Birth Control Pill Blood Clot Risk Higher Among Some Drugs: Study

New research suggests that many women do not use the safest available types of oral contraceptives, with many of the most popular birth control pills, such as Yaz and Yasmin, carrying a higher risk of blood clots.

The study, published today in the British Medical Journal, found that oral contraceptives containing desogestrel, cyproterone acetate or drospirenone were up to twice as likely to cause blood clots in women as birth control pills containing levonorgestrel and low doses of estrogen. The study found that switching to the safer forms of birth control, like Bayer AG’s Microgynon 30 that contains levonorgestrel, reduced health risks while keeping the same level of pregnancy prevention.

The newer birth control pills Yaz and Yasmin, which both contain drospirenone, accounted for approximately 28.7% of the market in 2008 due to heavy marketing. Although direct-to-consumer advertisements suggested that the Yasmin and Yaz blood clot risks are on par with other birth-control pills, this study provides further evidence that these newer drugs may be more dangerous and provide minimal, if any benefits, over other available birth control pills.

Researchers at Leiden University Medical Center in the Netherlands studied the effects of several different brands of birth control pills on more than 3,000 women and determined that birth control pills using newer forms of progestin had a much greater chance of causing blood clots, or thrombosis, than other pills.

The data indicates that users of Yaz, Yasmin and other birth control pills containing drospirenone face a 6.3 times increased risk of blood clots when compared to women who were not on the pill. In comparison, women who took oral contraceptives containing levonorgestrel, were found to have the lowest risk of blood clots, with just below a fourfold increase over those taking birth control pill.

The highest risk was seen among users of oral contraceptives that used desogestrel, such as Marvelon, which had 7.3 times the risk of blood clots. Desogestrel, considered a “third generation” progestin, has come under fire from critics due to its health risks, with the consumer advocacy group, Public Citizen, calling for an FDA ban on all such oral contraceptives.

All of the medications involved in the study were found to be equally effective at preventing pregnancy, which led researchers to recommend that doctors, except in circumstances where the patient has special needs, should default to prescribing the safest birth control medication available.

Currently Microgynon 30 ranks as the 11th best-selling birth control pill on the market, with first-quarter sales of about $168 million. Yaz, Yasmin, and a low-dose version of Yasmin called Yasminelle, brought in a $1.86 billion in sales during the first quarter by comparison.

Bayer, which sells both Yaz and Yasmin, has come under fire lately for failing to adequately warn about the potential risks associated with the birth control pills and making misleading statements in consumer advertisements. Earlier this year, they agreed to run a $20 million “corrective” advertising campaign as part of a settlement with drug regulators and states attorneys from 27 states over their deceptive marketing.

A number of consumers who have suffered heart attacks, strokes, gallbladder disease and severe blood clots like deep vein thrombosis (DVT), pulmonary embolism or death, have filed Yaz lawsuits and Yasmin lawsuits against Bayer for failing to warn consumers and the medical community about the potential risk of side effects. The complaints suggest that Bayer placed their desire for profits before patient safety by ignoring potential Yasmin and Yaz problems while pushing to increase their market share for the drugs.