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.
Raloxifene, sold under the brand name Evista among others, is a medication used to prevent and treat osteoporosis in postmenopausal women and those on glucocorticoids. For osteoporosis it is less preferred than bisphosphonates. It is also used to reduce the risk of breast cancer in those at high risk. It is taken by mouth.
Sarcopenia is a type of muscle loss that occurs with aging and/or immobility. It is characterized by the degenerative loss of skeletal muscle mass, quality, and strength. The rate of muscle loss is dependent on exercise level, co-morbidities, nutrition and other factors. The muscle loss is related to changes in muscle synthesis signalling pathways. It is distinct from cachexia, in which muscle is degraded through cytokine-mediated degradation, although both conditions may co-exist. Sarcopenia is considered a component of frailty syndrome. Sarcopenia can lead to reduced quality of life, falls, fracture, and disability.
Selective androgen receptor modulators (SARMs) are a class of drugs that selectively activate the androgen receptor in certain tissues like muscle and bone over other tissues like the prostate gland and seminal vesicles.
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 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. 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.
Ligandrol, also known by the developmental code names VK5211 and LGD-4033, is a selective androgen receptor modulator (SARM) which is under development for the treatment of muscle atrophy in people with hip fracture. It was also under development for the treatment of cachexia, hypogonadism, and osteoporosis, but development for these indications was discontinued. Ligandrol has been reported to dose-dependently improve lean body mass and muscle strength in preliminary clinical trials, but is still being developed and has not been approved for medical use. The drug is taken by mouth.
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.
Acetothiolutamide is a selective androgen receptor modulator (SARM) derived from the nonsteroidal antiandrogen bicalutamide that was described in 2002 and was one of the first SARMs to be discovered and developed. It is a high-affinity, selective ligand of the androgen receptor (AR), where it acts as a full agonist in vitro, and has in vitro potency comparable to that of testosterone. However, in vivo, acetothiolutamide displayed overall negligible androgenic effects, though significant anabolic effects were observed at high doses. In addition, notable antiandrogen effects were observed in castrated male rats treated with testosterone propionate. The discrepancy between the in vitro and in vivo actions of acetothiolutamide was determined to be related to rapid plasma clearance and extensive hepatic metabolism into a variety of metabolites with differing pharmacological activity, including AR partial agonism and antagonism. In accordance with its poor metabolic stability, acetothiolutamide is not orally bioavailable, and shows activity only via injected routes such as subcutaneous and intravenous.
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. MK-0773 was developed as a more advanced version of the related compound TFM-4AS-1.
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.
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.
PF-06260414 is a drug which acts as a selective androgen receptor modulator (SARM), and was developed for androgen replacement therapy.
Mevidalen (developmental code name LY-3154207) is a dopaminergic drug which is under development for the treatment of Lewy body disease, including those with Parkinson's disease. It acts as a selective positive allosteric modulator (PAM) of the dopamine D1 receptor. The drug is orally active and crosses the blood–brain barrier. It is a tetrahydroisoquinoline and is a close analogue of DETQ, another D1 receptor PAM. Mevidalen has been found to have wakefulness-promoting effects in sleep-deprived humans. Side effects of mevidalen have been reported to include increased heart rate and blood pressure, insomnia, dizziness, nausea, vomiting, anxiety, nervousness, fatigue, headaches, palpitations, and contact dermatitis, as well as falls in those with dementia. As of March 2022, mevidalen is in phase 2 clinical trials for the treatment of Lewy body disease. Besides for movement disorders and dementia, D1 receptor PAMs like mevidalen might have value in the treatment of certain neuropsychiatric disorders, such as depression, excessive somnolence, and attention deficit hyperactivity disorder.
Compound 2f (SARM) is a drug which acts as a selective androgen receptor modulator (SARM), originally developed by Takeda Pharmaceutical for the treatment of prostate cancer. It is a potent but tissue specific androgen agonist with an EC50 of 4.7nM, producing anabolic effects on muscles and in the central nervous system but with little effect on the prostate gland, and inducing sexual behaviour in animal studies.
