Trenbolone enanthates half life

A Beginner's Guide To...
Testosterone Esters
by: Gerhard Waitz
January, 2001 © Iron Magazine Online L.L.C.

Disclaimer: This article is for entertainment purposes only. DO NOT follow any of the advice given in this article without the supervision of a trained medical professional. Ironmag.com accepts no responsibility for the actions of anyone reading this article.

You'll find more information and varying opinions from many different self-proclaimed experts on the subject of testosterone esters. After all it is one of the most misunderstood subjects in the world of steroids. Most people simply do not know what an ester--the mechanism by which injectable esterified steroids like testosterone cypionate, testosterone enanthate, and Sustanon is let alone know or have a good working knowledge of how it works. Arguments over the superiority of cypionate to enanthate, or Sustanon to all other testosterones are of course very common. This article is designed to take a look at the ester and what specifically it does to a steroid...

What is an ester?

I'm sure that if are educated in any way on the subject of anabolic steroids you have noticed the similarities on the labeling of many injectable steroids. A good example of this sort of similar labeling is testosterone. You will find compounds like testosterone cypionate, enanthate, propionate, heptylate, caproate, phenylpropionate, isocaproate, decanoate, acetate, and even more (which are less common). In this situation the main hormone is testosterone, and each testosterone has been modified by adding an ester to its structure, hence their additional names. So comes one of the most common questions in bodybuilding. What is the difference between the various testosterone esters and how do they differ in reference to their use in bodybuilding? The answer in as simple terms as I am able is as follows.
An ester is a chain composed primarily of carbon and hydrogen atoms. This chain is usually attached to the parent steroid hormone at the 17th carbon position, although some compounds do carry esters at position 3. Esterification of testosterone at position 17 with propionic or enanthic acid prolongs the intramuscular retention and the duration of activity of testosterone in proportion to the length of the fatty acid. When administered intramuscularly, the androgen ester is slowly absorbed into the circulation where it is then rapidly metabolized to an active unesterified testosterone. Intrinsic potency, bioavailability, and rate of clearance from the circulation are determinants of the biological activity of androgens. 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, in some cases only a few hours. This would necessitate an unpleasant daily injection schedule if one wished to maintain a continuous elevation of testosterone. By adding an ester, the user can inject as infrequently as once per month, instead of having to constantly re-administer the drug to achieve an optimum effect. Clearly without the use of an ester, muscle growth 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 hydrolyze the ester chain. The great majority of hydrolysis occurs with the help of enzymes or by non-specific reactions with proteins. These reactions cannot take place while the esterified steroid is dissolved in fat. Thus, while the esterified steroids are dissolved in fat, they are protected from hydrolyis, and thus serve as a depot for the drug, giving extended duration of action. This will restore the necessary hydroxyl group at the 17th beta position, enabling the drug to attach to the appropriate receptor. When this occurs the steroid is able to have an effect on skeletal muscle tissue.

So what are the actions of different esters?

Even though there are several different esters used with anabolic/androgenic steroids, 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 or a few days, while the duration will be weeks with a decanoate ester. Esters have no effect on the tendency for the parent steroid to convert to estrogen or DHT (dihydrotestosterone- for the new user) nor will it affect the overall muscle-building effectiveness 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. Testosterone enanthate causes estrogen related problems more readily than Sustanon, simply because with enanthate testosterone levels will peak much sooner (1-2 week release duration as opposed to 3 or 4). Likewise testosterone suspension is the worst in regards to gynecomastia and water retention because blood hormone levels peak rapidly with this drug. Instead of waiting weeks for testosterone levels to rise to their highest point, they do so in only a few days. Given an equal blood level of testosterone, there would be no difference in the rate of aromatization or DHT conversion between different esters. There is simply no mechanism for this to be physically possible. There is however one way that we can say an ester does technically affect potency; it is calculated in the steroid weight. The heavier the ester chain, the greater is its percentage of the total weight. In the case of testosterone enanthate for example, 250mg of the esterfied testosterone is equal to only 180mg of free testosterone. 70mgs out of each 250mg injection is the weight of the ester. In fact based on this fact alone, we could consider enanthate slightly more potent than cypionate, which at least among European bodybuilders, which I'm most in contact with goes against what is commonly thought, as its ester chain contains one less carbon atom (therefore taking up a slightly smaller percentage of total weight). One study stated that 140 mg. of testosterone cypionate and testosterone enanthate produced similar blood levels after injection, and stated that heightened blood levels decreased to basal levels by day ten.
Propionate would of course come out on top of the three, releasing a measurable (but not significant) amount more testosterone per injection than cypionate or enanthate.

Information on specific esters that should help you:

Propionate:
Also referred to as Carboxyethane; hydroacrylic acid; Methylacetic acid;
Ethylformic acid; Ethanecarboxylic acid; metacetonic acid; pseudoacetic acid; Propionic Acid. Propionate esters will slow the release of a steroid for several days. To keep blood levels from fluctuating greatly, propionate compounds are usually injected two to three times weekly.

Acetate:
Also referred to as Acetic Acid; Ethylic acid; Vinegar acid; vinegar; Methanecarboxylic acid. Acetate esters delay the release of a steroid for only a couple of days. Contrary to what you may have read, acetate esters do not increase the tendency for adipose tissue removal. There is simply no known mechanism for it to do so. This ester is used on oral primobolan tablets (metenolone acetate), Finaplix (trenbolone acetate) implant pellets, and occasionally testosterone.

Isocarpoate:
Also referred to as Isocaproic Acid; isohexanoate; 4-methylvaleric acid.
Isocaproate begins to near enanthate in terms of release. The duration is still shorter, with a notable hormone level being sustained for approximately one week. This ester is used with testosterone in the blended products Sustanon and Omnadren.

Phenylpropionate:
Also referred to as Propionic Acid Phenyl Ester. Phenylpropionate will extend the release of active steroid a few days longer than propionate. To keep blood levels even, injections are given at least twice weekly. Durabolin is the drug most commonly seen with a phenylpropionate ester (nandrolone phenylpropionate), although it is also used with testosterone in Sustanon and Omnadren.

Caproate:
Also referred to as Hexanoic acid; hexanoate; n-Caproic Acid; n-Hexoic acid;
butylacetic acid; pentiformic acid; pentylformic acid; n-hexylic acid; 1-pentanecarboxylic acid; hexoic acid;1-hexanoic acid; Hexylic acid; Caproic acid. This ester is identical to
isocarpoate in terms of atom count and weight, but is laid out slightly different (Isocaproate has a split configuration, difficult to explain here but easy to see on paper). Release duration would be very similar to isocaproate (levels sustained for approximately one weak), perhaps coming slightly closer to enanthate due to its straight chain. Caproate is the slowest releasing ester used in Omnadren, which is why most athletes notice more water retention with this compound.

Enanthate:
Also referred to as heptanoic acid; enanthic acid; enanthylic acid; heptylic acid; heptoic acid; Oenanthylic acid; Oenanthic acid. Enanthate is one of the most prominent esters used in steroid manufacture (most commonly seen with testosterone but is also used in other compounds like Primobolan Depot). Enanthate will release a steady (yet fluctuating as all esters are) level of hormone for approximately 10-14 days. Although in medicine, enanthate compounds are often injected on a bi-weekly or monthly basis, athletes will inject once or twice weekly to help maintain a uniform blood level ranging from 3.5-7 days.

Cypionate:
Also referred to as Cyclopentylpropionic acid, cyclopentylpropionate.Cypionate is a very popular ester, although it is scarcely found outside the United States and Canada. Its release duration is almost identical to enanthate (10-14 days), and the two are likewise thought to be interchangeable in U.S. medicine. Athletes commonly hold the belief than cypionate is more powerful than enanthate, although realistically there is little difference between the two. The enanthate ester is in fact slightly smaller than cypionate, and it therefore releases a small (perhaps a few milligrams) amount of steroid more in comparison. Commonly injected through athletes every 3.5-5 days on average.

Decanoate:
Also referred to as decanoic acid; capric acid; caprinic acid; decylic acid, Nonanecarboxylic acid. The Decanoate ester is most commonly used with the hormone nandrolone (as in Deca-Durabolin) and is found in virtually all corners of the world. Testosterone decanoate is also the longest acting constituent in Sustanon, greatly extending its release duration. The release time with Decanoate compounds is listed to be as long as one month, although most recently we are finding that levels seem to drop significantly after two weeks. To keep blood levels more uniform, athletes (as they have always known to do) will follow a weekly injection schedule.

Undecylenate:
Also referred to as Undecylenic acid; Hendecenoic acid; Undecenoic acid. This ester is very similar to decanoate, containing only one carbon atom more. Its release duration is likewise very similar (approximately 2-3 weeks), perhaps extending a day or so past that seen with decanoate. Undecylenate seems to be exclusive to the veterinary preparation Equipoise (boldenone undecylenate), although there is no reason it would not work well in human-use preparations (Equipoise certainly works fine for athletes). Again, weekly injections are most common.

Undecanoate:
Also referred to as Undecanoic Acid; 1-Decanecarboxylic acid; Hendecanoic acid; Undecylic acid. Undecanoate is not a commonly found ester, and only appears to be used in the nandrolone preparation Dynabolan, and oral testosterone undecanoate (Andriol). Since this ester is chemically very similar to undecylenate (it is only 2 hydrogen atoms larger), it has a similar release duration (approximately 2-3 weeks). Although this ester is used in the oral preparation Andriol, there is no reason to believe it carries any properties unique of other esters. Andriol in fact works very poorly at delivering testosterone, bolstering the idea that oral administration is not the ideal use of esterified androgens.

Laurate:
Also referred to as Dodecanoic acid, laurostearic acid, duodecyclic acid, 1-undecanecarboxylic acid, and dodecoic acid. Laurate is the longest releasing ester used in commercial steroid production, although longer acting esters do exist. Its release duration would be closer to one month than the other esters listed above, although realistically we are probably to expect a notable drop in hormone level after the third week. Laurate is exclusively found in the veterinary nandrolone preparation Laurabolin, perhaps seen as slightly advantageous over a decanoate ester due to a less frequent injection schedule. Again athletes will most commonly inject this drug weekly, no doubt in part due to its low strength (25mg/ml or 50mg/ml).

Other points to ponder

While there are a number of interesting oral steroids that, at first glance, would be appe****g candidates for making esters, in fact there are very good reasons why no such products are available. Indeed, there are absolutely no 17-alkylated steroid esters on the market. They would be difficult to synthesize. The 17-methyl group, which works to block liver enzymes from reacting with the steroid molecule, will also hinder the material one would use to make the ester from reacting with the steroid. As a result, you will not see esters of Winstrol, Anadrol, or any 17-alkylated steroid on the market, and don't recommend that anyone try making them. They would probably be inactive, or if they would have any activity, it would be very low.

Another note: (one that I shouldn't need to tell you) is that all testosterone drugs aromatize, and if estrogenic effects are not desired, then anti-estrogenic agents should be used for any of the esters and in the same manner, regardless of the ester used.

So there you have it; a beginners guide to testosterone esters. This should help you understand what esters are and make choosing them a whole lot easier.

References:
Junkmann K. Long-acting steroids in reproduction. Recent Prog Horm Res. 1957;13:389-419.

Fujioka M, Shinohara Y, Baba S, Irie M, Inoue K. Pharmacokinetic properties of testosterone propionate in normal men. J Clin Endocrinol Metab. 1986;63:1361-4.

Schurmeyer T, Nieschlag E. Comparative pharmacokinetics of testosterone enanthate and testosterone cyclohexanecarboxylate as assessed by serum and salivary testosterone levels in normal men. Int J Androl. 1984;7:181-7.

Schulte-Beerbuhl M et al., "Comparison of testosterone, dihydrotestosterone, luteinizing hormone, and follicle-stimulating hormone in serum after injection of testosterone enanthate or testosterone cypionate." Fertility and Sterility (1980) 33.2 : 201-203