Blood Thinners and the Genetics Behind Drug Response

A study in the journal Lancet regarding a new blood thinning drug brings to mind the difficulty doctors and patients have in using anticoagulants to prevent clots that could otherwise lead to heart attacks or strokes.

The mostly commonly used blood thinner, warfarin (Coumadin®) has proven to be a godsend for millions of people at risk, but this study suggests that as many as half of those who use the drug do not benefit from it because of challenges related to finding the proper dose.

Calibrating the right prescription of warfarin is notoriously difficult because the right amount depends not just on such things as a person’s size, their diet and age, but also, importantly,their genes.

The new study isn’t about genetics. It’s by researchers at Duke Medical Center, who suggest that the new blood thinner apixaban is safer than warfarin and more effective at preventing strokes in people who have atrial fibrillation, a common heart rhythm disorder.

Apixaban hasn’t yet received FDA approval. That may soon change, but the study reminds us of all the challenges with current drugs and the tremendous amount of resources invested into finding drugs that are safe and effective for more people. Another complementary way to achieve that goal is by learning more about how individual patients may respond to specific drugs. Your genetics are a big part of that equation.

In the case of warfarin, aperson’s genetics directly impacts how sensitive they are to the drug. Although there are a number of factors that influence a person’s optimal dose of warfarin, genetic variations in the CYP2C9 and the VKORC1 genes play an important role in how the body responds to the drug. More than two years ago the FDA updated the labeling on warfarin to make note of this genetic influence but genetic testing is not required before prescribing warfarin.

Editor’s note: Pending an FDA decision, 23andMe no longer offers new customers access to health reports referred to in this post. Customers who purchased prior to November 22, 2013 will still be able to see their health reports, but those who purchased after that time will not. Those customers will have access to ancestry information as well as access to their uninterpreted raw data.

Related posts:
New Study Shows That Genetic Information Can Improve Administration Of Commonly Used Blood Thinner
A Prescription for Personalizing Medicine
23andMe Launches Its First NIH Funded Study
Health at 23andMe: When One Size Doesn’t Fit All






  • fbl

    Coumadin didn’t do what the Cardiologist wanted so they had me get some shots (don’t know of what) and they didn’t work. So they gave me the newest supposedly great alterntive-Xarelto.

    Not only did it not give the numbers they wanted, it has cause me some horrible side effects. My muscles are still suffering ten months later. Muscle wastage, weird traveling headaches etc. A long list of misery.

    The irony of the whole catastrophe is that my family Dr. said my blood flow is fine! He did some minor surgery a few months ago and asked if I was on blood thinners. I said no, that none of them worked. He said that the one test they use doesn’t tell the whole story and my blood is flowing well. I don’t need blood thinners!

    He asked if I was taking Nattokinase and I said yes. He said don’t worry about it then. I’m wondering why the tests didn’t work. Would the herb screw it up?

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