By Alina Selyukh
WASHINGTON (Reuters) - Health officials are weighing stricter labels on the widely used new generation of birth control pills, based on data showing they may put women at a higher risk of dangerous blood clots.
U.S. Food and Drug Administration staff reviewed studies comparing an older generation of birth control with newer pills that contain the compound drospirenone, such as Bayer AG's popular Yaz and Yasmin.
In a report released on Tuesday, the reviewers said the body of evidence shows conflicting data on a link between pills containing drospirenone and blood clots, but the link could not be ruled out either and that fact may warrant a new label.
"Because of the consistency in recent reports for an increased risk, product labeling should reflect that very real possibility," they said. A panel of outside experts advising the FDA is due to vote on the labels on Thursday.
Most common contraceptive pills combine the hormones estrogen and progestin, which help block ovulation and sperm. They can also increase the chance of a woman getting blood clots than if she didn't take birth control pills, particularly as she ages.
"While it's rare, it's heartbreaking when this happens. When there are safer options available, we can't let this continue," said Cynthia Pearson, executive director of the National Women's Health Network, one of several consumer advocacy groups that argue the drugs should be taken off the market entirely.
Drawing a definitive conclusion that adding drospirenone elevates the risk has been also complicated by the fact that risk of blood clots also goes up if a woman smokes, has clogged arteries, a family history or other health problems.
HIGHER RISK OF DANGEROUS CLOTS
An FDA study earlier this year found a higher risk of venous thromboembolisms (VTEs) in women, especially those younger than 35, who were taking Yasmin. A similar conclusion was drawn about Johnson & Johnson's Ortho Evra contraceptive patch, which does not contain drospirenone. FDA advisers will discuss Ortho Evra on Friday.
With VTEs, a blood clot occurs in one of the deep veins in the body, such as the leg or pelvis, and then travels to the lungs. The study also reported a higher risk of arterial thrombotic events, or ATEs, in older women on Yasmin. VTEs and ATEs can significantly increase the risk of strokes or death.
Court documents unsealed on Monday allege that Bayer failed to inform the FDA or the public about adverse VTE events linked to Yasmin before the drug was approved in May 2001. Former FDA Commissioner David Kessler is expected to testify in upcoming trials against Bayer that the company, Germany's largest drugmaker, withheld reports of dangerous blood clots.
Yaz, a reformulated version of Yasmin, remains one of the top-selling contraceptives in the United States. Bayer raked in $374 million in Yaz sales last year and twice as much at the peak of Yaz's popularity in 2009, according to data from IMS Health.
The number of prescriptions filled for Yaz also dropped more than by half to 5 million in 2010 from 11 million in 2009, according to IMS.
The company makes newer Beyaz and Safyral pills, versions of Yaz and Yasmin that add levomefolate to raise levels of folate, which is thought to help fertility.
Apart from preventing pregnancy, Yaz and Beyaz also have a secondary indication to treat moderate acne and symptoms of premenstrual dysphoric disorder, a severe mood problem.
In briefing documents for the FDA advisers, Bayer maintains that when used according to the label, benefits of using Yaz and its other drospirenone-containing pill outweigh the risks.
Labels now include a boxed warning that smoking increases the risk of serious cardiovascular problems, especially in women over 35. Warnings also highlight higher risk of blood clots associated with birth control pills.
(Additional reporting by Anna Yukhananov in Washington; Editing by Michele Gershberg and Steve Orlofsky)