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(Updates to add stock price in eighth paragraph.)
Dec. 9 (Bloomberg) -- Bayer AG’s Yaz and its class of birth control pills containing the hormone drospirenone were backed in a close vote of U.S. advisers seeking clearer guidance for women about the danger of potential blood clots.
Studies have shown conflicting evidence about whether women who take the pills have a higher risk of blood clots than if they take older birth control pills that don’t contain drospirenone. Those ambiguous results prompted the U.S. Food and Drug Administration to request yesterday’s review.
The reproductive and drug safety advisory panels voted 15-11 that the benefits of the class of oral contraceptives including Yaz outweigh the risks. The advisers also voted 21-5 that information labels for the pills be changed to better reflect the potential for blood clots. The FDA isn’t required to follow the panels’ advice.
“All of these studies have significant strengths and weaknesses,” said Julia Johnson, acting chairwoman of the panel and chair of the University of Massachusetts Medical School Department of Obstetrics and Gynecology.
Panel members were concerned the results may have been affected by factors that weren’t studied such as women’s body mass index, smoking habits, family history and ethnicity, Johnson said.
Difficult to Assess
“I think this makes it very difficult for us to determine any magnitude of increased risk, if there is any increased risk,” said Paula Hillard, a panel member and chief of the Division of Gynecologic Specialties at Stanford University School of Medicine near Palo Alto, California.
While the birth-control pill’s label now informs women of the conflicting studies, the language is confusing, said Elaine Morrato, an assistant professor in the University of Colorado, Denver, Department of Pediatrics. The results are mentioned in a complex paragraph and need to be more easily understood, possibly by using graphics, she said.
Bayer’s Yaz and Yasmin brought in $1.5 billion in sales for the Leverkusen, Germany-based drugmaker last year as its second best-selling product, less than the $1.8 billion in 2009. Teva Pharmaceutical Industries Ltd., based in Petach Tikva, Israel, introduced a generic version of Yaz in May 2010. Bayer’s stock dropped 0.7 percent to 46.13 euros at 9:10 a.m. in Frankfurt.
Women taking drospirenone were 74 percent more likely to experience clots than those on older hormonal contraceptives, the FDA found in a study published in October. Drospirenone is similar to the natural female hormone progesterone. Bayer conducted studies that found no increased risk.
The FDA pushed for more studies on birth control containing drospirenone after an agency staff report concluded on Dec. 6 that the health risks are unclear. A half-dozen studies in all have addressed clotting danger from the products.
The FDA has taken a similar position on Johnson & Johnson’s Ortho Evra birth control patch, which studies have linked to increased chance of clotting.
The same panels evaluating Yaz will consider today how to best interpret studies on the J&J patch and vote on whether Ortho Evra’s benefits outweigh the risks and whether its label accurately reflects potential hazards.
J&J, based in New Brunswick, New Jersey, doesn’t release specific revenue numbers for the patch.
--Editors: Andrew Pollack, Adriel Bettelheim
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