A new study has found that the use of drospirenone-containing oral birth control pills significantly increases the risk of blood clots, both deep vein thrombosis and pulmonary embolism.
All oral contraceptives are associated with a higher risk of blood clots, but there is conflicting information about the risk of adverse events with drospirenone.
Many previous studies have evaluated risks of second- and third-generation contraceptives, which both contain derivatives of testosterone.
The researchers at the Pharmacoepidemiology and Pharmacogenetics Unit, Department of Community Medicine and Epidemiology, Office of Chief Physician, Clalit Health Services Headquarters, Tel Aviv, Israel, undertook a study to determine the risk of venous and arterial blood clots in various oral contraceptive users.
They looked at data on 329 995 women in Israel aged 12 to 50 years who received oral contraceptives between January 2002 and December 2008 and followed them until 2009.
The researchers found an elevated risk of venous thrombotic events for drospirenone users compared with second- and third-generation contraceptives.
Risk was highest in the early months of use.
“Use of drospirenone-containing combined oral contraceptives was associated with a significantly increased risk of venous thrombotic events (deep vein thrombosis and pulmonary embolism) but not arterial thrombotic events (transient ischemic attack and cerebrovascular accident), relative to use of second- or third-generation combined oral contraceptives,” stated the researcher Dr. Naomi Gronich and co-authors.
The finding has been published in the Canadian Medical Association Journal.