Active Half-life of Steroids and Esters


Updated June 2010 by PartyBoy, MuscleTalk Moderator

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

DrugActive half-life
Anadrol / Anapolan50 (oxymetholone)8 to 9 hours
Anavar (oxandrolone)9 hours
Dianabol (methandrostenolone, methandienone)4.5 to 6 hours
Methyltestosterone4 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.

DrugActive half-life
Suspensionwithin 1 hour
Acetate1 day
Propionate1 day
Phenylpropionate1-2 days
Butyrate2-3 days
Valerate3 days
Hexanoate3 days
Caproate4-5 days
Isocaproate4-5 days
Heptanoate5-6 days
Enanthate5-6 days
Octanoate6-7 days
Cypionate6-7 days
Nonanoate7 days
Decanoate7-8 days
Undeclenate8-9 days
UndecanoateApprox 20 days

Ancillaries

DrugActive half-life
Arimidex3 days
Clenbuterol1.5 days
Clomid5 days
Cytadren6 hours
Ephedrine6 hours
T310 hours

A practical example is if one was to inject 100mg of testosterone propionate and allow blood levels to peak. In approx 36 hours time (half-life duration from the above tables) and providing no other injections had taken place, the level would be reduced to 50mg. Again, a further approx 36 hours down the line and levels would have dropped to 25mg, and the value keeps halving every approx 36 hours.

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