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.
Stanozolol, sold under many brand names, is an androgen and anabolic steroid (AAS) medication derived from dihydrotestosterone (DHT). It is used to treat hereditary angioedema. It was developed by American pharmaceutical company Winthrop Laboratories in 1962, and has been approved by the U.S. Food and Drug Administration for human use, though it is no longer marketed in the USA. It is also used in veterinary medicine. Stanozolol has mostly been discontinued, and remains available in only a few countries. It is given by mouth in humans or by injection into muscle in animals.
Nandrolone decanoate, sold under the brand name Deca-Durabolin among others, is an androgen and anabolic steroid (AAS) medication which is used primarily in the treatment of anemias and wasting syndromes, as well as osteoporosis in menopausal women. It is given by injection into muscle or fat once every one to four weeks.
Selective Androgen Receptor Modulators or SARMs are a class of androgen receptor ligands that maintain some of the desirable effects of androgens, such as preventing osteoporsis and muscle loss while reducing risks of developing prostate cancer. In the last 1990s, the first nonsteroidal SARM, an analog of bicalutamide, was discovered. They are intended to have the same kind of effects as androgenic drugs, such as anabolic-androgenic steroids, but be more selective in their action. As of early 2020, there are no SARMs which have been approved for therapeutic use by the U.S Food and Drug Administration.
Desoxymethyltestosterone (DMT), known by the nicknames Madol and Pheraplex, is a synthetic and orally active anabolic–androgenic steroid (AAS) and a 17α-methylated derivative of dihydrotestosterone (DHT) which was never marketed for medical use. It was one of the first designer steroids to be marketed as a performance-enhancing drug to athletes and bodybuilders.
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.
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 an investigational selective androgen receptor modulator (SARM) developed by GTx, Inc. for the treatment of conditions such as muscle wasting and osteoporosis, formerly under development by Merck & Company.
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, using the nonsteroidal antiandrogen bicalutamide as a lead compound.
1-Testosterone, also known as δ1-dihydrotestosterone (δ1-DHT), as well as dihydroboldenone, is a synthetic anabolic–androgenic steroid (AAS) and a 5α-reduced derivative of boldenone (Δ1-testosterone). It differs from testosterone by having a 1(2)-double bond instead of a 4(5)-double bond in its A ring. It was legally sold online in the United States until 2005, when it was reclassified as a Schedule III drug.
Bolandione, also known as 19-norandrostenedione, as well as 19-norandrost-4-en-3,17-dione or estr-4-ene-3,17-dione, is a precursor of the anabolic-androgenic steroid (AAS) nandrolone (19-nortestosterone). Until 2005, bolandione was available without prescription in United States, where it was marketed as a prohormone, but it is now classified as a Schedule III drug. It is also banned from use in many sports, including the Olympic Games, under the World Anti-Doping Code. Bolandione is readily metabolized to nandrolone after oral administration, but its potency to transactivate the androgen receptor dependent reporter gene expression is 10 times lower as compared to dihydrotestosterone (DHT).
LGD-3303 is a drug which acts as a selective androgen receptor modulator (SARM), with good oral bioavailability. It is a selective agonist for the androgen receptor, producing functional selectivity with effective dissociation of anabolic and androgenic effects, acting as a partial agonist for androgenic effects, but a full agonist for anabolic effects. It has been investigated as a possible treatment for osteoporosis, and was shown in animal studies to enhance the effectiveness of a bisphosphonate drug.
Ligandrol is a novel nonsteroidal oral selective androgen receptor modulator (SARM) for treatment of conditions such as muscle wasting and osteoporosis, discovered by Ligand Pharmaceuticals and under development by Viking Therapeutics.
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.
Nandrolone phenylpropionate (NPP), or nandrolone phenpropionate, sold under the brand name Durabolin among others, is an androgen and anabolic steroid (AAS) medication which has been used primarily in the treatment of breast cancer and osteoporosis in women. It is given by injection into muscle once every week. Although it was widely used in the past, the drug has mostly been discontinued and hence is now mostly no longer available.
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.
TFM-4AS-1 is a dual selective androgen receptor modulator (SARM) and 5α-reductase inhibitor. It is a potent and selective partial agonist (Emax = 55%) of the androgen receptor (IC50 = 30 nM) and inhibitor of 5α-reductase types I and II (IC50 = 2 and 3 nM, respectively). TFM-4AS-1 shows tissue-selective androgenic effects; it promotes the accumulation of bone and muscle mass and has reduced effects in reproductive tissues and sebaceous glands. In addition, it does not promote growth of the prostate gland and it antagonizes the actions of dihydrotestosterone (DHT) in the seminal vesicles. Structurally, TFM-4AS-1 is a 4-azasteroid.
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.
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