Norgestrel is synthetic steroidal progestin that is used in combination with ethinyl estradiol for oral contraception. Norgestrel is composed of a racemic mixture of two stereoisomers, dextronorgestrel and levonorgestrel. However, only the levorotary enantiomer (levonorgestrel) is biologically active. Norgestrel (and more specifically the active stereoisomer levonorgestrel) binds to the progesterone and estrogen receptors within the female reproductive tract, the mammary gland, the hypothalamus, and the pituitary. Once bound to the receptor, progestins like levonorgestrel will slow the frequency of release of gonadotropin releasing hormone (GnRH) from the hypothalamus and blunt the pre-ovulatory LH (luteinizing hormone) surge. Loss of the LH surge inhibits ovulation and thereby prevents pregnancy. Norgestrel in combination with ethinyl estradiol is indicated for the prevention of pregnancy in women who elect to use this product as a method of contraception.

Norgestrel,(+) (dextronorgestrel) is the biologically inactive isomer of norgestrel. Dextronorgestrel showed no ability to displace labelled levonorgestrel from the sex hormone binding globulin sites. In vitro active form being converted mainly to the 16 beta-hydroxysteroid and inactive form to the 16 alpha-hydroxysteroid. There was practically no binding to dextronorgestrel of dextronorgestrel to a cytoplasmic receptor prepared from the myometrium of estrogenized immature female rabbits was investigated. While some medications may contain dextronorgestrel, they are often labeled in terms of their levonorgestrel content only, ignoring the inert isomer.

Norelgestromin, the progestin, 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. Johnson & Johnson developed an adhesive female contraceptive patch that contains ethinylestradiol (0.75mg) and the progestogen norelgestromin (6mg). his product is a combination contraceptive acting via the inhibition gonadotropins. Its primary mechanism of action involves the suppression of ovulation, including changes in the cervical mucus and endometrium. The patch delivers a continuous flow of hormones through the skin and into the bloodstream. The contraceptive patch is available in countries worldwide.

Norgestimate is a steroidal progestin of the 19-nortestosterone group that is used in combination with ethinylestradiol as an oral contraceptive and for treatment of acne. and in combination with estradiol in menopausal hormone replacement therapy. Norgestimate shows high selectivity for the progesterone receptor and low androgenic activity.

Norgestrel is synthetic steroidal progestin that is used in combination with ethinyl estradiol for oral contraception. Norgestrel is composed of a racemic mixture of two stereoisomers, dextronorgestrel and levonorgestrel. However, only the levorotary enantiomer (levonorgestrel) is biologically active. Norgestrel (and more specifically the active stereoisomer levonorgestrel) binds to the progesterone and estrogen receptors within the female reproductive tract, the mammary gland, the hypothalamus, and the pituitary. Once bound to the receptor, progestins like levonorgestrel will slow the frequency of release of gonadotropin releasing hormone (GnRH) from the hypothalamus and blunt the pre-ovulatory LH (luteinizing hormone) surge. Loss of the LH surge inhibits ovulation and thereby prevents pregnancy. Norgestrel in combination with ethinyl estradiol is indicated for the prevention of pregnancy in women who elect to use this product as a method of contraception.