and hence increase in free unbound testosterone caused by methyltestosterone, androgenic effects may be greater than reflected merely by methyltestosterone levels. Distribution Methyltestosterone is highly protein-bound, by approximately 98%. The medication has low but significant affinity for human serum sex hormone-binding globulin (SHBG), about 25% of that of testosterone and 5% of that of DHT. Metabolism The biological half-life of methyltestosterone is approximately 3 hours (range 2.5–3.5 hours). The duration of action of methyltestosterone is said to be 1 to 3 days, and is described as relatively short among AAS. Excretion Methyltestosterone is excreted 90% in the urine as conjugates and other metabolites, and 6% in feces. Chemistry Methyltestosterone, also known as 17α-methyltestosterone or as 17α-methylandrost-4-en-17β-ol-3-one, is a synthetic, 17α-alkylated androstane steroid and a derivative of testosterone differing from it only in the presence of a methyl group at the C17α position. Close synthetic relatives of methyltestosterone include metandienone (17α-methyl-δ1-testosterone) and fluoxymesterone (9α-fluoro-11β-hydroxy-17α-methyltestosterone). Derivatives Methyltestosterone and ethyltestosterone (17α-ethyltestosterone) are the parent structures of all 17α-alkylated AAS. Major 17α-alkylated AAS include the testosterone derivatives fluoxymesterone, metandienone (methandrostenolone), and methyltestosterone and the DHT derivatives oxandrolone, oxymetholone, and stanozolol. Synthesis A chemical synthesis of methyltestosterone from dehydroepiandrosterone (DHEA) with methandriol as an intermediate proceeds as follows: History Methyltestosterone was first synthesized in 1935 along with methandriol and mestanolone. It was the second synthetic AAS to be developed, following mesterolone (1α-methyl-DHT) in 1934, and was the first 17α-alkylated AAS to be synthesized. The drug was introduced for medical use in 1936. Society and culture Generic names Methyltestosterone is the , , , , and of the drug and its generic name in English and Japanese, while méthyltestostérone is its and French name and metiltestosterone is its and Italian name. The generic name of the drug is methyltestosterone in Latin, methyltestosteron in German, and metiltestosterona in Spanish. Methyltestosterone is also known by its former developmental code name NSC-9701. Brand names Brand names under which methyltestosterone is or has been marketed for medical use include Afro, Agovirin, Android, Androral, Mesteron, Metandren, Methitest, Methyltestosterone, Methyl Testosterone, Oraviron, Oreton, Oreton Methyl, Testormon, Testovis, Testred, and Virilon, among others. With an estrogen Methyltestosterone is available at a low-dose in combination with esterified estrogens for the treatment of menopausal symptoms like hot flashes in women under the brand names Covaryx, Essian, Estratest, Menogen, and Syntest. Availability United States Although it is not commonly used, methyltestosterone is one of the few