BOSTON — The route of hormonal contraceptive administration—transdermal or oral—does not make a difference in terms of the hormone's effect on plasma lipids and lipoproteins, according to the findings of a randomized crossover trial.
In the study, women on either a standard or extended-release contraceptive patch had higher levels of HDL cholesterol and its constituent apolipoprotein A1 (ApoA1), compared with when they were taking oral contraceptives; however, the effects of patch and oral formulations on atherogenic lipoproteins were similar, Dr. Elizabeth Chan reported at a symposium sponsored by the International Atherosclerosis Society.
“Patch contraception results in 60% higher estrogen levels than oral contraception. It is the estrogen/progestin ratio that determines the overall lipoprotein effects in hormonal contraception formulations,” according to Dr. Chan of the University of Washington division of cardiology in Seattle and her colleagues.
Thirty-five healthy premenopausal women had a 2-month phase-in period on an oral contraceptive (Ortho-Cyclen; 35 mcg ethinyl estradiol and 0.25 mg norgestimate) and were then randomly assigned in a three-way crossover design to 2 months on the oral contraceptive, a patch formulation (Ortho-Evra, approximating a daily dose of 20 mcg ethinyl estradiol and 150 mcg norelgestromin), or an extended-release patch (Extended Ortho-Evra, 7-week patch application plus 1 week off). Investigators were blinded to treatment assignment.
A total of 31 women completed all three treatments and were available for the final analysis. Lipoprotein levels were measured on the 21st day of the second month of each treatment cycle, corresponding to peak hormonal effect.
The investigators found that the use of the standard patch formulation resulted in significantly higher levels of the favorable lipids—HDL and ApoA1—compared with oral administration. The extended patch also had a significantly greater effect on HDL and ApoA1, compared with the standard patch. But for all other lipid parameters—LDL, non-HDL cholesterol, apolipoprotein B, and triglycerides—there were no significant differences among the three contraceptive formulations.
“The higher HDL cholesterol and ApoA1 seen with patch contraception may involve differences in formulation and/or reverse cholesterol transport. These mechanisms require further study.” said the researchers, who reported no conflicts of interest related to the study supported by Ortho-McNeil, maker of the contraceptives tested.