FDA warns against concomitant use of Plavix, certain heartburn drugs.

Moral of the story: If you are taking these two drugs (blood thinners and proton-pump inhibitors for heartburn) talk to your doctor. You need to up the dosage of the blood thinner.

Source: AMA Morning Rounds 11/18/09

FDA warns against concomitant use of Plavix, certain heartburn drugs.

NBC Nightly News (11/17, story 2, 0:40, Williams) reported that "millions of Americans take" Plavix (clopidogrel) "to reduce the risk of heart attacks and strokes." But, because the blood thinner "can upset the stomach, it is often prescribed alongside drugs like Prilosec (omeprazole) and Nexium (esomeprazole)." Now, however, the FDA is warning that those popular medications can "weaken the effect of Plavix."

In fact, the "anti-clotting benefits of Plavix are cut almost in half when taken with over-the-counter or prescription Prilosec, according to a notice posted today on the Food and Drug Administration's website," Bloomberg News (11/18, Larkin) reports. Thus, the "agency ordered Paris-based Sanofi and New York-based Bristol-Myers to update the prescribing information for Plavix and study the potential for other drug interactions." Although the "Plavix prescribing information was updated in January to discourage use with Prilosec," the latest warning includes the those two PPIs and nine other "similar drugs."

However, the agency "did not have enough information to say whether other drugs in the same class as Nexium and Prilosec...also react adversely with Plavix," the Los Angeles Times (11/18, Zajac) reports. "This includes such drugs as Prevacid [lansoprazole] and Protonix [pantoprazole]."

Nevertheless, those who still "need to reduce their acid should take drugs from the H-2 blocker family, which include Johnson & Johnson's Mylanta [aluminum hydroxide/magnesium hydroxide/simethicone] and Boehringer Ingelheim's Zantac [ranitidine]," the AP (11/18, Perrone) reports. "FDA scientists say there is no evidence those drugs interfere with Plavix's blood clotting." As for the omeprazole, the FDA decided to strengthen its warning after reviewing "a 150-patient study submitted by Sanofi over the summer."

That report indicated that drugs like Nexium reduce the production of an enzyme -- CYP 2C19 -- that sets Plavix in motion, according to the Wall Street Journal (11/18, Mundy). Several other drugs, WebMD (11/17, DeNoon) reported, "also inhibit CYP 2C19, and the FDA says patients on Plavix should avoid them as" well: Tagamet (cimetidine), Luvox (fluvoxamine), Ticlid (ticlopidine), Diflucan (fluconazole), Nizoral (ketoconazole), VFEND (voriconazole), Intelence (etravirine), Felbatol (felbamate), and Prozac, Serafem, and Symbyax (fluoxetine).

HealthDay (11/17, Reinberg), Dow Jones Newswire (11/17, Favole), and CQ HealthBeat (11/18) also covered the story