Imperfect use of
contraceptive methods notably increases the likelihood of pregnancy. One means of improving user adherence with
hormonal contraception is to minimize the dosing schedule. Two forms of hormonal
contraceptive have currently achieved this goal: the
transdermal patch and the
vaginal ring. The first and only transdermal
contraceptive patch to receive worldwide regulatory approval (ethinylestradiol/
norelgestromin) is a convenient approach to
contraception that has a similar efficacy to
oral contraceptives (OCs), but with the benefit of once-weekly administration. In addition, transdermal delivery of
contraceptive hormones eliminates variability in gastrointestinal absorption, avoids hepatic first-pass metabolism, and prevents the peaks and troughs in serum concentrations that are seen with OCs.
Norelgestromin, the
progestin contained in the patch, is the active metabolite of
norgestimate and is structurally related to
19-nortestosterone.
Norgestimate and
norelgestromin mimic the physiologic effects of
progesterone at the
progesterone receptor; however,
norelgestromin has negligible direct or indirect androgenic activity, suggesting that it may be suitable for women with disorders related to
androgen excess (such as
hirsutism,
acne, and
lipid disorders).
Contraceptive effectiveness is usually a function of the efficacy of a
contraceptive in combination with compliance with its dosing regimen. The efficacy of the
contraceptive patch has been clearly demonstrated in three phase III trials, two of which were randomized comparisons with an OC. The likelihood of pregnancy was similar between these
contraceptive methods; however, compliance with the patch was notably better, particularly in younger women. The safety and tolerability profile of the patch was similar to that of the OC. A cost-effectiveness analysis has suggested that the
contraceptive patch is more cost effective than the OC, due to decreased costs related to unwanted pregnancy.