Though the confusion over the interference of the two classes of drugs reigns supreme since long, the results of the recent studies conducted by Sanofi-Aventis and Bristol-Myers Squibb (the manufacturer of clopidogrel) clearly pronounce against the mixing of the two.
"The results of those studies are to avoid the combination of those two medications" Mary Ross Southworth, deputy director for safety with the U.S. Food and Drug Administration's Division of Cardiovascular and Renal Products said.
Furthermore, the side-effects are such grave that the combination should be ‘avoided even if the two drugs are taken hours apart’, she marked.
The interference
Heart patients who undergo stent surgeries are often prescribed Plavix for its anti-clotting properties. Plavix prevents the blood from getting too sticky and forming clots, which can set off another heart attack, medics explain.
But because Plavix can upset the stomach, causing gastric
problems, heartburn or even bleeding, it is often backed by antacids known as proton pump inhibitors (PPI) to conteract these symptoms.
In response, the key ingredient in the PPI medications blocks an enzyme the body needs to break down Plavix, cutting the drug's health effects to nearly half.
"The PPI drug blocks the conversion of clopidogrel to its active state, so it can't have the anticlotting activity it is supposed to. You're taking Plavix, but it's not having the anticlotting activity it should’ Dr. Christopher Cannon, a cardiologist at Brigham and Women’s Hospital in Boston explained.
However, heart patients who require taking acid-lowering drugs should switch to taking drugs from the H-2 blocker family (Johnson & Johnson's Mylanta and Boehringer Ingelheim's Zantac). Bestowing the same antacid properties, these drugs do not interfere with Plavix's anti-blood clotting action.
Other drugs under scanner:
According to the FDA, other drugs that may also interfere with Plavix, rendering it less effective include: cimetidine (Tagamet), fluconazole (Diflucan), etravirine, felbamate (Felbatol), fluoxetine (Prozac), fluvoxamine (Luvox), ketoconazole (Nizoral), ticlopidine (Ticlid) and voriconazole (Vfend).
Plavix is the second-best selling drug in the world with global sales amounting to $8.6 billion in a year. On the other hand, proton pump inhibitors are the most commonly prescribed drugs in the world.
The results were presented Monday at the American Heart Association's annual meeting in Orlando, Florida.
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