Androgens, Anabolic Steroids & Antiandrogens

Androgens, Anabolic Steroids & Antiandrogens

1. Definition & overview

• Androgens are substances that cause development and maintenance of male secondary sex characters — defined historically as agents that produce these changes in the castrated male; testosterone is the principal natural androgen in both sexes (G&G 14e Ch.49, pp.991–2; KDT 8e Ch.21, p.320).
• That the testes are responsible for male characters has been known since prehistoric times; the endocrine function of the testis was established by Berthold in 1849; testosterone was isolated, structurally characterised, and synthetically prepared by 1935 (KDT 8e Ch.21, p.320).
• In men, Leydig (interstitial) cells synthesise the majority of testosterone; in women, testosterone is also the principal androgen, synthesised in the corpus luteum and adrenal cortex by similar pathways (G&G 14e Ch.49, p.991).
• Daily testosterone production: adult male ~5–12 mg/day (KDT) / ~8–10 mg/day (Padmaja, Katzung); ~95% from Leydig cells, ~5% from adrenals (Katzung 16e Ch.40, p.777). In women, ovary + adrenal-derived testosterone amounts to ~0.25–0.5 mg/day (KDT 8e Ch.21, p.321).
• Anabolic steroids are synthetic androgens engineered for supposedly higher anabolic and lower androgenic activity — but the dissociation is modest in animals and minimal in humans; "for all practical purposes, they are androgens" (KDT 8e Ch.21, p.324; Katzung 16e Ch.40, p.778).
• The topic spans four pharmacological families: (i) androgens / anabolic steroids (agonists), (ii) antiandrogens (AR antagonists, synthesis inhibitors, 5α-reductase inhibitors), (iii) drugs for erectile dysfunction (PDE5 inhibitors and intracavernosal agents), and (iv) male contraceptives (KDT 8e Ch.21, pp.320–9; Padmaja 7e Ch.41, p.502).
• CBME competency mapping: PH 1.37 — describe mechanisms of action, types, doses, side effects, indications and contraindications of sex hormones, their analogues and anterior pituitary hormones (Padmaja 7e Ch.41, p.500).