Active Half-Life of Steroids

[dr.Stack Member Find all posts View Profile Close dr.Stack]

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

[sixteentons Senior Member Find all posts View Profile Close sixteentons]

Very useful info.

[goanywhere Senior Member Find all posts View Profile Close goanywhere]

Very useful info.

I agree - and interesting.

[RonnyT Senior Member Find all posts View Profile Close RonnyT]

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 Find all posts View Profile Close RonnyT]

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.

[RonnyT Senior Member Find all posts View Profile Close RonnyT]

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..

[goanywhere Senior Member Find all posts View Profile Close goanywhere]

I find it interesting and always want to learn more. I don't know about anyone else.

[dino Senior Member Find all posts View Profile Close dino]

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

[RonnyT Senior Member Find all posts View Profile Close RonnyT]

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.

[RonnyT Senior Member Find all posts View Profile Close RonnyT]

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.

[iamready Senior Member Find all posts View Profile Close iamready]

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

[goanywhere Senior Member Find all posts View Profile Close goanywhere]

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.

[Bo Deen Junior Member Find all posts View Profile Close Bo Deen]

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.

[goanywhere Senior Member Find all posts View Profile Close goanywhere]

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 Find all posts View Profile Close goanywhere]

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.