* Prilosec, Nexium cut Plavix effectiveness by nearly half
* FDA: Plavix label to highlight interaction risk
* Warning follows data from new Sanofi-Aventis study
(Recasts first sentence, adds details on new study, comment
from FDA official)
By Ben Hirschler
WASHINGTON, Nov 17 Common heartburn pills
Prilosec and Nexium cut the blood-thinning effect of
Sanofi-Aventis SA's (SASY.PA) and Bristol-Myers Squibb Co's
(BMY.N) heart drug Plavix, U.S. officials warned on Tuesday.
The stomach drugs inhibit a key enzyme and reduce by almost
half the anti-clotting effect of Plavix, which is taken by
millions of people to reduce the risk of heart attacks and
stroke, the Food and Drug Administration said.
Plavix is the world's second-biggest-selling medicine, with
global sales of around $9 billion.
The U.S. label for Plavix, known also as clopidogrel, is
now being updated with new warnings on the use of AstraZeneca
Plc's (AZN.L) Prilosec and other similar drugs, including
Nexium, the agency said.
Plavix is widely used with such so-called proton pump
inhibitors, or PPIs, to reduce stomach acid and avoid gastric
Prilosec is available generically as omeprazole and is also
sold over-the-counter (OTC) by Procter & Gamble Co (PG.N).
The medicine used to be AstraZeneca's top-selling product
but has now been overtaken by the company's newer product,
Nexium, which sold $5.2 billion in 2008.
Mary Ross Southworth, deputy director for safety in the
FDA's division of cardiovascular and renal products, said the
problem of interaction between such drugs and Plavix had been
highlighted in a new 150-patient study conducted by Sanofi.
Results of that study were presented to the FDA over the
"We think that the mechanism of action is because of
omeprazole's activity on the 2C19 enzyme," Southworth told
That enzyme is important because it is needed to break down
Plavix into its active form in the body. If the action of the
enzyme is restricted, less-active Plavix is available in the
The FDA said patients who needed a medicine for stomach
acid should take antacid tablets or alternative older drugs
like ranitidine and famotidine -- available on prescription or
OTC -- but not cimetidine.
Worries about mixing Plavix and PPIs are not new, but
experts have continued to debate the pros and cons of combining
An analysis presented at the European Society of Cardiology
annual meeting in Barcelona in August appeared to offer
reassurance by finding that PPIs did not interfere with the
clinical benefits of either Plavix or Eli Lilly (LLY.N) and
Daiichi Sankyo's (4568.T) new drug Effient. [ID:nLV266191]
Southworth, however, said this sub-analysis from a larger
clinical trial had significant limitations, since patients were
not randomized in terms of PPI use.
(Reporting by Ben Hirschler, editing by Gerald E. McCormick,
Tim Dobbyn and Matthew Lewis)