methyltestosterone

Methyltestosterone, or 17α-methyltestosterone, is a synthetic androgen and anabolic steroid (AAS). It is a 17α-alkylated derivative of testosterone designed for oral administration. It has been used medically as an androgen replacement therapy in men with testosterone deficiency when injections are unsuitable; it has also been used in the past to treat certain forms of breast cancer in women and other conditions responsive to androgens, though its use is limited by safety concerns and the availability of alternatives.

Pharmacology and mechanism of action: Methyltestosterone binds to androgen receptors, promoting protein synthesis and the development of male secondary sexual characteristics. When taken orally, it undergoes extensive hepatic metabolism, and the 17α-alkyl group increases liver exposure, which raises the risk of hepatotoxicity. It is a controlled substance in many jurisdictions due to potential misuse as an anabolic agent.

Regulation and availability: In the United States, methyltestosterone is classified as a Schedule III controlled substance because of abuse and dependence potential. In many countries it remains available only by prescription, but its use is generally less common than other testosterone formulations because of safety concerns, particularly liver toxicity.

Adverse effects and safety considerations: Side effects include virilization in women and children, acne, edema, changes in libido, and gynecomastia in men. It can suppress the hypothalamic-pituitary-gonadal axis, leading to testicular atrophy and reduced fertility. Hepatotoxic effects can include cholestasis, peliosis hepatis, and liver tumors. It is contraindicated in pregnancy and in men with prostate cancer or certain breast cancers.