Safety of birth control pills under scrutiny

By Dr. Ananya Mandal, MDJun 5 2011

Bayer’s oral contraceptive pills are being reviewed by regulators after some studies suggested they may cause more blood clots than competing medicines.

This comes from two latest studies in the British Medical Journal that show a twofold to threefold greater risk of blood clots in women taking pills like Bayer’s Yaz, the Food and Drug Administration said last Tuesday in a statement. European regulators said that they were revising the products’ prescribing information to include the new safety findings.

The FDA said that while all birth control pills pose a risk of blood clots this new scrutiny will look into the hormone drospirenone, found in Bayer’s Yaz, Yasmin, Beyaz and Safyral. The agency expects to have results later this summer of an 800,000-person study it commissioned to examine the risks.

The FDA said some previous studies have reported that the risk of blood clots for women who use birth-control pills containing drospirenone is higher than that for women who use birth-control pills containing levonorgestrel, while other studies haven't found such a risk. While the risk of blood clots is low among women who take birth-control pills, the FDA said it is higher than the risk among women who aren't taking the pills.

Meanwhile doctors and patients have been warned to look for symptoms of blood clots, including leg or chest pain.Blood clots form inside a vein and are known as deep vein thrombosis, or DVT. The clots usually form in the lower leg or thigh, but can break loose and travel to other areas of the body such as the lungs, where they are called a pulmonary embolism, or PE. The FDA said the symptoms of a DVT include the new onset of persistent leg pain, while those of a PE include severe chest pain and sudden shortness of breath.

The Yaz family of products generated $1.47 billion in sales last year for Bayer, or 3.3 percent of the company’s revenue. Bayer in response said, “Patient safety is Bayer’s top priority…Bayer’s analysis of the overall body of available scientific evidence continues to support its current assessment about the safety of its oral contraceptives.”