Generic Name : Mesterolone Mesterolone is a synthetic anabolic-androgenic steroid (AAS) and derivative of dihydrotestosterone (DHT). It is inactivated by 3α-hydroxysteroid dehydrogenase in skeleta muscules so it is considered a weak androgen. It is not a substrate for aromatase so it is not converted into estrogen. Mesterolone demonstrated to have minimal effect on sperm counts and levels of FSH or LH 1,2. Experiments of mesterolone serving as a potential treatment of depression are still undergoing. Male Hypogonadism/Androgen Deficiency: The primary medical use is to treat low testosterone levels in men due to hypogonadism (a condition where the testes produce little or no hormones). This helps restore normal sexual function, mood, and energy levels. Male Infertility: It is used to manage male infertility that stems from low androgen levels, as it can improve sperm count and quality in affected men. INN: Mesterolone CAS No.: 1424-00-6 Molecular formula: C₂₀H₃₂O₂ Molecular weight: ~304.47 g/mol Assay (Potency) Typically 98.0% – 102.0% (on anhydrous basis), depending on pharmacopeial or internal standard