Putting Gene Tests to Use: More Than a Third of Patients Cannot Properly Metabolize Plavix®

FRANKLIN LAKES, N.J. and MONTREAL, Oct. 13, 2011 /PRNewswire/ -- A Medco Health Solutions, Inc. (NYSE: MHS) gene testing analysis found that 38 percent of patients prescribed Plavix® (clopidogrel)—an anti-platelet drug used to prevent blood clots, heart attack and stroke—were also using another drug that would impede its effectiveness.

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The analysis also showed that primary care physicians seem willing to incorporate gene testing into their clinical practice and are nearly 40 percent more likely to test for genetic mutations that affect drug metabolism than cardiologists when prescribing Plavix.

The analysis reviewed data from a genetic testing program offered to physicians by Medco, a leading pharmacy benefit manager. The test assesses genetic mutations that affect a patient's liver enzyme, called CYP2C19, which metabolizes many medications, including Plavix, the world's second best selling drug. Patients with genetic variations that reduce the effectiveness of  CYP2C19, or who use certain medications that block the enzyme so that it is unable to function properly, have been shown to have about a 50 percent increase in cardiovascular events while on Plavix.  Some of those medications include widely used heartburn drugs and antidepressants.

"Patients who cannot metabolize Plavix well due to certain genetic mutations in CYP2C19, or who are using CYP2C19 inhibitors, may be more likely to suffer adverse cardiovascular events, such as a heart attack or stroke, since the enzyme is necessary for the body to convert the drug to its active form," said Dr. Lon Castle, senior director, Department of Clinical Innovation at Medco and one of research authors.  "We also found that primary care physicians and neurologists seemed to be more accepting of the use of gene testing."

The analysis also indicated that messages discussing genetic variations and potential drug interactions resulted in 31 percent of doctors making a prescription change shortly after receiving test results.  Preventing drug interactions is as important as testing for genetic variations in drug metabolism in helping doctors ensure the medications they select work most effectively—which can play a role in helping lower healthcare costs.

For example, about 70 percent of patients do not have the CYP2C19 genetic variations that reduce the effectiveness of Plavix, meaning they would be candidates to use a less expensive generic medication when the drug loses patent protection later this year.  However, in order to increase the likelihood that the drug is metabolized effectively, physicians would have to avoid prescribing other medications which inhibit the activity of the CYP2C19 enzyme.

"The combination of drug utilization review and genetic testing gives doctors another tool to make decisions and improve the safety and outcomes for their patients," said Dr. Donald Pittman, the national practice leader for cardiovascular health in the Medco Therapeutic Resource Centers®.  "Genetic testing allows doctors to maximize the cardiovascular benefit and drug and drug utilization review minimizes the risk from drugs that may interfere with the metabolism of Plavix."

Over a third using 2C19 inhibitors

The 100-patient analysis found that 1 percent of the patients could be regarded as "poor metabolizers" (two reduced-function gene components), 29 percent were "intermediate", 37 percent were "extensive" (two normal functioning gene components) and 33 percent were "ultrarapid" metabolizers of CYP2C19.   The research also found that 38 percent of the patients were using drugs that were "2C19 inhibitors"–such as proton pump inhibitors (PPIs) to treat heartburn or certain antidepressants–that interfere with how Plavix is processed in the body.  Recent studies have shown that patients using a 2C19 inhibitor with Plavix have a heightened risk for a cardiovascular event.

Of the patients in the analysis, about 25 percent were using proton pump inhibitors, six percent were using antidepressants, and another seven percent were using both categories of medications.  After the genetic test results were reported to physicians, 38 percent of the patients also on a proton pump inhibitor had a therapy change.  No changes were made for those patients on an antidepressant therapy.

While testing was offered most frequently to cardiologists (47 percent) and primary care physicians (33.5 percent) during the period analyzed, which took place from December 2010 through April 2011, neurologists had the highest acceptance rate of the gene testing for their patients using Plavix (52.6 percent), followed by primary care physicians (41.2 percent) and cardiologists (29.7 percent).

"Genetic testing is gaining some traction in clinical practice, but it takes time before innovations are consistently incorporated into practice," Castle said.  "There will come a time when doctors routinely send a cheek swab to a lab to make sure the right patient gets the right drug."

Analysts from Medco presented the results in Montreal at the 12th International Congress of Human Genetics and the 61st Annual Meeting of The American Society of Human Genetics.

Medco has pioneered the use of genetic testing in pharmacy care to find where patient outcomes can be improved by either matching patients to more effective treatments or helping them avoid adverse drug events.  The Medco Research Institute®, the pharmacy benefit manager's research arm, is conducting a head-to-head genetic testing study of Plavix versus Effient®, a newer anti-platelet drug.

About Medco

Medco Health Solutions, Inc. (NYSE: MHS) is pioneering the world's most advanced pharmacy® and its clinical research and innovations are part of Medco making medicine smarter™ for approximately 65 million members.

With more than 20,000 employees worldwide dedicated to improving patient health and reducing costs for a wide range of public and private sector clients, and 2010 revenues of nearly $66 billion, Medco ranks 35th on the Fortune 500 list and is named among the world's most innovative, most admired and most trustworthy companies.

For more information, go to http://www.medcohealth.com.

This press release contains "forward-looking statements" as that term is defined in the Private Securities Litigation Reform Act of 1995. These statements involve risks and uncertainties that may cause results to differ materially from those set forth in the statements. No forward-looking statement can be guaranteed, and actual results may differ materially from those projected. We undertake no obligation to publicly update any forward-looking statement, whether as a result of new information, future events, or otherwise. Forward-looking statements in this press release should be evaluated together with the risks and uncertainties that affect our business, particularly those mentioned in the Risk Factors section of the Company's Annual Report on Form 10-K and Quarterly Reports on Form 10-Q filed with the Securities and Exchange Commission.

SOURCE Medco Health Solutions, Inc.