One popular form of contraceptive has been found to decrease specific arterial function that is vital to good cardiovascular health.  The study raises the question of the safety in using the contraceptive today at the risk of developing cardiovascular disease later.

The contraceptive, synthetic progestin medroxyprogesterone acetate (MPA), is a component of Depo/Provera, an injectable contraceptive favored by millions of young women for its long-lasting effect.  It is estimated that 80% of American women have used oral contraceptives at some point in their lives.

Other women use MPA in the form of Provera, where it is the active ingredient, to relieve menopausal discomfort, regulate menstrual cycles, and treat abnormal uterine bleeding.  MPA is the drug used in the discontinued hormone replacement therapy (HRT) study, the Women’s Health Initiative.  The study was discontinued due to concerns over the cardiovascular consequences of the HRT.

The current study, conducted at the Exercise and Environmental Physiology Laboratories of the University of Oregon, studied the effects on 14 women, aged 19 to 27, using estradiol, a form of estrogen, and an oral contraceptive that also includes MPA.

The estradiol alone was found to improve the function of the endothelial tissue in the brachial artery of the arm.  Endothelial tissue is vital to the flexibility of the arterial walls, allowing them to expand and contract as needed for optimum blood circulation.  Impaired function of the endothelium is an indicator of atherosclerosis, a form of cardiovascular disease.

When the MPV was taken, the positive effects of estradiol were reversed and endothelial function suffered.  Function was assessed by measuring levels of a peptide, endothelin-1, which promotes cellular division and helps to ease inflammation.  The estradiol lowered the peptide levels in study participants but it increased by a substantial measure when MPA was added.

While leading researchers to question a link between oral contraceptive use and the increasing rate of cardiovascular disease in women, they are quick to point out that this study is merely the starting point of extensive research to follow and that no changes to current contraceptive practices should be made at this time, according to Dr. Paul F. Kaplan, co-author of the report describing the study results.

The full details of the report are available online and will be published in the regular edition of the journal, Heart and Circulatory Physiology.

Source: University of Oregon