Terminal Half-lives
- Testosterone Propionate: 0.8 days
- Testosterone Phenylpropionate: 1.5 days
- Testosterone Isocaproate: 4.0 days
- Testosterone Enanthate: 4.5 days
- Testosterone Cypionate: 5.0 days
- Testosterone Decanoate: 7.5 days
- Testosterone Undecanoate: 20.9 days
- Trenbolone Acetate: 1.0 days
- Trenbolone Enanthate: 4.5 days
- Masteron Propionate: 0.8 days
- Masteron Enanthate: 4.5 days
- Nandrolone Phenylpropionate: 1.5 days
- Nandrolone Decanoate: 7.5 days
- Equipoise: 14.0 days
- Primobolan Oral: 5 hours
- Primobolan Injectable: 4.5 days
- Halotestin: 7 hours
- Anadrol: 14 hours
- Dianabol: 5 hours
- Turinabol: 16 hours
- Winstrol Oral: 8 hours
- Winstrol Injectable: 1.0 days
- Anavar: 10 hours
- Superdrol: 10 hours
These half-lives are approximations, and may vary slightly depending on injection site, carrier oil, and other factors.
Note: A different list of half-lives is often copy and pasted on various sites, claiming that, for example, the half-life for the propionate ester is 4.5 days and that the half-life for the enanthate ester is 10.5 days. This list is incorrect, and is the result of flawed calculations many years ago. See the "References" section for more information.
from steroid calc
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
Winstrol (stanozolol) (tablets or depot taken orally) 9 hours
Depot steroids Drug Active half-life
Deca-durabolin (Nandrolone decanate) 14 days
Equipoise 14 days
Finaject (trenbolone acetate) 3 days
Primobolan (methenolone enanthate) 10.5 days
Sustanon or Omnadren 15 to 18 days
Testosterone Cypionate 12 days
Testosterone Enanthate 10.5 days
Testosterone Propionate 4.5 days
Testosterone Suspension 1 day
Winstrol (stanozolol) 1 day
Steroid esters Drug Active half-life
Formate 1.5 days
Acetate 3 days
Propionate 2 days
Phenylpropionate 4.5 days
Butyrate 6 days
Valerate 7.5 days
Hexanoate 9 days
Caproate 9 days
Isocaproate 9 days
Heptanoate 10.5 days
Enanthate 10.5 days
Octanoate 12 days
Cypionate 12 days
Nonanoate 13.5 days
Decanoate 15 days
Undecanoate 16.5 days
Ancillaries Drug Active half-life
Arimidex 3 days
Clenbuterol 1.5 days
Clomid 5 days
Cytadren 6 hours
T3 10 hours
Active Life versus Half Life
The confusion comes from the 2 terms being used synonymously when they should not be. "Half-life is not a reference for the total time a drug will be found active in the body. It may take several half-lives before the drug is completely inactive."
Half-life: The period of time required for the concentration or amount of drug in the body to be reduced to exactly one-half of a given concentration or amount.
Example: The half-life of anavar is 9 hours+/- (9 hours after oral administration of 50 mg of anavar, 25mg is still present in the body).
Active life: Refers to the period in which the amount of a drug in the body is enough that it will still produce the desired effects for which it was administered. Or conversely, inhibit natural recovery of normal bodily function. It is dose dependent.
Example: The active life of 1,000mg of testosterone decanoate would be more than one month. At day 30 after injection, 250mg or more of this drug would still be present in the body.
WHAT AN ESTER IS, AND HOW IT WORKS
I'm sure that if you have taken an interest in anabolic steroids you have noticed the similarities on the labeling of many drugs. Let's look at testosterone for example. One can find compounds like testosterone cypionate, enanthate, propionate, heptylate; caproate, phenylpropionate, isocaproate, decanoate, acetate, the list goes on and on. In all such cases the parent hormone is testosterone, which had been modified by adding an ester (enanthate, propionate etc.) to its structure. The following question arises: What is the difference between the various esterified versions of testosterone in regards to their use in bodybuilding?
An ester is a chain composed primarily of carbon and hydrogen atoms. This chain is typically attached to the parent steroid hormone at the 17th carbon position (beta orientation), although some compounds do carry esters at position 3 (for the purposes of this article it is not crucial to understand the exact position of the ester). Esterification of an injectable anabolic/androgenic steroid basically accomplishes one thing, it slows the release of the parent steroid from the site of injection. This happens because the ester will notably lower the water solubility of the steroid, and increase its lipid (fat) solubility. This will cause the drug to form a deposit in the muscle tissue, from which it will slowly enter into circulation as it is picked up in small quantities by the blood. Generally, the longer the ester chain, the lower the water solubility of the compound, and the longer it will take to for the full dosage to reach general circulation.
Slowing the release of the parent steroid is a great benefit in steroid medicine, as free testosterone (or other steroid hormones) previously would remain active in the body for a very short period of time (typically hours). This would necessitate an unpleasant daily injection schedule if one wished to maintain a continuous elevation of testosterone. By adding an ester, injections can be as infrequent as once per week or longer, instead of having to constantly re-administer the drug to achieve the desried effect. Clearly without the use of an ester, maintaining constant blood levels with an injectable anabolic/androgen would be much more difficult.
Esterification temporarily deactivates the steroid molecule. With a chain blocking the 17th beta position, binding to the androgen receptor is not possible (it can exert no activity in the body). In order for the compound to become active the ester must therefore first be removed. This automatically occurs once the compound has filtered into blood circulation, where esterase enzymes quickly cleave off (hydrolyze) the ester chain. This will restore the necessary hydroxyl (OH) group at the 17th beta position, enabling the drug to attach to the appropriate receptor. Now and only now will the steroid be able to have an effect on skeletal muscle tissue.
You can start to see why considering testosterone cypionate much more potent than enanthate makes little sense, as your muscles are seeing only free testosterone no matter what ester was used to deploy it.
ACTIONS OF DIFFERENT ESTERS
There are many different esters that are used with anabolic/androgenic steroids, but again, they all do basically the same thing. Esters vary only in their ability to reduce a steroid's water solubility. An ester like propionate for example will slow the release of a steroid for a few days, while the duration will be up to 15 days+/- with a decanoate ester. Esters have no effect on the tendency for the parent steroid to convert to estrogen or DHT (dihydrotestosterone: a more potent metabolite) nor will it effect the overall muscle-building potency of the compound. Any differences in results and side effects that may be noted by bodybuilders who have used various esterified versions of the same base steroid are just issues of timing.
