Androgens

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In applied medicine, testosterone esters (propionate, cypionate, and enantate) and a synthetic analog, methyltestosterone, are widely used. In many tissues, testosterone's androgenic effect depends on the degree to which it is turned into dihydrotestosterone by the enzyme 5-a-reductase in the target tissues. It is believed that all steroids, including testosterone, exhibit their effect by binding with corresponding receptors in target tissues. It has been shown that the affinity to androgenic receptors of the 5-a-dihydrotestosterone is approximately 10 times stronger than that of testosterone. It has also been shown that the binding of androgens with corresponding receptors leads to the synthesis of a few specific proteins in the body, i.e. their use is always accompanied by anabolic action.

A number of synthetic analogs of androgen were made for various reasons, including the goal of prolonging the androgenic effect and for increasing drug absorbance when used via different methods of introduction. Modifying testosterone included esterification of the 17-^-hydroxyl group, and in particular, making testosterone esters, methylation (methyl-testosterone, dromstanolone), demethylation (nandrolone), and adding halogens to the steroid skeleton (fluoximesterone), replacing the cyclohexane ring A of the steroid structure with a tetrahydropyrane ring (oxandrolone), and adding an additional heterocyclic ring to the steroid structure (stanozolol).

Androgens are used for therapy of androgen-deficient conditions such as hypofunction-ing testicles, eunuchism and eunuchoidism, castration, impotence, climacteric conditions, and also for breast and ovarian cancer in women under 60 years.

Testosterone: Testosterone, 17/i-hydroxyandrost-4-ene-3-one (29.1.5), is made in a number of ways from different substances, including cholesterol, although it is most often made from androstenolone acetate. In order to do this, the keto-group at C17 of the steroid system of androstenolone acetate is reduced to a hydroxyl group by either sodium boro-hydride, lithium aluminum hydride, or hydrogen over Raney nickel, all of which result in a 17/i-hydroxy compound. In the given example, reduction by sodium borohydride or hydrogen over Raney nickel leads to the formation of 3/i-acetoxy-5-androsten-17/i-ol (29.1.1). The hydroxyl group resulting from reduction then undergoes acylation by benzoyl chloride in pyridine, which forms a diester (29.1.2). After that, taking into consideration the differences in the acidic region of the two ester groups present in the molecule as well as the long-known fact that 17-hydroxy-group ester derivatives are harder to hydrolyze than 3-hydroxy-group ester derivatives, the acetyl protection of the hydroxyl group at C3 is removed by selective hydrolysis using potassium hydroxide in ethanol, and the resulting alcohol (29.1.3) is oxidized to a ketone (29.1.4) by aluminum isopropylate in the presence of cyclohexanone as a hydrogen acceptor, during which isomerization of the double bond from position C5-C6 to C4-C5 simultaneously takes place. Subsequent hydrolysis of the remaining ester region of the molecule using an alkali gives the desired testosterone (29.1.5) [1-6]. When necessary to convert this into the corresponding ester (propionate, enantate, cypionate, and a few other testosterone esters), the necessary acyla-tion can be accomplished.

Testosterone (esters) are used medicinally for maturation arrest, functional problems in the reproductive system, hypertrophy of the prostate gland, climacteric disorders in men, a few forms of infertility caused by abnormal spermatogenesis, post-castration syndrome, and endocrine impotence. Testosterone is sometimes used to treat women with reproductive organ and breast tumors, climacteric disorders, and when estrogen drugs are counterproductive. When taken orally, testosterone itself is inactive, and therefore it is generally used in the form of carboxylic acid esters (propionate, enantate, cypionate, and a few forms of testosterone esters). Synonyms of this drug are histerone, malogen, menopax, testoral, and others, while synonyms of testosterone esters include andronate, depotest, everon, and many others.

Methyltestosterone: Methyltestosterone, 17/i-hydroxy-17a-methylandrost-4-en-3-one (29.1.7), is also synthesized from androstenolone by reacting it with methylmagnesiumio-dide, forming the corresponding tertiary alcohol (29.1.6), and subsequent oxidation of the hydroxyl group at C3 to a ketone using chromium (VI) oxide. Simultaneous isomerization of the double bond takes place under the reaction conditions, giving the desired methyl-testosterone (29.1.7) [7-10].

Methyltestosterone is a synthetic analog of testosterone that possesses all of the properties of testosterone, exhibiting stimulatory action on the development of male sex organs and secondary sex characteristics, although it is not degraded by enzymes in the gastrointestinal tract, and therefore it can only be taken orally. It is used for the same indications as testosterone for sexual underdevelopment, functional problems of the reproductive system, and the vascular nerve disorders associated with climacteric problems in men. It is also used for dysfunctional uterine bleeding in premenopausal and menopausal women as well as for breast and ovarian cancer. Synonyms of this drug are androral, testoral, oraviron, and others.

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