Androgen ester

An androgen or anabolic steroid ester is an ester of an androgen/anabolic steroid (AAS) such as the natural testosterone or dihydrotestosterone (DHT) or the synthetic nandrolone (19-nortestosterone). Esterification renders AAS into metabolism-resistant prohormones of themselves, improving oral bioavailability, increasing lipophilicity, and extending the elimination half-life (which necessitates less frequent administration). In addition, with intramuscular injection, AAS esters are absorbed more slowly into the body, further improving the elimination half-life. Aside from differences in pharmacokinetics (e.g., duration), these esters essentially have the same effects as the parent drugs.[1] They are used in androgen replacement therapy (ART), among other indications. Examples of androgen esters include testosterone esters such as testosterone cypionate, testosterone enanthate, testosterone propionate, and testosterone undecanoate and nandrolone esters such as nandrolone decanoate and nandrolone phenylpropionate.

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 solutionDelatestryl14–20 days
Testosterone cypionateOil solutionDepovirin14–20 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 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.
Pharmacokinetics of testosterone esters
Testosterone esterFormRoute of administrationElimination half-lifeMean residence time
Testosterone undecanoateOil-filled capsulesOral1.6 hours3.7 hours
Testosterone propionateOil solutionIntramuscular injection0.8 days1.5 days
Testosterone enanthateCastor oil solutionIntramuscular injection4.5 days8.5 days
Testosterone undecanoateTea seed oil solutionIntramuscular injection20.9 days34.9 days
Testosterone undecanoateCastor oil solutionIntramuscular injection33.9 days36.0 days
Testosterone buciclateaAqueous suspensionIntramuscular injection29.5 days60.0 days
Notes: Testosterone cypionate has very similar pharmacokinetics to TE. Footnotes: a = Never marketed. Sources: See template.
Structural properties of major testosterone esters
AndrogenStructureEsterRelative
mol. weight		Relative
T contentb		Durationc
PositionMoietyTypeLengthaRankGroup
Testosterone
––––1.001.0011Short
Testosterone propionate
C17βPropanoic acidStraight-chain fatty acid31.190.8410Short
Testosterone isobutyrate
C17βIsobutyric acidAromatic fatty acid– (~3)1.240.809Moderate
Testosterone cypionate
C17βCyclopentylpropanoic acidAromatic fatty acid– (~6)1.430.708Moderate
Testosterone phenylpropionate
C17βPhenylpropanoic acidAromatic fatty acid– (~6)1.460.697Moderate
Testosterone isocaproate
C17βIsohexanoic acidBranched-chain fatty acid– (~5)1.340.756Moderate
Testosterone caproate
C17βHexanoic acidStraight-chain fatty acid61.350.755Moderate
Testosterone enanthate
C17βHeptanoic acidStraight-chain fatty acid71.390.724Moderate
Testosterone decanoate
C17βDecanoic acidStraight-chain fatty acid101.530.653Long
Testosterone undecanoate
C17βUndecanoic acidStraight-chain fatty acid111.580.632Long
Testosterone buciclated
C17βBucyclic acideAromatic carboxylic acid– (~9)1.580.631Long
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 = Duration by intramuscular or subcutaneous injection in oil solution (except TiB and TB, which are in aqueous suspension). d = Never marketed. e = Bucyclic acid = trans-4-Butylcyclohexane-1-carboxylic acid. Sources: See individual articles.
Structural properties of major anabolic steroid esters
Anabolic steroidStructureEsterRelative
mol. weight		Relative
AAS contentb		Durationc
PositionMoietyTypeLengtha
Boldenone undecylenate
C17βUndecylenic acidStraight-chain fatty acid111.580.63Long
Drostanolone propionate
C17βPropanoic acidStraight-chain fatty acid31.180.84Short
Metenolone acetate
C17βEthanoic acidStraight-chain fatty acid21.140.88Short
Metenolone enanthate
C17βHeptanoic acidStraight-chain fatty acid71.370.73Long
Nandrolone decanoate
C17βDecanoic acidStraight-chain fatty acid101.560.64Long
Nandrolone phenylpropionate
C17βPhenylpropanoic acidAromatic fatty acid– (~6–7)1.480.67Long
Trenbolone acetate
C17βEthanoic acidStraight-chain fatty acid21.160.87Short
Trenbolone enanthated
C17βHeptanoic acidStraight-chain fatty acid71.410.71Long
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 androgen/anabolic steroid content by weight (i.e., relative androgenic/anabolic potency). c = Duration by intramuscular or subcutaneous injection in oil solution. d = Never marketed. Sources: See individual articles.
Testosterone undecanoate, an ester of testosterone and one of the most widely used androgen esters.

See also

References
  1. Richard Lawrence Miller (2002). The Encyclopedia of Addictive Drugs. Greenwood Publishing Group. pp. 416–. ISBN 978-0-313-31807-8.

Further reading


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