Chapter 39: Sex Steroids

ORGANIZATION OF CLASS

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 include in this chapter the actual sex steroids, but also GnRH agonists and antagonists.

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 physiology.

As with the glucocorticoids, the sex steroids bind to specific intracellular receptors that are nuclear transcription factors.

ESTROGENS

The ovary is the primary source of estradiol. Estrone and estriol are metabolites of estradiol, courtesy of the liver.

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.

Estrogens can also cause breast tenderness, endometrial hyperplasia, hyperpigmentation, edema (sodium and water retention), and weight gain.

ANTIESTROGENS

There are two important groups of drugs that antagonize the action of estrogen—the selective estrogen receptor modulators (SERMs) and clomiphene.

Tamoxifen and toremifene are used in the prevention and treatment of breast cancer that has estrogen receptors. These drugs are antagonists ...