Norethisterone

Norethisterone, also known as norethindrone and sold under the brand name Norlutin among others, is a progestin medication used in birth control pills, menopausal hormone therapy, and for the treatment of gynecological disorders.^[11][13] The medication is available in both low-dose and high-dose formulations and both alone and in combination with an estrogen.^[13][14] It is used by mouth or, as norethisterone enanthate, by injection into muscle.^[11][13][15]

Side effects of norethisterone include menstrual irregularities, headaches, nausea, breast tenderness, mood changes, acne, increased hair growth.^[16][17] Norethisterone is a progestin, or a synthetic progestogen, and hence is an agonist of the progesterone receptor, the biological target of progestogens like progesterone.^[11][13] It has weak androgenic and estrogenic activity, mostly at high dosages, and no other important hormonal activity.^[11][18]

Norethisterone was discovered in 1951 and was one of the first progestins to be developed.^[19][20][21] It was first introduced for medical use on its own in 1957 and was introduced in combination with an estrogen for use as a birth control pill in 1963.^[21][22] It is sometimes referred to as a "first-generation" progestin.^[23][24] Like desogestrel and Norgestrel, Norethisterone is available as a progestogen-only "mini pill" for birth control.^[25][26][27] Norethisterone is marketed widely throughout the world.^[28] It is available as a generic medication.^[29] In 2022, it was the 135th most commonly prescribed medication in the United States, with more than 4 million prescriptions.^[30][31] It is on the World Health Organization's List of Essential Medicines.^[32]