The studies will hurt Bayer as it faces 6,850 lawsuits alleging that Yaz's drospirenone ingredient is more dangerous than those used in competing pills. About 190 deaths from heart attack, stroke or pulmonary embolism have been associated with Yaz and similar pills.
Two of the studies looked at blood clots; the third looked at gall bladder disease:
- In the U.S., researchers looked at a database containing almost all women who took an oral contraceptive containing either drospirenone (Yaz) or levonorgestrel since 2002. It found a 2.3 times greater risk of blood clots with drospirenone.
- In the U.K., researchers found 3.3 times more blood clots in drospirenone users.
- And in Canada, researchers looking at U.S. data found "a small, statistically significant increase" in the risk of gallbladder disease but they concluded it was "unlikely that these differences are clinically significant."
The FDA does not require companies to wait until it asks for new risk warnings to be added, but it is rare for a company to voluntarily tighten the instructions for its drugs on their own. Doing so is an admission that the company knows there is a problem, and companies don't like making such admissions. Nonetheless, courts have not looked kindly on companies that failed to act after they learned of problems on their products.
It is unlikely that Bayer will do anything to alert doctors to think more carefully before prescribing Yaz and its sister brands (Yasmin, Beyaz, Natazia, Angeliq and Ocella). The company already sponsored guidelines to ob/gyns suggesting the drug is no more risky than others; previous studies have gotten contradictory results; and Yaz is Bayer's second-biggest product by sales.
- UPDATE: In a statement, Bayer dismissed the two BMJ studies on methodological grounds.