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Ester artical?


FOUNDING Member / Featured Member / Kilo Klub
Featured Member
Kilo Klub Member
Jul 22, 2002
I read a great artical explaining in depth Esters how they work... want to send it to a friend, but cannot track it down, can anyone help me out please.. thanks!
Ester info:


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 (the goal of testosterone replacement therapy). By adding an ester, the patient can visit the doctor as infrequently as once per month for his injection, instead of having to constantly re-administer the drug to achieve a therapeutic effect. Clearly without the use of an ester, therapy 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.


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 weeks 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.

Testosterone enanthate causes estrogen related problems more readily than Sustanon, simply because with enanthate testosterone levels will peak and trough much sooner (1-2 week release duration as opposed to 3 or 4). Likewise testosterone suspension is the worst in regards to gyno and water bloat because blood hormone levels peak so quickly with this drug. Instead of waiting weeks for testosterone levels to rise to their highest point, here we are at most looking at a couple of 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 possible.

There is however one way that we can say an ester does technically effect 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 esterified steroid (testosterone enanthate) is equal to only 180mg of free testosterone. 70mgs out of each 250mg injection is the weight of the ester. If we wanted to be really picky, we could consider enanthate slightly MORE potent than cypionate (I know this goes against popular thinking) as its ester chain contains one less carbon atom (therefore taking up a slightly smaller percentage of total weight). 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.

Sustanon: The "king" of testosterone blends. The four different testosterone esters in this product certainly look appealing to the consumer, there is no denying that. But for the athlete I think it is all just a matter of marketing (Hell, why buy one ester when you can get four. In clinical situations I can see some strong uses for it. If you were undergoing testosterone replacement therapy for example, you would probably find Sustanon a much more comfortable option than testosterone enanthate. You would need to visit the doctor less frequently for an injection, and blood levels should be more steadily maintained between treatments. But for the bodybuilder who is injecting 4 ampules of Sustanon per week, there is no advantage over other testosterone products. In fact, the high price tag for Sustanon usually makes it a very poor buy in the face of cheaper testosterone enanthate/cypionate. Bodybuilders should probably stop looking at the four ester issue, and stick with totals (Sustanon is just a 250mg testosterone ampule). Were enanthate to be available for say $10 per amp of 250mg, and Sustanon priced nearly double that, buying the Sustanon would be like throwing money away. If you could get nearly double the milligram amount for the same price with enanthate, this is the better product to go with hands down. Leave the high priced stuff for the guys who don't know any better.

While the advent of esters certainly constitutes an invaluable advance in the field of anabolic steroid medicine, clearly you can see that there is no magic involved here. Esters work in a well-understood and predictable manner, and do not alter the activity of the parent steroid in any way other than to delay its release. Although the lure surrounding various steroid products like testosterone cypionate, Sustanon, Omnadren etc. certainly makes for interesting conversation, realistically it just amounts to misinformation that the athlete would be better off ignoring. Testosterone is testosterone and anyone who is going to tell you one ester form of this (or any) hormone is much better than another one should do a little more research, and a lot less talking.

Acetate: Chemical Structure C2H4O2.
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 fat removal. Again, there is 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.

Propionate: Chemical Structure C3H6O2.
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. Testosterone propionate and methandriol dipropionate (two separate propionate esters attached to the parent steroid methandriol) are popular items.

Phenylpropionate: Chemical Structure C9H10O2.
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.

Isocarpoate: Chemical Structure C6H12O2.
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.

Caproate: Chemical Structure C6H12O2.
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: Chemical Structure C7H14O2.
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 at least weekly to help maintain a uniform blood level.

Cypionate: Chemical Structure C8H14O2.
Also referred to as Cyclopentylpropionic acid, cyclopentylpropionate. Cypionate is a very popular ester here in the U.S., although it is scarcely found outside this region. Its release duration is almost identical to enanthate (10-14 days), and the two are likewise thought to be interchangeable in U.S. medicine. Althletes 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.

Decanoate: Chemical Structure C10H20O2.
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: Chemical Structure C11H20O2.
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: Chemical Structure C11H22O2.
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 idea use of esterified androgens.

Laurate: Chemical structure C12H24O2.
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).
Another ester article:

by Roy Harper

It seems many people know very little about steroid esters. Many people believe it is the ester that determines the anabolic potential for any steroid. But in reality, there is absolutely no difference, in anabolic strength, from one ester to the other. Testosterone suspension is the same as Testosterone cypionate once the cypionate ester has been cleaved off by esterases in your body. Testosterone is testosterone no matter how you look at it. Now before you roll me up in a carpet and throw me over a bridge, I will admit that there is a large difference in how esters affect the release of the steroid. The key is time release (read half-life). Esters essentially delay the release of a steroid. Regardless of whether you injected 500mg of Testosterone suspension or 500mg of Testosterone cypionate, you will end up with approximately 500mg Testosterone in your system (ok, there is going to be slightly less testosterone with the cypionate because of the weight of the ester, but I’ll explain that later). The difference between the two is that all of the 500 mg of testosterone suspension would be available and metabolized within 24 hours, whereas after a week half of the testosterone in the cypionate would be released. Is that it? That's all what esters do? Of course not! In fact the real purpose for esters is to change the properties of the parent drug. As shown above the half-life, can be altered through the use of an ester.

Let's go through some of the details about esters. Steroid molecules are carbon based, as with any earthly organic molecule. The base of the molecule is formed with a chain of carbon molecules. At the 17th position, i.e. the 17th carbon atom, there is a hydroxyl group (OH) that is bonded there. This is where the fun comes in, when this base steroid is hydrolyzed (removing the OH group) an ester can be added here. With the addition of the ester the solubility in oil can be changed, the half-life can be changed, etc. To add to this, the more carbon atoms the ester has the more solubility in oil increases and the half life increases. Therefore, esters such as acetic acid (two carbons) and propionic acid (three carbons) aren't as soluble and have a quick half live. On the other hand, esters such as decanoic acid (ten carbons) and undecanoic acid (eleven carbons) are very soluble in oil and have longer half lives.

Well let's put esters on everything! How about those 17Alpha Alkylated steroids? You know the ones that are orally active. Well, as with esters, there is an extra chemical that is added at the 17th position. What's added is a 17-methyl group. This is what makes winstrol and dianabol great steroids. Without them the liver would metabolize these steroids instantaneously. A 17AA steroid ester without the 17-methyl group would be inactive. A 17AA steroid ester attached with the 17-methyl group would prevent the base steroid from being removed from the ester. Although I've heard rumors that 17AA esters have been made, I highly doubt it's even possible.

And now for the juicy part, how to make your esters at home. Note this is a theoretical discussion and not actual instructions. It would be very dangerous not only in the process of esterfication but also injecting the resulting product. With all that said, first we need to begin with a base steroid. The easiest would be using USP grade powder. Then you would add in one part of anhydrid of the ester you want, to two parts of pyridine. For example you would add in 500mg of cypionic anhydride to 250mg pyridine. Then the base steroid would react within this mixture at ten parts mixture to one part base steroid. Once the reaction has occurred you would then purify the mixture with twenty parts water and one part ether. Decant the water while adding it to another ten parts water. Once complete, simply recrystalize the steroid, and there you have it. A steroid ester made at home. But remember if you aren't a chemist you should not even think of doing this.

Well let’s look at the opposite side of the spectrum. Suppose you want to remove the ester from a steroid ester. Start by dissolving the steroid ester in water. If the ester is already in an oil solution then you better know what the oil is and look it up in the Merck index to figure out how to remove either the oil or steroid ester. Once dissolved in water the ester can be removed. As above you need to use the Merck index to figure it out for each ester. If you got this far then you have your very own base steroid.

You may be thinking to yourself "If this is so complicated, how come our bodies can do it so easily?" Well the answer my friend is invariably, enzymes. Ahh the power of enzymes. Is there anything they can't do? Well looking closer at how our bodies do it, we see that the enzyme esterase is responsible for this process. It follows the same procedure above, technically speaking, and requires water to break the steroid from the ester. But the more oil and the more soluble in oil the steroid ester becomes, the harder it is for esterase to perform its duty. The use of other enzymes to remove the steroid ester from the oil which will lengthen the amount time until the ester is removed. Hence the change in half-life for longer chained esters.

Remember the ester does not determine the anabolic properties of a steroid. With this in mind, please recall that you should consider the timing of injections and the purpose for the steroid. For example Testosterone propionate could be used for a very short cycle. While Nandrolone decanoate would be used in a longer cycle. If you want to determine the half-life of a steroid ester use the following guide:
Ester Number of Carbon Atoms
Formate 1
Acetate 2
Propionate 3
Butyrate 4
Valerate 5
Hexanoate 6
Heptanoate 7
Enanthate 7
Octanoate 8
Cypionate 8
Nonanoate 9
Decanoate 10
Undecanoate 11

If the ester you're looking is not here, simply look on the Internet to find how many carbon atoms there are in the ester. Approximately each carbon atoms is equal to a half-life of 1.5 days. Therefore a decanoate steroid ester would have a half-life of 15 days (11 carbon atoms * 1.5 days constant). In case you're wondering what the half-life is, it's the amount of time before half of the original substance is used. For instance 15 days after an injection of 200mg of deca, 100mg would be left.

Now, you have to remember that the ester is going to add more weight to the molecule. The larger the ester the less base steroid there is going to be in a 100mg steroid ester. You can use the following chart to figure this out:

Chemical Formula

Molecular Weight

Mg of Testosterone
Testosterone (no ester)
C19 H28 O2 288.4 100mg
C2 H2 O 42.1 87.26mg
C3 H4 O 56.1mg 83.72mg
C7 H12 O 112.2mg 71.99mg
C8 H4 O 124.2mg 69.90mg
C10 H18 O 154.3mg 65.15mg

Undecanoate info not availible
*Data Extrapolated from another formula (may not be exact)

Hopefully all of this has educated you in the wonderful world of esters. Never again will you wonder about the difference between acetate and undecanoate.

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