Methenolone enanthate, known by the brand names Primobolan Depot and Nibal Injection, is a type of steroid medicine mainly used to treat anaemia caused by bone marrow problems. It is given by injection into muscle. The biological half-life of metenolone enanthate is reported to be about 10.5 days by intramuscular injection.
As a derivative of DHT, metenolone, the active form of metenolone enanthate, is not aromatised and so has no propensity for producing oestrogenic side effects like gynaecomastia. As an AAS, metenolone enanthate is antigonadotropic and can suppress the hypothalamic–pituitary–gonadal axis and produce reversible hypogonadism and infertility.
Side effects of metenolone enanthate include symptoms of masculinisation like acne, increased hair growth, voice changes, and increased sexual desire. The drug is a synthetic androgen and anabolic steroid and hence is an agonist of the androgen receptor (AR), the biological target of androgens like testosterone and dihydrotestosterone (DHT). It has moderate anabolic effects and weak androgenic effects, as well as no oestrogenic effects or risk of liver damage. Metenolone enanthate is a metenolone ester and a long-lasting prodrug of metenolone in the body.
Metenolone enanthate was introduced for medical use in 1962. In addition to its medical use, metenolone enanthate is used to improve physique and performance. The drug is a controlled substance in many countries, and so non-medical use is generally illicit. It remains marketed for medical use only in a few countries, such as Spain and Turkey.
