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Active Half-Life of Steroids

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  • Active Half-Life of Steroids

    An important consideration when planning a steroid cycle, in particular the timing of dosing to be administered, is the active half-life of the drug being employed. The half-life may be defined as the time (t) the level is half of the starting level of a given compound; at time 2t, the level is a quarter of the starting level, and at time 3t, the level is an eighth of the starting level, and so on.

    This information is vital in the timing of the dosing when attempting to achieve a more stable blood concentration, which leads to greater overall results and maintenance of gains. Some fluctuations of concentration levels are acceptable, and are also mostly unavoidable, but should be kept to a minimum.

    This article covers the half-life's of the most commonly used steroids, esters and ancillary compounds.

    Oral steroids

    Drug Active half-life
    Anadrol / Anapolan50 (oxymetholone) 8 to 9 hours
    Anavar (oxandrolone) 9 hours
    Dianabol (methandrostenolone, methandienone) 4.5 to 6 hours
    Methyltestosterone 4 days
    Winstrol (stanozolol)
    (tablets or depot taken orally) 9 hours
    Steroid esters

    The half-life applies to the ester regardless of hormone attached, for example trenbolone enanthate and primobolan (methenolone enanthate) will act very similarly to testosterone enanthate in terms of release rate.

    Drug Active half-life

    Suspension within 1 hour
    Acetate 1 day
    Propionate 1 day
    Phenylpropionate 1-2 days
    Butyrate 2-3 days
    Valerate 3 days
    Hexanoate 3 days
    Caproate 4-5 days
    Isocaproate 4-5 days
    Heptanoate 5-6 days
    Enanthate 5-6 days
    Octanoate 6-7 days
    Cypionate 6-7 days
    Nonanoate 7 days
    Decanoate 7-8 days
    Undeclenate 8-9 days
    Undecanoate Approx 20 days

    Ancillaries

    Drug Active half-life
    Arimidex 3 days
    Clenbuterol 1.5 days
    Clomid 5 days
    Cytadren 6 hours
    Ephedrine 6 hours
    T3 10 hours

  • #2
    Very useful info.

    Comment


    • #3
      Very useful info.
      I agree - and interesting.

      Comment


      • #4
        Not to want to know better but completely unscientific. You can find these charts all over the net. It could be true, providing all these active ingredients where compounded in the same oil -solvents - co-solvents -preservatives. Look at this study and I have many more a university in Sweden does very good research to optimal carriers/pharmacokenetics/drugdelivery

        Objective:
        In the search for long-acting testosterone preparations suited for substitution therapy of hypogonadal men, testosterone undecanoate (TU) dissolved in either tea seed oil or castor oil was investigated.
        Design:
        * In study I, 1000 mg TU in tea seed oil (125 mg/ml) were injected in equal parts into the gluteal muscles of seven hypogonadal men.
        * In study II, 1000mg TU in castor oil (250 mg/ml) were injected
        into one gluteal muscle of 14 patients.
        Results:
        In comparison with published data on testosterone enanthate, most widely used for i.m. injections, the kinetic profiles of both TU preparations showed extended half-lives and serum levels not exceeding the upper limit of normal.
        The TU-castor oil preparation had a longer half-life than TU in tea
        seed oil 34 vs 21 days
        European Journal of Endocrinology 140 414–419
        RonnyT
        Senior Member
        Last edited by RonnyT; 03-16-2011, 07:31 PM.

        Comment


        • #5
          To explain in short:
          in the chart approx. 20 days
          testosterone undecanoate in tea seed oil had a half life of 21 days
          testosterone undecanoate in castor oil had a half life of 34 days

          This study was done in respect to MENT. They want means that stay stable for a long time and injection intervals as long as possible. Thats also why long ago Sustanon was created for hormone replacement.

          Comment


          • #6
            an other aspect

            We also have to concidder the volume (cq dosis) and the injectionspot.
            The dissapearence rate of nandrolone decanoate in human males.
            If you're really interested I can post more about this subject..
            Attached Files

            Comment


            • #7
              I find it interesting and always want to learn more. I don't know about anyone else.
              goanywhere
              Senior Member
              Last edited by goanywhere; 03-16-2011, 09:28 PM.

              Comment


              • #8
                Originally posted by RonnyT View Post
                We also have to concidder the volume (cq dosis) and the injectionspot.
                The dissapearence rate of nandrolone decanoate in human males.
                If you're really interested I can post more about this subject..
                The study of your graphic: http://jpet.aspetjournals.org/content/281/1/93.full

                Comment


                • #9
                  Yep and you can download the whole study here http://www.eje-online.org/cgi/conten...ract/140/5/414 the pdf on the right side of the page.

                  Comment


                  • #10
                    http://www.ncbi.nlm.nih.gov/pubmed/12954670


                    This study (on monkeys) showed that 100 mg Testosteron Undecanoate (100 mg pure testosterone base, thus without the esterweight) was (at least) 2,5times as effective as 100 mg Testosterone Enanthate. Which means that this study proved that the estrification has a definite influence on the bioavailability

                    Pharmacokinetics and degree of aromatization rather than total dose of different preparations determine the effects of testosterone: a nonhuman primate study in Macaca fascicularis.
                    Weinbauer GF, Partsch CJ, Zitzmann M, Schlatt S, Nieschlag E.
                    Institute of Reproductive Medicine of the University, Domagkstrasse 11, D-48129 M?nster, Germany.
                    Abstract
                    Currently available testosterone (T) preparations differ substantially in their pharmacokinetic profile that might influence their androgenic properties in terms of suppression of the gonadal axis, effects on anabolic parameters, lipid metabolism, and erythropoiesis. The present work was undertaken to determine the physiological effects of three T preparations with different serum kinetics. Twenty adult male cynomolgus monkeys (Macaca fascicularis) were randomly assigned to receive treatment for 28 weeks with either T enanthate (TE) every 4 weeks, T buciclate (TB) every 7 weeks, or T undecanoate (TU) every 10 weeks or remaining untreated (controls). Each injection delivered 20 mg pure T per kilogram body weight. Pharmacokinetic profiles demonstrated higher peak levels of T for TE-treated animals; serum half-lives were longer for TU or TB. Estradiol levels (area under the curve) were significantly higher in TB vs TU or TE. All T regimens suppressed serum luteinizing hormone bioactivity and testicular volumes declined (all P <.001 vs controls). Sperm counts were markedly lowered in all animals but least in TE (P <.01 vs TB or TU). During recovery phase, return to normal for all three parameters occurred significantly earlier in TE-treated animals, followed by those given TU, compared with TB (all P <.001 between groups). Body weight increased significantly during T exposure. This effect was stronger and more sustained in TB vs TU or TE (both P <.001). Serum creatinine and hemoglobin increased with high significance in all T-treated animals (all P <.001 vs controls). The lowering impact of T on serum lipids was markedly stronger in the longer-acting T preparations in comparison with TE, as were effects on purine metabolism (all P <.001). The pattern of exposure and degree of aromatization rather than overall exposure to T determine its effects in the preclinical primate model. Both fluctuations of androgen concentrations and the conversion rate to estradiol influence gonadal suppression as well as metabolism. These results have to be considered in men receiving treatment for hypogonadism or regimens for hormonal contraception.

                    Comment


                    • #11
                      I have read over the net that cyp and enanth could actually have a half life of3-4 days.. and others say10 days. How do we know which are right

                      Comment


                      • #12
                        Interesting. A lot of it was over my head. Thank you Dino and Ronny.

                        Simple me was trying to learn about half life's - but I think you point is - it depends on lots of factors so there is no hard and fast rule or one-size-fits all.

                        Things that can make a difference:

                        1. Injection Site

                        2. What T is mixed with (caster oil vs tea oil)

                        Even the amount of estrogen varies by compound. Think I will try to avoid TB.

                        Comment


                        • #13
                          DIfferent way of coming at it, but the data I've seen on cypionate suggest that the body metabolizes 9% of your dose each 24 hours. I understand that enanthate isn't much different. It would work out to a half-life consistent with one of the earlier posts.

                          Comment


                          • #14
                            Originally posted by iamready View Post
                            I have read over the net that cyp and enanth could actually have a half life of3-4 days.. and others say10 days. How do we know which are right
                            If memory serves me - I had heard 8 days for cyp. Which is right in line with 6-7 days above. If my understanding of the articles here is fair - it can also vary by Mfg. as their base or what they are mixing with can vary.
                            goanywhere
                            Senior Member
                            Last edited by goanywhere; 03-18-2011, 12:06 AM.

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                            • #15
                              Bound or Free?

                              Are the half lifes measured here for bound T? Free T? Or total? In my simple understanding - bound is useless. Free is what counts.

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