General Information

TESTOSTERONE ENANTHATE INJECTION was the first ever synthesized anabolic steroid. Testosterone enanthate is a slow-acting, long-ester, oil-based injectable testosterone compound that is commonly prescribed for the treatment of hypogonadism – low testosterone levels and various related symptoms in males.

Testosterone enanthate injection first appeared in the U.S. prescription drug market during the early 1950’s, as Delatestryl by Squibb.  It changed hands several times over the years, most notably to Mead Johnson, BTG, Savient, and in December 2005, Indevus.  Testosterone enanthates were most prominently featured in a hybrid blend with testosterone propionate under the brand Testoviron, a drug that has seen uninterrupted production by Schering AG of Germany for more than 50 years.

Testosterone is the primary androgen found in the body. Endogenous testosterone is synthesized by cells in the testis, ovary, and adrenal cortex. Therapeutically, testosterone is used in the management of hypogonadism, either congenital or acquired. Testosterone is also the most effective exogenous androgen for the palliative treatment of carcinoma of the breast in postmenopausal women. Testosterone was in use in 1938 and approved by the FDA in 1939. Anabolic steroids, derivatives of testosterone, have been used illicitly and are now controlled substances. Testosterone, like many anabolic steroids, was classified as a controlled substance in 1991. Testosterone therapy is administered parenterally in regular and delayed-release (depot) dosage forms. In September 1995, the FDA initially approved testosterone transdermal patches (Androderm); many transdermal forms and brands are now available including implants, gels, and topical solutions. A testosterone buccal system, Striant, was FDA approved in July 2003; the system is a mucoadhesive product that adheres to the buccal mucosa and provides a controlled and sustained release of testosterone. In May 2014, the FDA approved an intranasal gel formulation (Natesto). A transdermal patch (Intrinsa) for hormone replacement in women is under investigation; the daily dosages used in women are much lower than for products used in males. The FDA ruled in late 2004 that it would delay the approval of Intrinsa women’s testosterone patch and has required more data regarding safety, especially in relation to cardiovascular and breast health.

The Enanthate Ester: An ester is any of a class of organic compounds that react with water to produce alcohols and organic or inorganic acids.  Most esters are derived from carboxylic acids, and injectable testosterone is typically administered along with one or multiple esters.  The addition of a carbon chain (ester) attached to the testosterone molecule controls how soluble it will be once inside the bloodstream.  The smaller the carbon chain, the shorter the ester, and the more soluble the medication.  A small/short ester will have a shorter half life – a repeating cycle of a medication’s time and activity within the body.  The inverse is true of long carbon chains, like enanthate, which both act slowly upon the body and evacuates the body at a similar rate. Specifically, testosterone enanthate injection contains the carboxylic acid ester (enanthic acid), and a half-life is approximately 8-9 days; the longest half-life of all common ester based testosterones.  An uncommon testosterone such as Nebido (testosterone undecanoate) has a very long 3-month half-life.


Testosterone Enanthate injection are primarily used I men who do not make enough testosterone naturally (hypogonadism), as well as in specific adolescent cases to induce puberty in those with delayed puberty.

Mechanism of Action
Endogenous testosterone is responsible for sexual maturation at all stages of development throughout life. Synthetically, it is prepared from cholesterol. The function of androgens in male development begins in the fetus, is crucial during puberty, and continues to play an important role in the adult male. Women also secrete small amounts of testosterone from the ovaries. The secretion of androgens from the adrenal cortex is insufficient to maintain male sexuality.

Increased androgen plasma concentrations suppress gonadotropin-releasing hormone (reducing endogenous testosterone), luteinizing hormone, and follicle-stimulating hormone by a negative-feedback mechanism. Testosterone also affects the formation of erythropoietin, the balance of calcium, and blood glucose. Androgens have a high lipid solubility, enabling them to rapidly enter cells of target tissues. Within the cells, testosterone undergoes enzymatic conversion to 5-alpha-dihydro testosterone and forms a loosely bound complex with cytosolic receptors. Androgen action arises from the initiation of transcription and cellular changes in the nucleus brought about by this steroid-receptor complex.

Normally, endogenous androgens stimulate RNA polymerase, resulting in an increased protein production.These proteins are responsible for the normal male sexual development, including the growth and maturation of the prostate, seminal vesicle, penis, and scrotum. During puberty, androgens cause a sudden increase in growth and development of muscle, with redistribution of body fat. Changes also take place in the larynx and vocal cords, deepening the voice. Puberty is completed with beard development and growth of body hair. Fusion of the epiphyses and termination of growth is also governed by the androgens, as is the maintenance of spermatogenesis. When endogenous androgens are unavailable, use of exogenous androgens is necessary for normal male growth and development.

**NOTE**  The content contained in this blog is subject to interpretation and is the opinion of the content writer.  We do not claim it to be fact.  We encourage you to consult a medical doctor before taking any prescribed medications or supplements.

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