Bayer's new-generation contraceptives Yasmin and Yaz may be riskier than older birth-control pills, according to two new studies. In one study, based on U.S. medical claims data, researchers found that the risk of venous thromboembolism doubled in women using contraceptives that contain drospirenone, one of the hormones found in Yasmin, compared with women using the older synthetic hormone levonorgestrel. Another study, using British data, found a threefold risk, Reuters reports.
Bayer disputed the studies, saying their methodologies had "significant flaws." The company said that the new data doesn't change "the overall assessment about the safety of Bayer's oral contraceptives, citing "the already large and robust scientific body of evidence" on their use. Some previous studies have found an increased risk of clots--and in March of last year, the company added a warning on the European label for Yasmin--but other studies have shown the Yasmin products to be as safe as levonorgestrel.
The study authors, however, said that their data should be weighed carefully. It "provide(s) further evidence that levonorgestrel oral contraceptives appear to be a safer choice," Boston University's Susan Jick said (as quoted by Pharmalot). And Lianne Parkin, senior author of the second study, suggested that levonorgestrel products should be used as first-line contraceptives.
Bayer faces thousands of lawsuits over the safety of Yaz and Yasmin. The lawsuits accuse Bayer of marketing the contraceptives heavily without mentioning that they carried higher risks than other birth-control pills. FDA did warn Bayer in 2008 that its TV commercials didn't adequately disclose the pills' risks, and the company produced a new series of ads to correct the ones FDA called misleading.