ENDOCRINE DRUGS

Endocrine preparations act in much the same manner as the naturally occurring (endogenous) hormones discussed in Chapter 18. Androgens, normally made by the testes and adrenal glands, are used for male hormone replacement and to treat endometriosis and anemia. Antiandrogens interfere with the production of androgens or with their binding in tissues. They are prescribed for prostate cancer. Estrogens are female hormones, normally produced by the ovaries, that are used for symptoms associated with menopause (estrogen replacement therapy) and to prevent postmenopausal osteoporosis. Aromatase inhibitors also reduce the amount of estrogen (estradiol) in the blood and are effective against breast cancer.

Selective estrogen receptor modulators (SERMs) have estrogen-like effects on bone (increase in bone density) and on lipid metabolism (decrease in cholesterol levels). However, they lack estrogenic effects on uterus and breast tissue. SERMs are used to treat postmenopausal osteoporosis and breast cancer. Tamoxifen and raloxifene are SERMs. Progestins are prescribed for abnormal uterine bleeding caused by hormonal imbalance and, together with estrogen, in hormone replacement therapy and oral contraceptives.

Thyroid hormone is administered when there is a low output of hormone from the thyroid gland. Calcitonin (a thyroid hormone) is used to treat osteoporosis. It increases calcium in the blood and promotes bone deposition. Glucocorticoids (adrenal corticosteroids) are prescribed for reduction of inflammation and a wide range of other disorders, including arthritis, severe skin and allergic conditions, respiratory and blood disorders, gastrointestinal ailments, and malignant conditions. A fragment of human parathyroid hormone (PTH) has been approved for osteoporosis treatment. This agent stimulates new bone formation. Growth hormone release–inhibiting factor (somatostatin) can be manufactured and given to treat gastrointestinal symptoms associated with acromegaly and other tumors. Examples of endocrine drugs are given below:

ANDROGENS

   fluoxymesterone (Halotestin)

   methyltestosterone (Virilon)