(Updates with FDA comments in fourth paragraph.)
Dec. 6 (Bloomberg) -- U.S. regulators pushed for more studies on birth control pills containing the hormone drospirenone, such as Bayer AG’s Yaz, after concluding the risk of blood clots is unclear.
An FDA advisory panel will meet Dec. 8 to review studies that have found conflicting evidence of the chances of clots associated with the oral contraceptives, according to a Food and Drug Administration staff report released today. The panel will also weigh the risks and benefits of the pills.
The FDA published a report in October that found birth control pills containing drospirenone are linked to a higher danger of blood clots relative to standard low-dose versions. Six trials have shown conflicting data on whether the products are linked to a higher risk, the agency said at the time.
“None of the studies to date provides a definitive answer,” FDA said in the report today. “The entire body of studies provides conflicting evidence that cannot easily be reconciled by consideration of any single difference among studies.”
Women taking drospirenone were 74 percent more likely to experience clots than those on low-estrogen pills, the agency said. Drospirenone is similar to the natural female hormone progesterone. Bayer conducted studies that found no increased blood-clot risk.
Bayer’s Yaz and Yasmin brought in $1.5 billion in sales for the German drugmaker last year as its second best-selling drug, less than the $1.8 billion in 2009. Teva Pharmaceutical Industries Ltd. launched a generic version of Yaz in May 2010.
The advisory panel will also evaluate Dec. 9 the risk of blood clots associated with Johnson & Johnson’s Ortho Evra birth control patch. The FDA isn’t required to follow the panel’s recommendations.
--Editors: Chris Staiti, Bruce Rule
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