WSJ BLOG/Health: Basic Science: To Respond to Plavix, Don't Forget to Take It
05/29/2012| 10:01am US/Eastern
(This story has been posted on The Wall Street Journal Online's Health Blog at http://blogs.wsj.com/health.)
By Ron Winslow
For patients with advanced heart disease, an increasingly important question in the 21 century clinic is: What is your CYP2C19 status?
That's not a secret password to your bank account -- it's the name of a gene that affects how people respond to the blockbuster blood thinner Plavix. About 30% of us have a variation in the gene that limits the drug's ability to turn off activated platelets in our blood vessels and prevent them from forming clots that can cause a heart attack.
The drug, which accounted for $6.62 billion in U.S. sales for Bristol-Myers Squibb and Sanofi last year ($7.09 billion world-wide, if you're counting), went off patent earlier this month. As the Heart Beat column in today's WSJ reports, the availability of much cheaper versions of Plavix is intensifying a debate over how useful CYP2C19 and other measures are in guiding treatment decisions for heart patients.
One issue is how Eli Lilly's Effient and AstraZeneca's Brilinta -- expensive rival brand-name treatments -- will fare in the face of cheaper competition from generic Plavix, which is known as clopidogrel. Even before the patent expiration, when the price playing field was essentially level, neither drug got any traction against Plavix despite studies showing then superior to the market leader -- and despite their not being significantly affected by the CYP2C19 gene.
But some doctors believe the attention being paid to genetics masks a more important reason patients don't respond to the drug: compliance.
"Despite all of this about [genetic] non-responders, probably the No. 1 reason why people don't respond to their medicine is that they don't take it," Gregory Dehmer, director of cardiology at Scott & White Hospital, Temple, Texas, tells the Health Blog.
While specific numbers for Plavix aren't available, studies indicate that 50% of heart patients stop taking important medications within a year of their initial prescription.
Generic clopidogrel "is good for patients" because it could help improve the situation by making the drug more affordable, Dehmer says.
But even that isn't likely to solve the compliance problem. Express Scripts, the big pharmacy benefit manager, has looked at reasons why people stop taking drugs. Steve Miller, the company's chief medical officer, tells the Blog that affordability accounts for 15% of lack of adherence. Side effects or other clinical reasons explain another 15%. Most of the time, Miller says, people just forget.
Efforts to "crack the code" for the role of CYP2C19 in Plavix response are an important endeavor, he says. Meantime, though, fresh efforts to remind people of the importance of adherence may lead to better results.
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