Sex hormones are produced by the gonads and inner layer of the cortex of the adrenal medulla. The synthesis and release of the hormones are controlled by the anterior pituitary (luteinizing hormone [LH] and follicle-stimulating hormone [FSH]) and the hypothalamus (gonadotropin-releasing hormone, GnRH). Therefore, we are including in this chapter the actual sex steroids, but also GnRH agonists and antagonists.
|Estrogens ||Antiestrogens |
|DIETHYLSTILBESTROL ||CLOMIPHENE |
|ESTRADIOL ||TAMOXIFEN |
|estriol ||RALOXIFENE |
|estrone ||toremifene |
|ethinyl estradiol || |
|mestranol || |
|quinestrol || |
|Progestins ||Antiprogestins |
|PROGESTERONE ||MIFEPRISTONE |
|hydroxyprogesterone || |
|medroxyprogesterone || |
|megestrol || |
|norethindrone || |
|norgestrel || |
|levonorgestrel || |
|Androgens ||Antiandrogens |
|TESTOSTERONE ||dutasteride (5α-reductase inhibitors) |
|(several preparations) ||FINASTERIDE |
|fluoxymesterone ||flutamide (receptor antagonist) |
|methyltestosterone ||cyproterone acetate |
|testolactone ||nilutamide |
First, compare these drug names to those in your textbook or class handouts. The androgens listed here are only the androgenic steroids. I have not included the agents used primarily as anabolic agents. Look at each name and decide whether you recognize it for what it is. (That is, do you know that norgestrel is a progestin?) Put those you are not sure of in your list for name recognition. The rest of this is easy, especially if you remember your endocrine physiology (Figure 37–1).
This is a very simplified scheme to remind you of the regulation of the sex steroids. There are additional positive and negative feedback mechanisms to the pituitary. GnRH is a gonodotropin-releasing hormone, which is sometimes called LH-RH (leutinizing hormone-releasing hormone).
As with the glucocorticoids, the sex steroids bind to specific intracellular receptors that are nuclear transcription factors.
The major estrogens produced by the body are estradiol, estrone, and estriol.
The ovary is the primary source of estradiol. Estrone and estriol are metabolites of estradiol, courtesy of the liver.
The most common use of estrogens is in oral contraceptives.
Estrogen therapy combined with progestins is used to block ovulation and prevent pregnancy. In postmenopausal women, estrogens can be used to reduce the symptoms of menopause and osteoporosis. Hormone replacement therapies can slow bone loss, but cannot reverse existing deficits. However, there is now evidence that the risks of estrogen-replacement therapy may outweigh the benefits.
The most common side effects of estrogens are nausea and vomiting.
Estrogens can also cause breast tenderness, endometrial hyperplasia, hyperpigmentation, edema (sodium and water retention), and weight gain.
DIETHYLSTILBESTROL (a nonsteroid molecule) has been associated with cervical and vaginal carcinoma in daughters of women who took the drug during pregnancy.
There are two important groups of drugs that antagonize the action of estrogen—the SERMS and clomiphene.