Thrombosis due to hormonal contraception: risk factor contraceptive pill

Birth control pills containing drospirenone may carry a higher risk of thrombosis. In the USA, more attention must now be drawn to this fact.

Is there a risk of thrombosis in the contraceptive pill? Image: AllzweckJack/photocase.com

When Susan Tabbach woke up in January 2009 with a pain in her left breast in the middle of the night, her first thought was of sore muscles. The then 29-year-old had just come from a skiing vacation.

The architect from Aachen would never have suspected a pulmonary embolism and attributed it to taking Yasminelle, a drospirenone-containing pill from Bayer. It was only after five days that doctors made the diagnosis: a blood clot had blocked a blood vessel in her lung. It took Tabbach a year and a half to fully recover.

In Germany, the so-called "third generation" pills, which include Bayer’s Yasmin, Yasminelle and Yaz preparations, are considered to be very popular hormonal contraceptives. They are so popular because of the positive side effects associated with the drospirenone they contain. Basically, every contraceptive pill consists of the hormones progestins and estrogens.

Drospirenone was originally developed by Bayer as a replacement for the naturally occurring progestogen progesterone. The advantage of drospirenone is that it prevents the deterioration of skin appearance and weight gain that pill users have long complained about.

Three times higher risk of thrombosis

But ever since Schering AG, which has since been merged into BayerHealth Care, launched the drug on the market in 2000, the artificial progestin has been controversial. The U.S. Food and Drug Administration (FDA) announced at the beginning of April that some studies had shown that the risk of thrombosis among users of these preparations was three times higher than among women not taking drospirenone.

Other studies, however, did not clearly show this relationship. Nevertheless, the FDA called on Bayer to revise the package inserts for Yasmin and similar products. In the future, the preparations in the U.S. must be labeled "Women over 35 who smoke should not use Yasmin."

The exact number is unknown

According to the German Federal Ministry of Health, product information for pills containing drospirenone was already adjusted in Germany in 2011. "They sufficiently reflect the risks described," says ministry spokesman Oliver Ewald.

Last year, for example, Bayer had the following paragraphs added to the German-language product information for Yasmin: "Out of every 100,000 women who use a pill such as Yasmin, 30-40 women may develop a blood clot within one year. The exact number is unknown. The level of risk may vary depending on the type of pill. Discuss available options with your doctor."

Bayer itself points to disagreement about thrombosis risk in the scientific community. "Some studies concluded that there is no difference between progestins, according to others there is," said Friederike Lorenzen, Bayer HealthCare spokeswoman. In addition, she said, all of Bayer’s oral contraceptives, including those containing drospirenone, have a positive benefit-risk profile when taken according to their indications.

Already developed 50 years ago

The German Society of Gynecology and Obstetrics (DGGG) and the Professional Association of Gynecologists (BVF) nevertheless suspect that "combined anticonceptives containing drospirenone may carry a higher risk of thrombosis than those containing levonorgestrel or norethisterone." The associations said this in a joint press release.

Levonorgestrel and norethisterone are considered first- and second-generation synthetic progestins and were developed back in the 1950s and 1960s. However, neither substance has the positive side effects of drospirenone.

According to the DGGG, drospirenone probably increases the risk of thrombosis because it leads to slightly increased water excretion. "This can lead to a slight weight loss, although not to a loss of fatty tissue," he says at the professional society.

Overweight as a risk factor

Because of this property, drospirenone-containing anticonceptives are increasingly used by overweight women. The additional dehydration could thicken the blood and thus increase the risk of thrombosis. However, obesity and lack of exercise are already a risk factor for the development of thromboses and embolisms.

According to the professional associations, therefore, it cannot currently be ruled out that the presumably increased risk of thrombosis with drospirenone use primarily reflects the increased risk of thrombosis associated with obesity and lack of exercise.

DGGG and BVF therefore advise users to exclude all factors that could additionally increase the risk of thrombosis, such as smoking, obesity or the possibility of a genetically determined coagulation disorder, together with the gynecologist before choosing a contraceptive.

Damage to health and even death

For women like Susan Tabbach, that’s not enough. She is calling on Bayer to take these preparations off the market. "A drug that carries such risks should not be sold at all," Tabbach says.

In the U.S., Bayer was hammered with criticism following the FDA’s decision. 11,300 lawsuits had been filed there by Feb. 1. The causes of action range from health damage to death, due to the use of the drospirenone-containing preparations. The Bayer Group has already reached settlement agreements in principle with 170 female users in the United States. Similar agreements between patients in this country and the pharmaceutical giant are not known.

In Germany, the Federal Institute for Drugs and Medical Devices (BfArM) has so far received 15 reports of deaths in connection with the use of contraceptives containing drospirenone. As a member of the "Risk Pill" self-help group, Susan Tabbach will continue to work with other drospirenone-affected women for more education by gynecologists, the adoption of intolerance tests before prescribing these drugs.

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