Week 4: Reproductive pharmacology: Androgens Flashcards
Stuff not discussed in class
Pharmacologic uses of testosterone
- Anabolic effects
- Androgenic effects (in the treatment of testosterone deficiency
Clinical uses of testosterone
- The primary clinical use of the androgens is for replacement therapy in hypogonadism
- Androgens have also been used to stimulate red blood cell production in certain anemias and to promote weight gain in patients with wasting syndromes (eg AIDS patients)
- The anabolic effects have been exploited illicitly by athletes to increase muscle bulk and strength
Androgen toxicities
- Use of androgens by females results in virilization (hirsutism, enlarged clitoris, deepened voice) and menstrual irregularity
- In women who are pregnant with a female fetus, exogenous androgens can cause virilization of the fetus’ external genitalia
- Excessive doses in men can result in feminization (gynecomastia, testicular shrinkage, infertility) as a result of feedback inhibition of the pituitary and conversion of the exogenous androgens to estrogens
- In both sexes, high doses of anabolic steroids can cause cholestatic jaundice, elevation of liver enzyme levels and possibly hepatocellular carcinoma
List of antiandrogens
- Receptor antagonists (flutamide)
- 5α-reductase inhibitors (finasteride)
- Synthesis inhibitors (ketoconazole)
- Other (GnRH agonist, combined oral contraceptives)
Flutamide MOA
flutamide and related drugs are non-steroidal competitive antagonists of androgen receptors
Flutamide clinical uses
used to decrease the action of endogenous androgens in patients with prostate carcinoma
Spironolactone MOA
A drug that is primarily used as a potassium-sparing diuretic but it also inhibits androgen receptors
Spironolactone clinical uses
Primarily used as a Potassium-sparing diuretic but also inhibits androgen receptors and is used in the treatment of hirsutism in women
5α-reductase inhibitors MOA
- Testosterone is converted to 5α-reductase
- Some tissues, notably prostate cells and hair follicles depend on DHT rather than testosterone for androgenic stimulation
5α-reductase inhibitor prototype
Finasteride
Finasteride MOA
- 5α-reducatase inhibitor
- 5α-reducatase converts testosterone to DHT
- Finasteride inhibits this
Clinical uses of Finasteride
- benign prostatic hyperplasia
- at lower dose: prevent hair loss in men
Finasteride adverse effects
Because the drug does not interfere with the action of testosterone, is is less likely than other antiandorgens to cause impotence, infertility and loss of libido
Inhibitors of steroid synthesis prototype
Ketoconazole
What is ketoconazole?
- an antifungal drug, inhibits gonadal and adrenal steroid synthesis
- The drug has been used to suppress adrenal steroid synthesis in patients with steroid-responsive metastatic prostate cancer
Clinical uses of Ketoconazole
- an antifungal drug, inhibits gonadal and adrenal steroid synthesis
- The drug has been used to suppress adrenal steroid synthesis in patients with steroid-responsive metastatic prostate cancer
GnRH analogs and antagonists as antiandrogens