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.
Selective androgen receptor modulators (SARMs) are a class of androgen receptor ligands that were developed with the intention of maintaining some of the desirable effects of androgens, such as improving bone density and increasing lean body mass, with a much lower risk of androgenic side effects than alternative therapies such as testosterone.
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.
BMS-564,929 is an investigational selective androgen receptor modulator (SARM) which is being developed by Bristol-Myers Squibb for treatment of the symptoms of age-related decline in androgen levels in men ("andropause"). These symptoms may include depression, loss of muscle mass and strength, reduction in libido and osteoporosis. Treatment with exogenous testosterone is effective in counteracting these symptoms but is associated with a range of side effects, the most serious of which is enlargement of the prostate gland, which can lead to benign prostatic hypertrophy and even prostate cancer. This means there is a clinical need for selective androgen receptor modulators, which produce anabolic effects in some tissues such as muscle and bone, but without stimulating androgen receptors in the prostate.
S-40503 is an investigational selective androgen receptor modulator (SARM) developed by the Japanese company Kaken Pharmaceuticals, which was developed for the treatment of osteoporosis. SARMs are a new class of drugs which produce tissue-specific anabolic effects in some tissues such as muscle and bone, but without stimulating androgen receptors in other tissues such as in the prostate gland, thus avoiding side effects such as benign prostatic hypertrophy which can occur following treatment with unselective androgens like testosterone or anabolic steroids.
LGD-2226 is an investigational selective androgen receptor modulator (SARM), which is being developed for treatment of muscle wasting and osteoporosis.
Enobosarm, also known as ostarine or MK-2866, is a selective androgen receptor modulator (SARM) developed by GTx, Inc. for the treatment of conditions such as muscle wasting, osteoporosis, and breast cancer, formerly under development by Merck & Company. Enobosarm is the most well-studied SARM. According to GTx, 25 studies have been carried out on more than 1,700 humans as of 2020 involving doses from 1 to 18 mg each day.
Andarine is an investigational selective androgen receptor modulator (SARM) developed by GTX, Inc for treatment of conditions such as muscle wasting, osteoporosis and benign prostatic hypertrophy (BPH), using the nonsteroidal antiandrogen bicalutamide as a lead compound.
The first antiandrogen was discovered in the 1960s. Antiandrogens antagonise the androgen receptor (AR) and thereby block the biological effects of testosterone and dihydrotestosterone (DHT). Antiandrogens are important for men with hormonally responsive diseases like prostate cancer, benign prostatic hyperplasia (BHP), acne, seborrhea, hirsutism and androgen alopecia. Antiandrogens are mainly used for the treatment of prostate diseases. Research from 2010 suggests that ARs could be linked to the disease progression of triple-negative breast cancer and salivary duct carcinoma and that antiandrogens can potentially be used to treat it.
Oxendolone, sold under the brand names Prostetin and Roxenone, is an antiandrogen and progestin medication which is used in Japan in the treatment of enlarged prostate. However, this use is controversial due to concerns about its clinical efficacy. Oxendolone is not effective by mouth and must be given by injection into muscle.
RAD140 is an investigational selective androgen receptor modulator (SARM) that is developed by Radius Health, Inc. for use in androgen replacement therapy. It was licensed to Ellipses Pharmaceuticals in 2020. Some of the potential benefits under investigation are for the treatment of conditions such as muscle wasting and bone loss.
LG121071 is a selective androgen receptor modulator (SARM) developed by Ligand Pharmaceuticals that was first described in 1999 and was the first orally active nonsteroidal androgen to be discovered. It is a tricyclic quinolone derivative, structurally distinct from other nonsteroidal AR agonists like andarine and enobosarm (ostarine). The drug acts as a high-affinity full agonist of the androgen receptor (AR), with a potency and efficacy that is said to be equivalent to that of dihydrotestosterone (DHT). Unlike testosterone, but similarly to DHT, LG121071 and other nonsteroidal androgens cannot be potentiated by 5α-reductase in androgenic tissues, and for this reason, show tissue-selective androgenic effects. In accordance, they are said to possess full anabolic activity with reduced androgenic activity, similarly to anabolic-androgenic steroids.
MK-0773, also known as PF-05314882, is a steroidal, orally active selective androgen receptor modulator (SARM) that was under development by Merck and GTx for the treatment of sarcopenia in women and men. Clinical trials for sarcopenia began in late 2007 but the collaboration between Merck and GTx ended in early 2010 and GTx terminated development of MK-0773 shortly thereafter.
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.
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.
EM-5854 is a steroidal antiandrogen which was under development by Endoceutics, Inc. for the treatment of prostate cancer. It was first described in a patent in 2008, and was further characterized in 2012. EM-5854 reached phase I/II clinical trials for the treatment of prostate cancer but development was discontinued in March 2019.
OPK-88004 is a non-steroidal indole derivative which acts as a selective androgen receptor modulator (SARM). It has been investigated by OPKO Health for the treatment of erectile dysfunction and symptoms associated with benign prostate hyperplasia.
GLPG-0492 (DT-200) is a drug which acts as a selective androgen receptor modulator (SARM). It has been investigated for the treatment of cachexia and muscular dystrophy.
LY305 is a transdermally bioavailable selective androgen receptor modulator (SARM) developed by Eli Lilly for the treatment of osteoporosis in men. Its chemical structure includes N-arylhydroxyalkyl. A phase one trial found promising results.
