Nearly six months after a pair of studies found that women taking birth control pills containing a hormone called drospirenone are more likely to develop blood clots than those who take an older oral contraceptive, the FDA has decided to hold an advisory panel meeting in December to review the risks and benefits.
Meanwhile, the agency is continuing to review a separate agency-funded study that evaluated the risk of blood clots in users of several different hormonal birth control products (contraceptives). Preliminary results suggest an approximately 1.5-fold increase in the risk of blood clots for women who use drospirenone-containing birth control pills compared to users of other hormonal contraceptives.
And so, the agency will convene the Reproductive Health Drugs Advisory Committee and the Drug Safety and Risk Management Advisory Committee to examine the risk of blood clots of drospirenone-containing birth control pills. The most widely known oral contraceptives containing this hormone are the Yaz and Yasmin pills sold by Bayer.
The scrutiny is not good news for Bayer. Nearly 7,000 lawsuits are pending in the US over alleged injuries and deaths relating to Yaz and Yasmin, as well as generics. The lawsuits allege Yaz and Yasmin have risks beyond those of traditional birth control pills and Bayer too aggressively promoted the pills without disclosing higher risks. Bayer was warned by the FDA in 2008 that TV ads were misleading and did not disclose added risks (see here) and recently was chastised in the UK for running a Yasmin ad that boasted the pill could prove beneficial on the same problems it may cause (read this).
As to the data, the FDA says it reviewed six published epidemiologic studies that evaluated the risk of blood clots in women using birth control pills containing drospirenone, but generated conflicting findings. Two were postmarketing studies required by the FDA or European regulators, and did not report any difference in clot risk between the pills and products containing levonorgestrel or other progestins. But two studies in 2009 reported a 1.5- to 2-fold higher risk in women who use pills containing drospirenone as opposed to contraceptives containing levonorgestrel.
More recently, two articles published in 2011 in the British Medical Journal reported a 2- to 3-fold greater risk of clots in women using oral contraceptives containing drospirenone rather than levonorgestrel. However, the FDA notes these were epidemiological studies and, so far, has not reached a conclusion on the risk for blood clots, but remains concerned about a potential increased risk (here is the FDA statement).
UPDATE: A Bayer spokeswoman sends us this response to the FDA move: "While Bayer was aware that the FDA was funding this study, Bayer has not yet had the opportunity to see and analyze the data from the FDA funded study. We look forward to a robust discussion about these complex issues in the appropriate scientific discussion at the FDA Advisory Committee meeting in December."