When it interacts with the aromatase enzyme it does not form any estrogens. It is used by people who are very succeptible to estrogenic side effects, having lower estrogenic properties than Nandrolone. Methenolone is available as an injection or as an oral(Primobolan 100). The injection is naturally regarded as having a higher bioavailability. Its an enanthate ester which is quite long-acting. Because it by-passes hepatic breakdown on the first pass, it also has a higher survival rate. The tablets are in a short-lived acetate form. Methenolone is not 17-alpha-alkylated, but 1-methylated for oral bioavailability. This reduces the stress on the liver, but also the availability. It is considered one of the safer steroids, meaning it has a very little side effects. Methenolone has no estrogenic side effects, and its effects on cholesterol levels are minimal. In doses of 200 mg or less (intramuscular) blood pressure is rarely altered.
Possibly one of the safer anabolic steroids for females due to very low virilization effects in short-term usage. Of course, this is not a blanket-statement and individual results (dependent on doses and tolereance) will vary.
Methenolone is also not overly suppressive of the HPTA axis, although how suppressive is debatable. For this reason, many bodybuilders use it in between steroid cycles during their “off-time” to help maintain their gains and strength. The long term safety of such a practice possibly dangerous and can lead to permanent suppression of the HPTA.
Arnold Schwarzenegger is rumored to have introduced methenolone to the US bodybuilding community.