Women taking newer birth control pills that pair estrogen with the synthetic hormone drospirenone, like the popular Yaz and Yasmin pills made by Bayer, have been found to have a 75 percent greater chance of getting a life-threatening blood clot than women taking an older formulation of the pill, the FDA says.
In a new study released Thursday, the U.S. Food and Drug Administration took a look at the medical histories of more than 800,000 U.S. women who were using various contraceptive products between 2001 and 2007. They found that, on average, women taking Yaz were far more likely to experience a blood clot than women taking birth control drugs with older, more well-tested formulations.
All birth control pills contain synthetic estrogen, but different drug companies combine estrogen with other different types of a synthetic version of the hormone progestin. These combination pills work by preventing ovulation, thickening cervical mucus in order to prevent sperm from reaching the egg, and thinning the lining of the uterus so that it's difficult or impossible for a fertilized egg to implant.
Dropsirenone is a newer version of synthetic progestin, and is known to increase potassium levels in the blood. Potassium is necessary for good nerve and muscle function, but too much of it in the blood stream-a condition known as Hyperkalemia-can cause muscle fatigue, weakness, paralysis, abnormal heart rhythms, and nausea. Drospirenone is used in several other birth control pills, including Yasmin, Beyaz, Safyral, Syeda, Loryna, Ocella, and Zarah, the Associated Press reported.
Other recent studies seem to back up the FDA's clams. In a new study published earlier this week in the British Medical Journal, Danish researchers followed more than 1 million women age 15 to 49 for nearly 10 years and found that women taking Yaz and other newer forms of hormonal birth control had twice the risk of blood clots as women using an older synthetic hormone called levonorgestrel. (Two studies conducted in 2007 found no difference in blod-clot risks, though.)
Bayer Healthcare released a statement saying that it "is currently evaluating this publication and cannot comment at this point in time."
Pills aren't the only hormone-based birth control with potential problems.The FDA also found that women using the Ortho Evra patch and the Nuvaring vaginal contraceptive ring had higher rates of complications. Both of those products combine estrogen with synthetic hormones that are considered to be "next generation" ones, approved for use only within the last decade or so.
The FDA is planning to hold a meeting with scientific advisers to discuss drug safety on December 8.
"At a certain point we have to ask why the FDA continues to approve drugs that are less safe and have no benefit compared to drugs already on the market," said Dr. Diana Zuckerman, president of the National Center for Women and Families, a consumer group for women's health issues. "With all these different birth control options, why take the most expensive one that can also kill you?"
This isn't the first problem the FDA has had with Yaz. In 2009, the FDA ordered Bayer to change its TV ads for the popular birth control pill because, according to the FDA, Bayer had overstated the pill's ability to prevent acne and PMS.
Also on Shine: