Testosterone Cypionate

Testosterone cypionate is a slow-acting injectable form of the androgen testosterone. Following deep intramuscular injection, the drug provides a sustained release of testosterone into the bloodstream for 2 to 3 weeks.14 Testosterone cypionate possesses a half-life of 10-12 days. The most commonly recommended dosing regimen for TRT is is 75 to 100 mg every week or 150 to 200 mg every other week. Typically, 26-52 injections are required per year.


Testosterone Enanthate

Similar to testosterone cypionate, testosterone enanthate is a slow-acting injectable form of the androgen testosterone. Following deep intramuscular injection, the drug provides a sustained release of testosterone into the bloodstream for 2 to 3 weeks.14 Testosterone enanthate possesses a half-life of 8-10 days. The most commonly recommended dosing regimen for TRT is is 75 to 100 mg every week or 150 to 200 mg every other week. Typically, 26-52 injections are required per year.


Testosterone Propionate

In comparison to testosterone enanthate and testosterone cypionate, testosterone propionate is a faster-acting form of the androgen testosterone. Testosterone propionate possesses a half-life of roughly 1-2 days. Therefore, testosterone propionate does not provide a sustained release. Due to this short half-life, it must be injected every other day or every third day. As a result, it is rarely used for TRT.


Testosterone Undecanoate

Testosterone undecanoate is very slow-acting injectable form of the androgen testosterone. Following deep intramuscular injection, the drug provides a sustained release of testosterone into the bloodstream for up to 10 weeks. Testosterone undecanoate has been available under the brand name Nebido for over 10 years in more than 80 countries. However, it was not approved for use in the US.

Recently, however, the US FDA approved injectable testosterone undecanoate (2014). Endo Pharmaceuticals will market it under the brand name Aveed. Aveed is a depot formulation of testosterone undecanoate (TU) indicated for long-term TRT. Testosterone injections of 750 mg Aveed maintain normal levels between 300 and 1000 ng/dL for up to 10 weeks. Following baseline administration of 750 mg, a second 750 mg dose is given at 4 weeks followed by 750 mg every 10 weeks thereafter.

Due to the very slow-acting nature, Aveed will offer men with low testosterone a more convenient treatment option than currently available preparations. The injection interval for TU, after the loading dose, is 10 weeks. This equates to approximately 5 injections per year. In comparison, testosterone gels require daily dosing and testosterone enanthate and testosterone cypionate require injections every other week (26 injections per year).