Two new studies published by the British Medical Journal last week showing a significant increased risk of dangerous blood clots for users of oral contraceptives containing the 4th generation progestin drospirenone when compared to users of oral contraceptives containing levonorgestrel. Drospirenone is one of the hormones contained in Yaz, Yasmin, Yasminelle, Beyaz, and the newest addition, Safyral.
The risks to women taking oral contraceptives with drospirenone may be 2 -3 times more likely to suffer from a non-fatal venous thromboembolism (non-fatal VTE) than users of other oral contraceptives. Thromboembolis means a blood clot in the veins, often in the legs, that dislodges and can cause fatal clogging in the lungs' arteries, and may also be called a pulmonary embolism.
The first study, published in the BMJ on April 21, 2011, found that users of oral contraceptives containing drospirenone were two times more likely to suffer from non-fatal VTEs than users of oral contraceptives with levonorgestrel, a 3rd generation progestin. The researchers, Susan Jick and Rohini Hernandez, both affiliated with the Boston Collaborative Drug Surveillance Program, used U.S. claims data to compare the risk of non-fatal VTEs in users of oral contraceptives containing drospirenone versus those containing levonorgestrel. They looked at claims records for women between the ages of 15 and 33, with no other risk factors.
The second study, by Lianne Parkin, Katrina Sharples, Rohini Hernandez, and Susan Jick, was based on data from the British General Practice Research Database. The authors are affiliated with the Department of Preventive and Social Medicine, Dunedin School of Medicine in New Zealand and the Boston Collaborative Drug Surveillance Program. The study concluded that users of an oral contraceptive containing drospirenone were three times more likely to suffer from non-fatal VTEs than users of oral contraceptives with levonorgestrel.
Bayer, the manufacturer of Yasmin, YAZ, Beyaz, and Safyral, immediately issued a press release criticizing these studies, claiming both studies were significantly flawed. Relying upon its own internal studies, Bayer stated, “these studies do not change the overall assessment about the safety of Bayer’s oral contraceptives.”
Bayer currently is facing more than 6,000 lawsuits over its oral contraceptives containing drospirenone. In 2010, Bayer agreed to put additional risk warnings on Yasmin here in the U.S., as well as in Europe. Although sales have slipped, following Bayer’s multi-million dollar advertising campaign, Yasmin remains the top selling oral contraceptive in the United States.