoagulants or DOACs. They act directly on coagulation factors and thus are faster acting and have shorter durations of action.

DOACs also are more predictable in their actions and have fewer drug interactions. If you need to take an anticoagulant for an ongoing condition like atrial fibrillation, then you don’t need the regimen of lab work. And, even if you have joint replacement surgery, they are more convenient to use.

Three DOACs are available: apixaban, dabigatran, and rivaroxaban. Both apixaban and dabigatran need twice daily dosing, but rivaroxaban is only once a day with a recommendation for taking it with your evening meal.

DOACs should be avoided if you do not have good kidney function; there needs to be dose adjustment made for apixaban and dabigatran even if there is only moderate kidney function impairment.

All can cause too much bleeding, most often noticed as bruising, although by stopping the drug this can be quickly reversed. Both apixaban and rivaroxaban can be crushed if you can’t swallow tablets, but dabigatran needs to remain in its original package until you take it.

You often see television and magazine ads for new drugs, DOACs included, and you may wonder if they are as good as they sound. DOACs certainly won’t eliminate your need for an anticoagulant, but they are a good alternative to warfarin for some people.

About the author


Marie Berry is a lawyer/pharmacist interested in health and education.



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