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FDA to Take A Closer Look at Plavix

Jan 27, 2009 | Parker Waichman Alonso LLP

The U.S. Food and Drug Administration (FDA) will be working with the maker’s of the anti-stroke medication Plavix to enable a better understanding of the drug and its effects on the body, especially when taken with another class of drugs, said MedWatch.  The LA Times reports that Plavix is the world's second-best selling drug and had global sales of $7.3 billion in 2007.

A prior study found that patients taking the clot reducer Plavix (Generic: Clopidogrel bisulfate) experienced more than 12 times as many ulcers as those patients who were treated with aspirin plus a heartburn pill.  It is believed that up to half of those patients who are now taking Plavix do so because their doctors assume that Plavix is safer on the stomach than aspirin, said that study's lead author, Dr. Francis K. L. Chan.  Of note, the American College of Cardiology and the American Heart Association recommends Plavix therapy instead of aspirin therapy for those heart and stroke patients at risk of developing ulcers.

The study also suggested that the drug’s guidelines should be changed, and that many of those patients taking Plavix should consider switching to aspirin plus a heartburn pill, Dr. Chan said.  Dr. Chan’s study looked at 320 patients whose ulcers had healed.  He treated half with Plavix and half with aspirin plus Nexium, a heartburn pill. Thirteen of the patients taking Plavix, or 8.6 percent, experienced renewed ulcer bleeding during the year; just one patient, or 0.7 percent, of those taking aspirin and Nexium developed an ulcer bleed.

The FDA advised healthcare professionals this week that it ordered the makers of Plavix—Bristol-Myers Squibb/Sanofi Pharmaceuticals Partnership—to collaborate with the agency on studies that are hoped to reveal deeper information on the possible effects of genetic factors, said MedWatch and on possible drug interactions, said the LA Times.  In particular, the study will be looking at the effect of PPIs—proton pump inhibitors—on Plavix, since it is unclear which, either, or both of these factors are involved, reported MedWatch.  PPIs, which are taken for the treatment of acid reflux, are described by the LA Times as medications which suppress stomach acid production.  Nexium, Prevacid, Aciphex, and Protonix are some examples of prescription PPIs and Prilosec OTC is an over-the-counter PPI.

Medwatch confirmed that the FDA knows of reports which indicate that clopidogrel efficacy is uneven, with results differing in some patients over others.  The FDA expects that it could take several months to conduct the studies.  MedWatch urged healthcare providers to re-evaluate the need to start or continue PPIs in those patients being treated with clopidogrel; likewise, patients taking the combination or considering the combination are advised to speak to their healthcare providers, and to bear in mind that Prilosec OTC can be taken without a prescription.

The LA Times reported that the FDA move came about because of reports that clopidogrel’s cholesterol reducing efficacy seemed to be compromised in some patients.  The FDA also noted that genetic factors might be involved and other drugs could also affect how the drug is metabolized in the body, said the LA Times.  PPIs seem to reduce the breakdown of some drugs by the liver and may increase the concentration of diazepam (Valium), phenytoin (Dilantin), and warfarin (Coumadin), said the LA Times.