These synthetic progestins will compete with progesterone receptor binding sites and compete with progesterone rendering progesterone useless.

这些合成的会与接收器竞争，并使无。

Approved by the FDA in 2001, the patch is sold by prescription and releases ethinyl estradiol (a type of estrogen), and a progestin called norelgestromin via the skin into the bloodstream.

FDA在2001年就已经证实，这种通过肤来释放雌激和孕激的贴膜是一种处方类药物。