testosterone buciclate testosterone buciclate testosterone buciclate (developmental code names 20 aet-1, cdb-1781) is a synthetic, injected anabolic–androgenic steroid (aas) which was never marketed. it was developed in collaboration by the contraceptive development branch (cdb) of the national institute of child health and human development (nichd) and the world health organization (who) in the 1970s and early 1980s for use in androgen replacement therapy for male hypogonadism and as a potential male contraceptive. it was first described in 1986. the medication is an androgen ester – specifically, the c17β buciclate (4-butylcyclohexane-1-carboxylate) ester of testosterone – and is a prodrug of testosterone with a very long duration of action when used as a depot via intramuscular injection. testosterone buciclate is formulated as a microcrystalline aqueous suspension with a defined particle size of at least 75% in the range of 10 to 50 μm. testosterone buciclateclinical dataother namestestosterone bucyclate; testosterone 17β-buciclate; 20 aet-1; cdb-1781; testosterone 17β-(trans-4-butylcyclohexyl)carboxylateroutes ofadministrationintramuscular injectiondrug classandrogen; anabolic steroid; androgen esterpharmacokinetic databioavailabilityoral: very lowintramuscular: very highmetabolismliverelimination half-lifetea seed oil: 20.9 days (i.m.)castor oil: 33.9 days (i.m.)excretionurineidentifiers iupac name phenanthren-17-yl] 4-butylcyclohexane-1-carboxylate cas number105165-22-8pubchem cid114819chemspider19978531unii39bv4xz2cwcomptox dashboard (epa)dtxsid90909371 chemical and physical dataformulac30h46o3molar mass454.695 g·mol−13d model (jsmol)interactive image smiles ccccc1ccc(cc1)c(=o)o2cc32(cc43ccc5=cc(=o)cc45c)c inchi inchi=1s/c30h46o3/c1-4-5-6-20-7-9-21(10-8-20)28(32)33-27-14-13-25-24-12-11-22-19-23(31)15-17-29(22,2)26(24)16-18-30(25,27)3/h19-21,24-27h,4-18h2,1-3h3/t20?,21?,24-,25-,26-,27-,29-,30-/m0/s1key:odzdztoroxgjav-irwjkhrasa-n a single intramuscular injection of testosterone buciclate has been found to produce physiological levels of testosterone within the normal range in hypogonadal men for 3 to 4 months. the elimination half-life and mean residence time (average amount of time a single molecule of drug stays in the body) of testosterone buciclate were found to be 29.5 days and 60.0 days, respectively, whereas those of testosterone enanthate in castor oil were only 4.5 days and 8.5 days. testosterone buciclate also lasts longer than testosterone undecanoate, which has elimination half-lives and mean residence times of 20.9 days and 34.9 days in tea seed oil and 33.9 days and 36.0 days in castor oil, respectively. in addition, there is a spike in testosterone levels with testosterone enanthate and testosterone undecanoate that is not seen with testosterone buciclate, with which levels stay highly uniform and decrease very gradually and progressively. testosterone buciclate can maintain testosterone levels in the normal male range for up to 20 weeks with a single intramuscular injection. testosterone buciclate is able to reversibly and completely suppress spermatogenesis in men when used at sufficiently high dosages. as such, the results of clinical studies for use of testosterone buciclate as a male contraceptive were promising, and trials continued as late as 1995, but progress ultimately came to a standstill because the who was unable to find an industry partner willing to continue the development of the drug. because of this, the who backed away from testosterone buciclate and focused its research instead on testosterone undecanoate, which is also very long-lasting and has the advantage of having already been marketed and approved for medical use. androgen replacement therapy formulations and dosages used in men routemedicationmajor brand namesformdosage oraltestosteronea–tablet400–800 mg/day (in divided doses) testosterone undecanoateandriol, jatenzocapsule40–80 mg/2–4x day (with meals) methyltestosteronebandroid, metandren, testredtablet10–50 mg/day fluoxymesteronebhalotestin, ora-testryl, ultandrentablet5–20 mg/day metandienonebdianaboltablet5–15 mg/day mesterolonebprovirontablet25–150 mg/day sublingualtestosteronebtestoraltablet5–10 mg 1–4x/day methyltestosteronebmetandren, oreton methyltablet10–30 mg/day buccaltestosteronestrianttablet30 mg 2x/day methyltestosteronebmetandren, oreton methyltablet5–25 mg/day transdermaltestosteroneandrogel, testim, testogelgel25–125 mg/day androderm, andropatch, testopatchnon-scrotal patch2.5–15 mg/day testodermscrotal patch4–6 mg/day axironaxillary solution30–120 mg/day androstanolone (dht)andractimgel100–250 mg/day rectaltestosteronerektandron, testosteronbsuppository40 mg 2–3x/day injection (im or sc)testosteroneandronaq, sterotate, virosteroneaqueous suspension10–50 mg 2–3x/week testosterone propionatebtestovironoil solution10–50 mg 2–3x/week testosterone enanthatedelatestryloil solution50–250 mg 1x/1–4 weeks xyostedauto-injector50–100 mg 1x/week testosterone cypionatedepo-testosteroneoil solution50–250 mg 1x/1–4 weeks testosterone isobutyrateagovirin depotaqueous suspension50–100 mg 1x/1–2 weeks testosterone phenylacetatebperandren, androjectoil solution50–200 mg 1x/3–5 weeks mixed testosterone esterssustanon 100, sustanon 250oil solution50–250 mg 1x/2–4 weeks testosterone undecanoateaveed, nebidooil solution750–1,000 mg 1x/10–14 weeks testosterone buciclatea–aqueous suspension600–1,000 mg 1x/12–20 weeks implanttestosteronetestopelpellet150–1,200 mg/3–6 months notes: men produce about 3 to 11 mg testosterone per day (mean 7 mg/day in young men). footnotes: a = never marketed. b = no longer used and/or no longer marketed. sources: see template. pharmacokinetics of testosterone esters testosterone esterformroutetmaxt1/2mrt testosterone undecanoateoil-filled capsulesoral ?1.6 hours3.7 hours testosterone propionateoil solutionintramuscular injection ?0.8 days1.5 days testosterone enanthatecastor oil solutionintramuscular injection10 days4.5 days8.5 days testosterone undecanoatetea seed oil solutionintramuscular injection13.0 days20.9 days34.9 days testosterone undecanoatecastor oil solutionintramuscular injection11.4 days33.9 days36.0 days testosterone buciclateaaqueous suspensionintramuscular injection25.8 days29.5 days60.0 days notes: testosterone cypionate has similar pharmacokinetics to testosterone enanthate. footnotes: a = never marketed. sources: see template. parenteral durations of androgens/anabolic steroids medicationformmajor brand namesduration testosteroneaqueous suspensionandronaq, sterotate, virosterone2–3 days testosterone propionateoil solutionandroteston, perandren, testoviron3–4 days testosterone phenylpropionateoil solutiontestolent8 days testosterone isobutyrateaqueous suspensionagovirin depot, perandren m14 days mixed testosterone estersaoil solutiontriolandren10–20 days mixed testosterone estersboil solutiontestosid depot14–20 days testosterone enanthateoil solutiondelatestryl14–28 days testosterone cypionateoil solutiondepovirin14–28 days mixed testosterone esterscoil solutionsustanon 25028 days testosterone undecanoateoil solutionaveed, nebido100 days testosterone buciclatedaqueous suspension20 aet-1, cdb-1781e90–120 days nandrolone phenylpropionateoil solutiondurabolin10 days nandrolone decanoateoil solutiondeca durabolin21–28 days methandriolaqueous suspensionnotandron, protandren8 days methandriol bisenanthoyl acetateoil solutionnotandron depot16 days metenolone acetateoil solutionprimobolan3 days metenolone enanthateoil solutionprimobolan depot14 days note: all are via i.m. injection. footnotes: a = tp, tv, and tue. b = tp and tkl. c = tp, tpp, tica, and td. d = studied but never marketed. e = developmental code names. sources: see template. structural properties of major testosterone esters androgenstructureesterrelativemol. weightrelativet contentblogpc position(s)moiet(ies)typelengtha testosterone––––1.001.003.0–3.4 testosterone propionatec17βpropanoic acidstraight-chain fatty acid31.190.843.7–4.9 testosterone isobutyratec17βisobutyric acidaromatic fatty acid– (~3)1.240.804.9–5.3 testosterone isocaproatec17βisohexanoic acidbranched-chain fatty acid– (~5)1.340.754.4–6.3 testosterone caproatec17βhexanoic acidstraight-chain fatty acid61.350.755.8–6.5 testosterone phenylpropionatec17βphenylpropanoic acidaromatic fatty acid– (~6)1.460.695.8–6.5 testosterone cypionatec17βcyclopentylpropanoic acidcyclic carboxylic acid– (~6)1.430.705.1–7.0 testosterone enanthatec17βheptanoic acidstraight-chain fatty acid71.390.723.6–7.0 testosterone decanoatec17βdecanoic acidstraight-chain fatty acid101.530.656.3–8.6 testosterone undecanoatec17βundecanoic acidstraight-chain fatty acid111.580.636.7–9.2 testosterone buciclatedc17βbucyclic acidearomatic carboxylic acid– (~9)1.580.637.9–8.5 footnotes: a = length of ester in carbon atoms for straight-chain fatty acids or approximate length of ester in carbon atoms for aromatic fatty acids. b = relative testosterone content by weight (i.e., relative androgenic/anabolic potency). c = experimental or predicted octanol/water partition coefficient (i.e., lipophilicity/hydrophobicity). retrieved from pubchem, chemspider, and drugbank. d = never marketed. e = bucyclic acid = trans-4-butylcyclohexane-1-carboxylic acid. sources: see individual articles.