June 1, 2011 — FDA is conducting a safety review of birth control pills containing the hormone drospirenone to see if they increase the risk of blood clots more than birth control pills containing levonorgestrel, the agency said in a statement on Tuesday, the Wall Street Journal reports. Both drospirenone and levonorgestrel are forms of progestin (Corbett Dooren, Wall Street Journal, 5/31).
Two studies published recently in the British Medical Journal found that women taking pills containing drospirenone -- found in Bayer's Yaz, Yasmin, Beyaz and Safyral -- had a two to three times greater risk of blood clots (Bloomberg/New York Times, 6/1). FDA noted that some other studies have found similar results and some have not.
FDA said it is "currently evaluating the conflicting results from these studies and will look at all currently available information to fully assess the risks and benefits of drospirenone-containing birth control pills." The agency is in the process of finalizing and reviewing a study involving more than 800,000 women to explore the association of blood clots with hormonal contraception. Results are expected later this summer.
Last week, the European Medicines Agency said the risk of developing blood clots was slightly higher for women taking birth control pills containing drospirenone than for women taking pills with levonorgestrel.