Testosterone Undecanoate

The Marathon Man Of Testosterone Esters

Put aside the questions of ethics, as well as any arguments of health benefits or health concerns; in the end, steroid use is a pain in the rear- literally. Most anabolic steroid (AAS) users include injectable versions of testosterone, nandrolone and/or some other AAS in their stacks, as injectables are more consistent in maintaining androgenic concentrations, generally less expensive and less toxic.1 AAS are made suitable for injection through a variety of chemical modifications- the most commonly encountered being 17£]-esterification. Esterification is a chemical term that describes the bonding (chemical attachment) of an acid to an alcohol group. In the case of AAS, the esterification describes the attachment of a fatty acid to the hydroxyl (alcohol) group on the 17th carbon.

Was that confusing? It should have been to anyone without some exposure to organic chemistry or those self-educated in the structure of AAS. Many users take AAS chemistry for granted without realizing the drugs are elegantly designed and each has characteristics that make it better or worse for certain uses. In more basic terms, injectable AAS are chemically changed in order to develop a drug that is better suited for clinical use. Most are esterified, which is the term used when a long-chain fatty acid is attached. Pharmaceutical chemists esterify AAS so they release more slowly, allowing the drug to be active for a longer period. In general, the longer the fatty acid attached, the slower the release.2

Esterification has proven to be very beneficial in therapeutic use, as testosterone and related drugs would otherwise be cleared from the system within hours if injected in their normal form. Of course, some athletes competing in drug-tested organizations use this fact to their advantage in order to defeat certain drug screens- they use nonesterified or short-chain testosterone esters (like testosterone acetate), which are quickly flushed from the system. Anti-doping agencies have managed to catch up to this strategy by analyzing testosterone at the atomic level, looking at isotope ratios.3 Again, this is a very sophisticated technique that very few people understand unless they have been fortunate enough to have studied chemistry. For the noncompetitive athlete, or those who compete in organizations that do not test for or ban AAS, longer acting esters offer a number of advantages, including: less fluctuation (highs and lows) of serum (blood) testosterone concentrations, longer intervals between injections and more reliable anabolic response. Of course, there are some disadvantages to long-acting esters, as chemical karma always seems to require some tradeoff. Longer acting esters take longer to reach an anabolic concentration, are slower to clear the system, suppress natural testosterone production longer and contain less active component (testosterone) than short-chain esters by weight- for example, testosterone acetate is 87 percent testosterone, testosterone enanthate is 72 percent testosterone and testosterone undecanoate is 61 percent testosterone. Thus, 200mg of testosterone acetate provides 42 percent more testosterone (174mg) than the same amount of testosterone undecanoate (122mg).

Clearly, use of long-chain esters needs to be limited to long-term use in order to allow therapeutic (or anabolic) levels to accumulate. This is similar to the situation encountered with some familiar with AAS, such as nandrolone decanoate (Deca) and boldenone undecanoate (Equipoise). These AAS do not provide the rapid mass gains seen with orals or short-chain esters (acetate, propionate, etc.), in part because they are long-chain esters. Many users, accustomed to short six-to-eight-week cycles will report dissatisfaction with Deca or Equipoise, especially if they taper, due to the slow release. Post-cycle recovery is also much different with these drugs, as their suppressive effect persists for months in some cases, making it important to properly time hCG, Clomid or other drugs to restore natural testosterone production. Similar experiences can be expected with testosterone undecanoate. Finally, there is also greater difficulty in managing any adverse effect that might arise (irritability, hypomania, anger, aggression, gynecomastia, acne, hair loss, obstruction of the urine stream due to prostate growth, etc.), as elevated androgen levels will persist for weeks.