A new low-dose, once-a-week contraceptive transdermal delivery system (TDS) with 2.3-mg ethinyl estradiol (EE) and 2.6-mg levonorgestrel (LNG; Twirla®) has recently been approved by the US FDA for contraception of women with BMI <30 kg/m2. The rationale for developing this new patch, the preclinical study results and the results from two innovative Phase III clinical trials demonstrate that this patch has an acceptable Pearl index (4.3%) for its indicated users and has safety and tolerability comparable to other similar dose oral combined hormonal contraceptives. This new TDS provides an improvement over the existing TDS products, with significantly lower steady-state estrogen exposure, a level equal to that with 30-µg EE containing oral contraceptives.
Keywords: birth control; TDS; contraceptive patch; ethinyl estradiol; hormonal contraception; levonorgestrel; skinfusion technology.
Lay abstract A new patch with lower doses of estrogen than existing contraceptive patches has been approved by the US FDA for birth control for women who are not obese. It has been tested in two large clinical trials that included women who are like the general population of reproductive age women in the USA. Up-to-date electronic diaries were used to get the most accurate information to use to counsel women who might appreciate the convenience of once-a-week patch use. The patch worked better in lighter women than those who were heavier, and it appears to be safer in women with lower BMIs too.