FDA Still Reviewing Blood Clot Risk for Drospirenone Birth Control Pills

September 27, 2011 — FDA in a statement on Monday said it "remains concerned" that birth control pills containing the hormone drospirenone could heighten the risk of blood clots more than other oral contraceptives, but it has not reached a final conclusion on the matter, the Wall Street Journal reports (Corbett Dooren, Wall Street Journal, 9/27). Drospirenone is a form of progestin found in Bayer's Yaz, Yasmin, Beyaz and Safyral birth control pills.

Earlier this year, FDA launched a safety review after two studies published in the British Medical Journal found a two to three times greater risk of blood clots associated with birth control pills containing drospirenone compared with birth control pills containing levonorgestrel, another type of progestin (Women's Health Policy Report, 6/1).

After conducting its own review involving 800,000 women, FDA on Monday said that preliminary results suggest a 1.5 greater risk of clots associated with drospirenone-containing contraceptives. However, six other studies show conflicting results, with some data showing a higher risk and others showing no increased risk (Wall Street Journal, 9/27). "As with all epidemiologic studies, there are methodological issues that make interpretation of these conflicting results complex," FDA said (Gever, MedPage Today, 9/26).

Bayer has said its analysis of available scientific evidence shows that the risk of developing a blood clot associated with pills containing drospirenone "is comparable" with that of other birth control pills. The Journal notes that sales of Bayer's Yaz have declined in recent months, which the company attributes to generic competition (Wall Street Journal, 9/27).

FDA said its Reproductive Health Drugs Advisory Committee and its Drug Safety and Risk Management Advisory Committee will meet Dec. 8 to discuss the available data and the final results of the FDA-commissioned epidemiologic study. Meanwhile, agency officials advised health care providers to inform women about the potential risk of blood clots associated with drospirenone-containing pills (MedPage Today, 9/26).