Dean Destructo
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Tetrahydrogestrinone[SUP][pronunciation?][/SUP][SUP][1][/SUP](often referred to as THG or The Clear) is an anabolic steroid developed by Patrick Arnold.[SUP][2][/SUP] It has affinity to the androgen receptor and the progesterone receptor, but not to the estrogen receptor.[SUP][3][/SUP]
Developed completely in secret by Patrick Arnold, the drug was used in performance enhancement without having been studied for side-effects. The drug has been considered a designer drug, closely related to the banned anabolic steroids gestrinone and trenbolone,[SUP][4][/SUP]and was referred to as an unapproved new drug by the Food and Drug Administration(FDA) in 2003 before the subsequent scheduling of it in 2005. A synthesis was devised to ensure a source of material for comparison.[SUP][5][/SUP] The drug has never entered legitimate medical use, although some studies have been made of its properties and toxicity. Concerns have also been raised about its potential use in horse-racing and other veterinary contexts.
Structure-activity relationship studies report that the potency of the drug is outstanding, surpassing, on a milligram per milligram basis, every known synthesized or commercially available anabolic steroid at the time of its development. It is a highly potent agonist for the androgen and progesterone receptors,[SUP][6][/SUP] around 10 times more potent than the comparison drugs nandrolone or trenbolone, but with no estrogenic activity. It has been found to bind to the androgen receptor with similar affinity to dihydrotestosterone and produces growth of muscle tissue.[SUP][7][/SUP] According to Patrick Arnold, due to the drug's potency, he never had to supply significant quantities to BALCO, because "just a couple of drops under the tongue" were a sufficient dose.[SUP][2]
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When THG reaches the nucleus of a cell, it binds to the androgen receptor at the ligand-binding pocket. Here it changes the expression of a variety of genes, turning on several anabolic and androgenic functions.[SUP][8][/SUP]
It is the ligand’s structure which determines the number of interactions that can take place with the human androgen receptor ligand-binding domain. Even minor modifications in the ligand's structure have a great impact on the strength of the interactions this ligand has with the androgen receptor. THG, possessing a high affinity, establishes more van der Waals contacts with the receptor than with many other steroids. It is this higher affinity and specific geometry of THG which makes these interactions with the Androgen Receptor so strong, resulting in THG’s potency.[SUP][9][/SUP]
