By: LISA R. WILSON

The FDA has notified healthcare professionals that they are working with the makers of blood-thinner Plavix in order to determine the effectiveness of the drug in some patients.

The FDA is studying reports that taking certain heartburn medications mixed with clopidogrel (Plavix) decreases the benefits of the drug. Also, differences in effectiveness may be due to genetic differences in the way the body metabolizes clopidogrel.
Marketed by Bristol-Myers Squibb Co., Plavix is the second-best-selling drug in the world.

The drug manufacturers have agreed to a timeline for completing the studies. The FDA will review the new information and communicate its conclusions, as well as any recommendations, to the public at that time.

Until further information is available, the FDA recommends that patients should continue to take Plavix (clopidogrel) as directed, but healthcare providers should re-evaluate the need for prescribing starting treatment with Plavix. Also, patients taking Plavix should consult with their healthcare provider if they are currently taking or considering additional medication.

For more information, visit the FDA at http://www.fda.gov/medwAtch/safety/2009/safety09.htm.