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.
Bicalutamide, sold under the brand name Casodex among others, is an antiandrogen medication that is primarily used to treat prostate cancer. It is typically used together with a gonadotropin-releasing hormone (GnRH) analogue or surgical removal of the testicles to treat advanced prostate cancer. To a lesser extent, it is used for early prostate cancer at a higher dosage as a monotherapy. Bicalutamide is also used to treat excessive hair growth in women, as a component of feminizing hormone therapy for transgender women, to treat early puberty in boys, and to prevent overly long-lasting erections in men. It is taken by mouth.
Flutamide, sold under the brand name Eulexin among others, is a nonsteroidal antiandrogen (NSAA) which is used primarily to treat prostate cancer. It is also used in the treatment of androgen-dependent conditions like acne, excessive hair growth, and high androgen levels in women. It is taken by mouth, usually three times per day.
Nilutamide, sold under the brand names Nilandron and Anandron, is a nonsteroidal antiandrogen (NSAA) which is used in the treatment of prostate cancer. It has also been studied as a component of feminizing hormone therapy for transgender women and to treat acne and seborrhea in women. It is taken by mouth.
Enzalutamide, sold under the brand name Xtandi, is a nonsteroidal antiandrogen (NSAA) medication which is used in the treatment of prostate cancer. It is indicated for use in conjunction with castration in the treatment of metastatic castration-resistant prostate cancer (mCRPC), nonmetastatic castration-resistant prostate cancer, and metastatic castration-sensitive prostate cancer (mCSPC). It is taken by mouth.
This article is about the discovery and development of antiandrogens, or androgen receptor (AR) antagonists.
RU-58642 is a nonsteroidal antiandrogen (NSAA) derived from nilutamide with very high affinity and selectivity for the androgen receptor (AR), which made it among the most potent and efficacious antiandrogens known at the time of its discovery. It was investigated for topical application for the treatment of androgenetic alopecia, but development did not proceed past initial trial stages, and it is now only used for scientific research into the AR.
Hydroxyflutamide (HF, OHF) (developmental code name SCH-16423), or 2-hydroxyflutamide, is a nonsteroidal antiandrogen (NSAA) and the major active metabolite of flutamide, which is considered to be a prodrug of hydroxyflutamide as the active form. It has been reported to possess an IC50 of 700 nM for the androgen receptor (AR), which is about 4-fold less than that of bicalutamide.
RU-58841, also known as PSK-3841 or HMR-3841, is a nonsteroidal antiandrogen (NSAA) which was initially developed in the 1980s by Roussel Uclaf, the French pharmaceutical company from which it received its name. It was formerly under investigation by ProStrakan for potential use as a topical treatment for androgen-dependent conditions including acne, pattern hair loss, and excessive hair growth. The compound is similar in structure to the NSAA RU-58642 but contains a different side-chain. These compounds are similar in chemical structure to nilutamide, which is related to flutamide, bicalutamide, and enzalutamide, all of which are NSAAs similarly. RU-58841 can be synthesized either by building the hydantoin moiety or by aryl coupling to 5,5-dimethylhydantoin.
A nonsteroidal antiandrogen (NSAA) is an antiandrogen with a nonsteroidal chemical structure. They are typically selective and full or silent antagonists of the androgen receptor (AR) and act by directly blocking the effects of androgens like testosterone and dihydrotestosterone (DHT). NSAAs are used in the treatment of androgen-dependent conditions in men and women. They are the converse of steroidal antiandrogens (SAAs), which are antiandrogens that are steroids and are structurally related to testosterone.
Topilutamide, known more commonly as fluridil and sold under the brand name Eucapil, is an antiandrogen medication which is used in the treatment of pattern hair loss in men and women. It is used as a topical medication and is applied to the scalp. Topilutamide belongs to a class of molecules known as perfluoroacylamido-arylpropanamides.
Apalutamide, sold under the brand name Erleada among others, is a nonsteroidal antiandrogen (NSAA) medication which is used in the treatment of prostate cancer. It is specifically indicated for use in conjunction with castration in the treatment of non-metastatic castration-resistant prostate cancer (NM-CRPC). It is taken by mouth.
DIMP, or N-(3,5-dimethyl-4-isoxazolylmethyl)phthalimide, is a nonsteroidal antiandrogen (NSAA) structurally related to thalidomide that was first described in 1973 and was never marketed. Along with flutamide, it was one of the earliest NSAAs to be discovered, and for this reason, has been described as a "classical" NSAA. The drug is a selective, competitive, silent antagonist of the AR, although it is described as an "only relatively weak competitor". Its relative binding affinity for the androgen receptor is about 2.6% of that of metribolone. DIMP possesses no androgenic, estrogenic, progestogenic, or antigonadotropic activity, but it does reverse the antigonadotropic effects of testosterone, indicating that, like other pure AR antagonists, it is progonadotropic.
Trimethyltrienolone (TMT), also known by its developmental code name R-2956 or RU-2956, is an antiandrogen medication which was never introduced for medical use but has been used in scientific research.
AA560 is an orally active nonsteroidal antiandrogen (NSAA) that was developed in Japan and was first described in the literature in 1977 but was never marketed. It is an anilide derivative and analogue of the NSAA flutamide, and shows greater in vivo antiandrogenic potency than does flutamide. Similarly to flutamide, AA560 is a selective antagonist of the androgen receptor (AR) and consequently shows progonadotropic effects by increasing levels of gonadotropins and testosterone via disinhibition of the hypothalamic-pituitary-gonadal axis.
LG-120907 is a nonsteroidal antiandrogen (NSAA) of the quinoline group which was developed by Ligand Pharmaceuticals along with selective androgen receptor modulators (SARMs) like LG-121071 and was never marketed. The drug is a high-affinity antagonist of the androgen receptor (AR) with a Ki value of 26 nM and has been found to inhibit growth of the ventral prostate and seminal vesicles in male rats without increasing circulating levels of luteinizing hormone or testosterone. However, this tissue selectivity has not been assessed in humans. LG-120907 is orally active and shows greater oral potency than the arylpropionamide NSAA flutamide.
The medical uses of bicalutamide, a nonsteroidal antiandrogen (NSAA), include the treatment of androgen-dependent conditions and hormone therapy to block the effects of androgens. Such indications include the treatment of prostate cancer in men, skin and hair conditions such as acne, seborrhea, hirsutism, and pattern hair loss in women, high testosterone levels in women, hormone therapy in transgender women, as a puberty blocker to prevent puberty in transgender girls and to treat early puberty in boys, and the treatment of long-lasting erections in men. It may also have some value in the treatment of paraphilias and hypersexuality in men.
Comparison of the nonsteroidal antiandrogen (NSAA) bicalutamide with other antiandrogens reveals differences between the medications in terms of efficacy, tolerability, safety, and other parameters. Relative to the other first-generation NSAAs, flutamide and nilutamide, bicalutamide shows improved potency, efficacy, tolerability, and safety, and has largely replaced these medications in clinical practice. Compared to the second-generation NSAAs, enzalutamide and apalutamide, bicalutamide has inferior potency and efficacy but similar tolerability and safety and a lower propensity for drug interactions.
RD-162 is a second-generation nonsteroidal antiandrogen (NSAA) which was developed for the treatment of prostate cancer but was never marketed. It acts as a potent and selective silent antagonist of the androgen receptor (AR). The drug is a diarylthiohydantoin derivative. It is closely related to enzalutamide and apalutamide. Both RD-162 and enzalutamide show 5- to 8-fold higher affinity for the AR than the first-generation NSAA bicalutamide, and only 2- to 3-fold lower affinity than dihydrotestosterone (DHT), the major endogenous ligand of the receptor in the prostate gland.
RU-59063 is a nonsteroidal androgen or selective androgen receptor modulator (SARM) which was first described in 1994 and was never marketed. It was originally thought to be a potent antiandrogen, but subsequent research found that it actually possesses dose-dependent androgenic activity, albeit with lower efficacy than dihydrotestosterone (DHT). The drug is an N-substituted arylthiohydantoin and was derived from the first-generation nonsteroidal antiandrogen (NSAA) nilutamide. The second-generation NSAAs enzalutamide, RD-162, and apalutamide were derived from RU-59063.
