This is due to steric hindrance of C17β-position metabolism during the first-pass through the liver. In contrast, most AAS that are not 17α-alkylated, like nandrolone, are not active orally, and must instead be administered via intramuscular injection. This is almost always in ester form; for instance, in the case of nandrolone, as nandrolone decanoate or nandrolone phenylpropionate. History
Testosterone was first isolated and synthesized in 1935. Shortly thereafter, in 1937, testosterone first became commercially available as a pharmaceutical drug in the form of pellets and then in ester form for intramuscular injection as the relatively short-acting testosterone propionate. Methyltestosterone, one of the first synthetic AAS and orally active androgens, was introduced in 1935, but was associated with hepatotoxicity and eventually became largely medically obsolete. In the mid-1950s, the longer-acting testosterone esters testosterone enanthate and testosterone cypionate were introduced. They largely superseded testosterone propionate and became the major testosterone esters used medically for over half a century. In the 1970s, testosterone undecanoate was introduced for oral use in Europe, although intramuscular testosterone undecanoate had already been in use in China for several years. Intramuscular testosterone undecanoate was not introduced in Europe and the United States until much later (in the early to mid 2000s and 2014, respectively).The history of testosterone as a medication has been reviewed. Society and culture
Usage
In the US in the 2000s, companies and figures in the popular media have heavily marketed notions of "andropause" as something parallel to menopause; these notions have been rejected by the medical community.
Availability
United States
As of November 2016, unmodified (non-esterified) testosterone is available in the United States in the following formulations:
Topical gels: AndroGel, Fortesta, Testim, Testosterone (generic)
Topical solutions: Axiron, Testosterone (generic)
Transdermal patches: Androderm, Testoderm (discontinued), Testoderm TTS (discontinued), Testosterone (generic)
Intranasal gels: Natesto
Buccal tablets: Striant
Pellet implants: TestopelAnd the following ester prodrugs of testosterone are available in the United States in oil solutions for intramuscular injection:
Testosterone cypionate: Depo-Testosterone, Testosterone Cypionate (generic)
Testosterone enanthate: Delatestryl, Xyosted (auto-injector), Testosterone Enanthate (generic)
Testosterone propionate: Testosterone Propionate (generic)
Testosterone undecanoate: AveedUnmodified testosterone was also formerly available for intramuscular injection but was discontinued.Testosterone cypionate and testosterone enanthate were formerly available in combination with estradiol cypionate and estradiol valerate, respectively, under the brand names Depo-Testadiol and Ditate-DS, respectively, as oil solutions for intramuscular injection, but these formulations have been discontinued.Unlike in Europe, Canada, and much of the rest of the world, oral testosterone undecanoate is not available in the United States. Canada
As of November 2016, testosterone is available in Canada in the form of topical gels (AndroGel, Testim), topical solutions (Axiron), transdermal patches (Androderm), and intranasal gels (Natesto). Testosterone cypionate (Depo-Testosterone, Testosterone Cypionate (generic)), testosterone enanthate (Delatestryl, PMS-Testosterone Enanthate), and testosterone propionate (Testosterone Propionate (generic)) are available as oil solutions for intramuscular injection and testosterone undecanoate (Andriol, PMS-Testosterone, Taro-Testosterone) is available in the form of oral capsules. Testosterone buccal tablets and pellet implants do not appear to be available in Canada. Other countries
Testosterone and/or its esters are widely available in countries throughout the world in a variety of formulations.