Antiandrogens, also known as androgen antagonists or testosterone blockers, are a class of drugs that prevent androgens like testosterone and dihydrotestosterone (DHT) from mediating their biological effects in the body. They act by blocking the androgen receptor (AR) and/or inhibiting or suppressing androgen production. They can be thought of as the functional opposites of AR agonists, for instance androgens and anabolic steroids (AAS) like testosterone, DHT, and nandrolone and selective androgen receptor modulators (SARMs) like enobosarm. Antiandrogens are one of three types of sex hormone antagonists, the others being antiestrogens and antiprogestogens.
Progestogen-only pills or progestin-only pills (POP) are contraceptive pills that contain only synthetic progestogens (progestins) and do not contain estrogen. They are colloquially known as mini pills.
Medroxyprogesterone (MP), is a progestin which is not used medically. A derivative, medroxyprogesterone acetate (MPA), is used as a medication in humans, and is far more widely known in comparison. Medroxyprogesterone is sometimes used as a synonym for medroxyprogesterone acetate, and what is almost always being referred to when the term is used is MPA and not medroxyprogesterone.
Chlormadinone acetate (CMA), sold under the brand names Belara, Gynorelle, Lutéran, and Prostal among others, is a progestin and antiandrogen medication which is used in birth control pills to prevent pregnancy, as a component of menopausal hormone therapy, in the treatment of gynecological disorders, and in the treatment of androgen-dependent conditions like enlarged prostate and prostate cancer in men and acne and hirsutism in women. It is available both at a low dose in combination with an estrogen in birth control pills and, in a few countries like France and Japan, at low, moderate, and high doses alone for various indications. It is taken by mouth.
Melengestrol acetate (MLGA), sold under the brand names Heifermax and MGA among others, is a progestin medication which is used in animal reproduction. It is not approved for use in humans, and is instead used as an implantable contraceptive for captive animals in zoos and other refuges, and is also used as a feed additive to promote growth in cattle, a purpose it is licensed for in the United States and Canada.
Allylestrenol, sold under the brand names Gestanin and Turinal among others, is a progestin medication which is used to treat recurrent and threatened miscarriage and to prevent premature labor in pregnant women. However, except in the case of proven progesterone deficiency, its use for such purposes is no longer recommended. It is also used in Japan to treat benign prostatic hyperplasia (BPH) in men. The medication is used alone and is not formulated in combination with an estrogen. It is taken by mouth.
An antigonadotropin is a drug which suppresses the activity and/or downstream effects of one or both of the gonadotropins, follicle-stimulating hormone (FSH) and luteinizing hormone (LH). This results in an inhibition of the hypothalamic-pituitary-gonadal (HPG) axis, and thus a decrease in the levels of the androgen, estrogen, and progestogen sex steroids in the body. Antigonadotropins also inhibit ovulation in women and spermatogenesis in men. They are used for a variety of purposes, including for the hormonal birth control, treatment of hormonally-sensitive cancers, to delay precocious puberty and puberty in transgender youth, as a form of chemical castration to reduce the sex drives of individuals with hypersexuality or pedophilia, and to treat estrogen-associated conditions in women such as menorrhagia and endometriosis, among others. High-dose antigonadotropin therapy has been referred to as medical castration.
Cyproterone acetate (CPA), sold alone under the brand name Androcur or with ethinylestradiol under the brand names Diane or Diane-35 among others, is an antiandrogen and progestin medication which is used in the treatment of androgen-dependent conditions like acne, excessive hair growth, early puberty, and prostate cancer, as a component of feminizing hormone therapy for transgender women, and in birth control pills. It is formulated and used both alone and in combination with an estrogen and is available for use both by mouth and by injection into muscle. CPA is taken by mouth one to three times per day or given by injection once or twice per week.
Delmadinone acetate (DMA), sold under the brand name Tardak among others, is a progestin and antiandrogen which is used in veterinary medicine to treat androgen-dependent conditions such as benign prostatic hyperplasia. It must be used with care as it has the potential to cause adrenal insufficiency via inhibition of adrenocorticotropic hormone (ACTH) secretion from the pituitary gland. DMA is the C17α acetate ester of delmadinone, which, in contrast to DMA, was never marketed for medical use.
Osaterone acetate, sold under the brand name Ypozane, is a medication which is used in veterinary medicine in Europe in the treatment of enlarged prostate in dogs. It is given by mouth.
Hydroxyprogesterone acetate (OHPA), sold under the brand name Prodox, is an orally active progestin related to hydroxyprogesterone caproate (OHPC) which has been used in clinical and veterinary medicine. It has reportedly also been used in birth control pills.
Anagestone acetate, sold under the brand names Anatropin and Neo-Novum, is a progestin medication which was withdrawn from medical use.
Ethynerone, also known as 17α-(2-chloroethynyl)estra-4,9-dien-17β-ol-3-one, is a steroidal progestin of the 19-nortestosterone group that was first reported in 1961 but was never marketed. Under the developmental code name MK-665, it was studied in combination with mestranol as an oral contraceptive. Development of the drug was discontinued due to concerns surrounding toxicity findings in dogs. It is a chloroethynylated derivative of norethisterone.
Osaterone, also known as 17α-hydroxy-6-chloro-2-oxa-6-dehydroprogesterone, as well as 2-oxachloromadinone, is a steroidal antiandrogen and progestin that was never marketed. The C17α acetate ester of osaterone, osaterone acetate, in contrast, has been marketed.
Flugestone acetate (FGA), sold under the brand name Cronolone among others, is a progestin medication which is used in veterinary medicine.
Edogestrone, or edogesterone, also known as 17α-acetoxy-3,3-ethylenedioxy-6-methylpregn-5-en-20-one, is a steroidal progestin and antiandrogen of the 17α-hydroxyprogesterone group which was synthesized in 1964 but was never marketed. Similarly to the structurally related steroid cyproterone acetate, edogestrone binds directly to the androgen receptor and antagonizes it, displacing androgens like testosterone from the receptor, though not as potently as cyproterone acetate. The drug has also been found to suppress androgen production, likely via progesterone receptor activation-mediated antigonadotropic activity.
Clogestone acetate (USAN), also known as chlormadinol acetate or as 3β,17α-diacetoxy-6-chloropregna-4,6-diene-20-one, is a steroidal progestin which was investigated as a progestin-only contraceptive and postcoital contraceptive but was never marketed. It is the diacetate ester of clogestone, which, similarly was never marketed. Clogestone acetate produces chlormadinone acetate as an active metabolite.
Amadinone (INN), also known as 19-norchlormadinone, is a steroidal progestin of the 19-norprogesterone and 17α-hydroxyprogesterone groups that was synthesized and characterized in 1968 but was never marketed. It has antigonadotropic properties, and for this reason, is a functional antiandrogen. An acetate ester, amadinone acetate, also exists, but similarly was never marketed.
Amadinone acetate (USAN), also known as 19-norchlormadinone acetate, is a steroidal progestin of the 19-norprogesterone and 17α-hydroxyprogesterone groups that was never marketed. It is the acetate ester of amadinone, which, similarly, was never marketed.
