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.
An androgen is any natural or synthetic steroid hormone that regulates the development and maintenance of male characteristics in vertebrates by binding to androgen receptors. This includes the embryological development of the primary male sex organs, and the development of male secondary sex characteristics at puberty. Androgens are synthesized in the testes, the ovaries, and the adrenal glands.
Selective androgen receptor modulators (SARMs) are a class of drugs that selectively activate the androgen receptor in specific tissues, promoting muscle and bone growth while having less effect on male reproductive tissues like the prostate gland.
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.
Enobosarm, also formerly known as ostarine and by the developmental code names GTx-024, MK-2866, and S-22, is a selective androgen receptor modulator (SARM) which is under development for the treatment of androgen receptor-positive breast cancer in women and for improvement of body composition in people taking GLP-1 receptor agonists like semaglutide. It was also under development for a variety of other indications, including treatment of cachexia, Duchenne muscular dystrophy, muscle atrophy or sarcopenia, and stress urinary incontinence, but development for all other uses has been discontinued. Enobosarm was evaluated for the treatment of muscle wasting related to cancer in late-stage clinical trials, and the drug improved lean body mass in these trials, but it was not effective in improving muscle strength. As a result, enobosarm was not approved and development for this use was terminated. Enobosarm is taken by mouth.
Andarine is a selective androgen receptor modulator (SARM) which was developed by GTX, Inc for the treatment of conditions such as muscle wasting, osteoporosis, and benign prostatic hypertrophy (BPH), using the nonsteroidal antiandrogen bicalutamide as a lead compound. Development of andarine for all indications has been discontinued, in favor of the structurally related and improved compound enobosarm.
AC-262536 is a drug developed by Acadia Pharmaceuticals which acts as a selective androgen receptor modulator (SARM). Chemically it possesses endo-exo isomerism, with the endo form being the active form. It acts as a partial agonist for the androgen receptor with a Ki of 5 nM, and no significant affinity for any other receptors tested. In animal studies it produced a maximal effect of around 66% of the levator ani muscle weight increase of testosterone, but only around 27% of its maximal effect on prostate gland weight. It is an aniline SARM related to ACP-105 and vosilasarm (RAD140).
3β-Androstanediol, also known as 5α-androstane-3β,17β-diol, and sometimes shortened in the literature to 3β-diol, is an endogenous steroid hormone and a metabolite of androgens like dehydroepiandrosterone (DHEA) and dihydrotestosterone (DHT).
Vosilasarm, also known by the development codes RAD140 and EP0062 and by the black-market name Testolone or Testalone, is a selective androgen receptor modulator (SARM) which is under development for the treatment of hormone-sensitive breast cancer. It is specifically under development for the treatment of androgen receptor-positive, estrogen receptor-negative, HER2-negative advanced breast cancer. Vosilasarm was also previously under development for the treatment of sarcopenia, osteoporosis, and weight loss due to cancer cachexia, but development for these indications was discontinued. The drug is taken by mouth.
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 pharmacology of bicalutamide is the study of the pharmacodynamic and pharmacokinetic properties of the nonsteroidal antiandrogen (NSAA) bicalutamide. In terms of pharmacodynamics, bicalutamide acts as a selective antagonist of the androgen receptor (AR), the biological target of androgens like testosterone and dihydrotestosterone (DHT). It has no capacity to activate the AR. It does not decrease androgen levels and has no other important hormonal activity. The medication has progonadotropic effects due to its AR antagonist activity and can increase androgen, estrogen, and neurosteroid production and levels. This results in a variety of differences of bicalutamide monotherapy compared to surgical and medical castration, such as indirect estrogenic effects and associated benefits like preservation of sexual function and drawbacks like gynecomastia. Bicalutamide can paradoxically stimulate late-stage prostate cancer due to accumulated mutations in the cancer. When used as a monotherapy, bicalutamide can induce breast development in males due to its estrogenic effects. Unlike other kinds of antiandrogens, it may have less adverse effect on the testes and fertility.
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.
GSK2881078 is a drug which acts as a selective androgen receptor modulator (SARM). It was developed for the prevention of muscle wasting and sarcopenia in elderly people.
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.
ACP-105 is a drug which acts as a selective androgen receptor modulator (SARM). It has been investigated for potential use in the treatment of age-related cognitive decline. The drug has been found to reduce anxiety-like behavior in a mouse model of Alzheimer's disease when administered alone, as well as enhance spatial memory when coadministered with the selective estrogen receptor β agonist AC-186. ACP-105 is an aniline SARM and is related to AC-262536 and vosilasarm (RAD140).
PF-06260414 is a drug which acts as a selective androgen receptor modulator (SARM), and was developed for androgen replacement therapy.
GSK4336A is a drug which acts as a selective androgen receptor modulator (SARM), and was developed for androgen replacement therapy.
Arcarine (ORM-11984) is a selective androgen receptor modulator (SARM) developed by Orion Corporation, a Finnish pharmaceutical company. It belongs to a class of drugs designed to have tissue-selective androgenic effects, potentially offering the benefits of androgens while minimizing unwanted side effects. Arcarine was investigated for the treatment of various conditions, including benign prostatic hyperplasia, hypogonadism, and osteoporosis. The compound reached Phase I clinical trials before development was discontinued. Like other SARMs, Arcarine was developed to potentially provide anabolic effects in muscle and bone tissue while having reduced androgenic effects in other tissues, such as the prostate.
JNJ-37654032 is a selective androgen receptor modulator (SARM) which was developed by Johnson & Johnson for the potential treatment of muscular atrophy but was never marketed.
JNJ-26146900 is a selective androgen receptor modulator (SARM) which was developed by Johnson & Johnson for the potential treatment of prostate cancer but was never marketed.
