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Andriol Testosterone Undecanoate

Pharmaceutical Name: Testosterone (with undecanoate ester)
Chemical structure: androsta-4-en-3-one,17b-ol
Chemical Formula: C19 H28 O2
Molecular weight of base: 288.429
Molecular weight of ester: 186.2936
Melting Point: 155 Celsius
Active Life: 8-12 hours
Anabolic/Androgenic Ratio: 100/100

Testosterone undecanoate is another compound that has attempted to provide a viable alternative to injectables for testosterone replacement or supplementation. While methyltestosterone was the first attempt at doing this, testosterone undecanoate has tried to solve the major hindrance to long term use of methyltestosterone, namely Hepatoxicity due to it being 17 alpha alkylated.

Testosterone undecanoate has eliminated the need to alter the compound so that it can survive the first pass through the liver and remain effective by skipping this step all together. This accomplished by having the structure of the compound able to be absorbed through the small intestine and lymphatic system (1). This is possible due to the high fat solubility that the undecanoate ester provides, as well as the fact that the testosterone is combined with oil. By bypassing the liver on the first pass, this negates the need for altering the compound in anyway to ensure that it remains active and therefore no additional stress is placed on the liver.

Testosterone undecanoate comes in capsules. These capsules each contain 40 milligrams of the compound which is based in oil, oleic acid, castor oil and propylene glycol laurate being the most common used. When the ester weight of the undecanoate ester is subtracted from the weight of the compound, it leaves 25 milligrams of testosterone per capsule. Now obviously to reach an anabolic effect most users will need to use multiple capsules at once, and run these throughout the day. Due to the active life of the compound being eight to 12 hours, as well as the fact that testosterone levels peak within two hours of administration of the drug, users would be well served to take their capsules at least every 3-4 hours when awake if they hope to acheive any anabolic effect from the compound. This will maintain a relatively stable blood concentration of the compound.

The amount of the drug that enters a user's blood stream is dependent upon the ability of that user's lymphatic system to absorb the compound. This can vary quite dramatically from user to user (2). For this reason it is hard to tell exactly how much of the compound is entering the system of an individual without taking blood samples at specific times to test for this. For most users, it will be a guessing game as to how much testosterone undecanoate is actually being absorbed and "active". This is one of the reasons why it is not considered a complete replacement for injectable compounds.

So with the fact that testosterone undecanoate is not a reliable method of getting exact amounts of testosterone in a user's system, as well as the frequent dosing schedule that must be adhered to, it should also be noted that it is one of, if not the most, expensive form of testosterone available for use. This would make it cost prohibitive for those users looking to administer large amounts of testosterone, or those that require specific amounts of the compound be in their systems. Without utilizing blood tests, there is no way for a user to know exactly how much of the drug is actually being absorbed. For these reasons, the use of testosterone undecanoate is rather limited to rather particular circumstances. It should not be seen as a replacement for injectable versions of testosterone.

One of the theories of why it may be less effective than the injectable version of testosterone is that it may not actually bypass the liver. This would cause the majority of the drug to be broken down by the liver, leaving very little of it left to circulate in the body. However the pharmaceutical company that produces the only currently commercial form of testosterone undecanoate, Andriol produced by Organon, maintains that it does not. If this is true, than it only leaves the theory that individuals' lymphatic systems have different rates of absorption of the compound, and therefore not all of the compound will enter a user's system. This could account for the varied results with testosterone undecanoate, as well as the fact that anecdotally nearly all users report that their gains using the drug are less than spectacular. Only very modest gains in muscle mass and strength are reported by most, even at relatively high doses. Seemingly testosterone undecanoate should not be relied upon in most circumstances if one wishes to see any significant anabolic or androgenic effects.

Use/Dosing of Andriol Testosterone Undecanoate

Like any testosterone, the dosages administered by both male and female users vary quite widely. In the case of testosterone undecanoate it is usually the price and/or the general characteristics of the compound that limit the amount that a user would be willing to use. As for a dosing schedule, as stated earlier, due to the short active life of the compound and the fact that blood levels of the drug peak within two hours of administration users would be well served to split their doses throughout the day to roughly every three to four hours. This should provide a fairly stable concentration of the drug circulating.

Like testosterone in general, this compound can be run safely for extremely lengthy periods of time (3). Due to it not being 17 alpha alkylated like most other oral anabolic steroids there are no increased concerns with Hepatoxicity either. Medically it can be prescribed for testosterone replacement therapy, which should speak to its safety for long term use.

Also like the other testosterone compounds, it can be stacked with most other compounds. However due to the unreliable absorption rates, users should use caution when administering it with other anabolic steroids. If absorption of the testosterone undecanoate is not very efficient, this could lead to low testosterone levels due to suppression of the natural testosterone production in users. This could result in sexual dysfunction and/or a loss of libido in some individuals depending on the compounds that they are using.

For the most part it is recommended that users take their doses with meals, as this will aid with lymphatic absorption. This is due to the improved environment in the small intestine when gastrointestinal secretions such as bile are present. However depending on the dosing schedule of the user this may not always be possible.

Risks/Side Effects of using Andriol Testosterone Undecanoate

Since testosterone undecanoate is indeed simply another form of testosterone, the side effects associated with it are for the most part those commonly encountered with any type of testosterone compound (2). For more specific information about these, including those that may effect women, see the testosterone enanthate profile in this forum. In this section the side effects, and the characteristics of them, that are unique to testosterone undecanoate alone will be dealt with.

Due to the fact that testosterone undecanoate bypasses the liver completely, there are no issues concerning Hepatoxicity. As well due to its short active life, women who experiment with testosterone could find it one of the more appealing options. This is because it will quickly clear a user???s system if severe side effects occur and one has to cease administration of the drug immediately. However, risks of virilizing symptoms developing are still very real.

No other specific side effects are associated with testosterone undecanoate other than those that are commonly found with using any type of testosterone compound. It appears that the drug reacts the same way as other drugs, effecting cholesterol (4), hypothalamic-pituitary-testicular axis, and other functions in the body. There are some studies that seemingly indicate that the compound can actually improve users' blood pressure (5), as well as not effecting the prostate to any great degree. However, like most studies, these conclusions should be viewed not as absolutes.

So due to the fact that testosterone undecanoate is simply another form of testosterone and side effects with its use would be similar to use of any testosterone compound, refer to the Risks/Side Effects section of the Testosterone Enanthate profile in this forum for more specific details of the side effects of testosterone use.


1. Horst HJ, Erdmann T. Recovery of free androgens in the rat prostate in vivo and in vitro after treatment with orally active testosterone undecanoate (TU). Horm Metab Res. 1980 Oct;12(10):541-5

2. Hong JH, Ahn TY. Oral testosterone replacement in Korean patients with PADAM. Aging Male. 2002 Mar;5(1):52-6

3. Gregory JW, Greene SA, Thompson J, Scrimgeour CM, Rennie MJ. Effects of oral testosterone undecanoate on growth, body composition, strength and energy expenditure of adolescent boys. Clin Endocrinol (Oxf). 1992 Sep;37(3):207-13

4. Wu S, Weng X. Therapeutic effect of andriol on serum lipids and apolipoproteins in elderly male coronary heart disease patients. Chin Med Sci J. 1992 Sep;7(3):137-41

5. Li JY, Zhu JC, Dou JT, Bai WJ, Deng SM, Li M, Huang W, Jin H. Effects of androgen supplementation therapy on partial androgen deficiency in the aging male: a preliminary study. Aging Male. 2002 Mar;5(1):47-5

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