page_title: Pharmacokinetics of testosterone
section_title: Intramuscular injection
hierarchical_section_title: Pharmacokinetics of testosterone / Routes of administration / Intramuscular injection
caption_attribution_description: English: I made this, anyone can use it. Created from source material using WebPlotDigitizer and Plotly. Source of the values: January 2010 Andrology: Male Reproductive Health and Dysfunction, Springer Science &amp; Business Media, pp.&#160;444– ISBN&#58; 978-3-540-78355-8.&#32;
context_page_description: The pharmacology of testosterone, an androgen and anabolic steroid medication and naturally occurring steroid hormone, concerns its pharmacodynamics, pharmacokinetics, and various routes of administration.
  Testosterone is a naturally occurring and bioidentical AAS, or an agonist of the androgen receptor, the biological target of androgens like endogenous testosterone and dihydrotestosterone.
  Testosterone is used by both men and women and can be taken by a variety of different routes of administration.
context_section_description: Testosterone can be administered by intramuscular injection either as an aqueous suspension of testosterone or as an oil solution or aqueous suspension of testosterone esters such as testosterone propionate, testosterone enanthate, testosterone cypionate, testosterone undecanoate, and testosterone isobutyrate. An even longer-acting testosterone ester that was developed but ultimately never marketed is testosterone buciclate. These preparations are prodrugs of progesterone that have a long-lasting depot effect when injected into muscle or fat, ranging from days to months in duration.
  The bioavailability of drugs that are administered intramuscularly is generally almost 95%.
  As oil solutions by intramuscular injection, the elimination half-lives of testosterone esters are 0.8 days for testosterone propionate, 4.5 days for testosterone enanthate, 20.9 days (in tea seed oil) and 33.9 days (in caster oil) for testosterone undecanoate, and 29.5 days for testosterone buciclate. The pharmacokinetics of testosterone cypionate are said to be the same as those of testosterone enanthate, with "extremely comparable" patterns of testosterone release. Due to their varying and different elimination half-lives, the different intramuscular testosterone esters are administered with differing frequencies. Testosterone propionate is injected two to three times per week, testosterone enanthate and testosterone cypionate are injected once every two to four weeks, and testosterone undecanoate and testosterone buciclate are injected once every 10 to 14 weeks. Due to its relatively short duration, testosterone propionate is now relatively little used and testosterone undecanoate is the preferred testosterone ester for intramuscular use. Testosterone undecanoate and testosterone buciclate can be injected intramuscularly as infrequently as four times per year.
  High doses of testosterone esters by intramuscular injection have been studied in healthy young men. Levels of testosterone with intramuscular injections of testosterone cypionate were about 700 ng/dL for 100 mg/week, 1100 ng/dL for 250 mg/week, and 2000 ng/dL for 500 mg/week. In another study, testosterone levels with 600 mg/week testosterone enanthate by intramuscular injection were 2,800–3,200 ng/dL.
  Intramuscular injection of testosterone propionate as an oil solution, aqueous suspension, and emulsion has been compared.
  Intramuscular injection of testosterone-containing biodegradeable microspheres has been studied.
caption: Testosterone levels over 16 weeks with intramuscular injection of different testosterone esters in hypogonadal men.[19]
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