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.

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.