Tetrahydrogestrinone is an anabolic steroid

Anabolic steroid

Anabolic steroids, technically known as anabolic-androgen steroids or colloquially simply as "steroids", are drugs that mimic the effects of testosterone and dihydrotestosterone in the body. They increase protein synthesis within cells, which results in the buildup of cellular tissue ,...

 developed by Patrick Arnold

Patrick Arnold

Patrick Arnold is an American organic chemist responsible for creating the designer steroid tetrahydrogestrinone, also known as THG and "the clear". THG, along with two other anabolic steroids that Patrick Arnold manufactured , were drugs at the heart of the BALCO scandal...

. It has affinity to the androgen receptor

Androgen receptor

The androgen receptor , also known as NR3C4 , is a type of nuclear receptor that is activated by binding of either of the androgenic hormones testosterone or dihydrotestosterone in the cytoplasm and then translocating into the nucleus...

 and the progesterone receptor

Progesterone receptor

The progesterone receptor also known as NR3C3 , is an intracellular steroid receptor that specifically binds progesterone...

, but not to the estrogen receptor. The drug has been considered a designer drug

Designer drug

Designer drug is a term used to describe drugs that are created to get around existing drug laws, usually by preparing analogs or derivatives of existing drugs by modifying their chemical structure to varying degrees, or less commonly by finding drugs with entirely different chemical structures...

, closely related to the banned anabolic steroids gestrinone

Gestrinone

Gestrinone is a synthetic steroid hormone that acts as an anti-progestin and also has some androgenic activity. It is marketed under the names Dimetriose, Dimetrose, and Nemestran, as a treatment for endometriosis. Gestrinone is available in many countries, but not in the USA...

 and trenbolone

Trenbolone

Trenbolone is a steroid used by veterinarians on livestock to increase muscle growth and appetite. To increase its effective half-life, trenbolone is not used in an unrefined form, but is rather administered as ester derivatives such as trenbolone acetate, trenbolone enanthate or trenbolone...

, and was referred to as an unapproved new drug by the Food and Drug Administration

Food and Drug Administration

The Food and Drug Administration is an agency of the United States Department of Health and Human Services, one of the United States federal executive departments...

 (FDA) in 2003 before the subsequent scheduling of it in 2005.
Structure-activity relationship

Structure-activity relationship

The structure–activity relationship is the relationship between the chemical or 3D structure of a molecule and its biological activity. The analysis of SAR enables the determination of the chemical groups responsible for evoking a target biological effect in the organism...

 studies report that the potency of the drug is outstanding, surpassing, on a milligram per milligram basis, every known synthesized or commercial available anabolic steroid

Anabolic steroid

Anabolic steroids, technically known as anabolic-androgen steroids or colloquially simply as "steroids", are drugs that mimic the effects of testosterone and dihydrotestosterone in the body. They increase protein synthesis within cells, which results in the buildup of cellular tissue ,...

 at the time of its development.