FDA Still Reviewing Clot Risk for Birth Control Pills
September 27th, 2011 // 12:13 pm @ jmpickett
Four months after announcing that it was reviewing the safety of certain drospirenone-containing oral contraceptives, following reports of heightened risk for blood clots, the FDA said Monday that it still had not reached a conclusion.
Data from a large FDA-funded epidemiologic study have now undergone preliminary analysis and suggest a 1.5-fold increase in venous thromboembolism (VTE) risk associated with the drospirenone-containing contraceptives, the FDA said.
Nevertheless, the agency is not yet prepared to state conclusively that these products — sold under five different brand names — pose a risk to women.
Before making changes to the drugs’ labeling or restricting access to them, the agency plans to have two of its advisory committees review the available data at a joint meeting in December.
On May 31, the FDA said it was studying clot risk in birth control pills combining drospirenone and ethinyl estradiol, after some studies had found an approximately 50% higher rate of VTE in women taking these agents relative to other oral contraceptives such as levonorgestrel.
At the time, the agency indicated that it was hesitating on actions because there was no increase in risk in two postmarketing studies it and European agencies had ordered.
Now the FDA has reviewed a total of six epidemiological studies, four of which found a higher VTE risk. One of these put the absolute risk at about 30 per 100,000 person-years of exposure, versus 12.5 per 100,000 for levonorgestrel-based contraceptives.
“As with all epidemiologic studies, there are methodological issues that make interpretation of these conflicting results complex,” the agency said Monday.
“FDA has not reached a conclusion on the risk for blood clots in women using drospirenone-containing birth control pills, but remains concerned about the potential increased risk.”
It also noted that all the studies of drospirenone and VTE have focused on products containing 0.03 mg of ethinyl estradiol. There are several other drospirenone contraceptives that include a lower dose of ethinyl estradiol (0.02 mg). All products in both groups contain 3 mg of drospirenone.
“It is unknown at this time whether the reported VTE risk applies to all drospirenone-containing products,” the FDA indicated.
Drospirenone-containing products with the higher estrogen dose include Yasmin, Zarah, Syeda, Safyral, and Ocella.
Those with the lower amount of estrogen include Yaz, Loryna, Gianvi, and Beyaz.
The FDA’s Reproductive Health Drugs Advisory Committee and its Drug Safety and Risk Management Advisory Committee will meet Dec. 8 to discuss the data, including a final report on the FDA-commissioned epidemiologic study, which covers some 800,000 women taking oral contraceptives.
In the meantime, the agency advised health professionals to inform women taking drospirenone-containing products of the potential clotting risk.
Smoking, being overweight, and having a family history of clotting disorders are all risk factors for VTE that should be discussed with patients, the agency noted.
