2 - The Clinical Pharmacology of Oestrogens and Progestagens

Abstract

This chapter discusses the clinical pharmacology of oestrogens and progestagens. Oestrogens are the principal functional hormones produced by the ovarian follicles. They are trophic hormones that play a part in growth and development of the non-pregnant woman, and have a specific function in promoting the development of the female genitalia and secondary sexual characteristics. Cyclical increases in oestrogen production by the ovary are involved in the processes of ovulation and of the menstrual cycle. Oestrogens have an anabolic action, favoring retention of nitrogen, calcium, and phosphorus. Under oestrogen influence, the pelvic blood supply increases, the uterus grows, and the vessels, glands, and connective tissue of the endometrium proliferate. Oestrogen administration produces a proliferative endometrium and inhibits ovulation. The chapter also discusses that progesterone is a naturally occurring steroid hormone, which is produced by the corpus luteum of the ovary, and the adrenal cortex, and during pregnancy by the placenta. Two of its main functions are the maintenance of a secretory endometrium during the post-ovulatory phase of the menstrual cycle and of a decidual reaction in the endometrium during pregnancy. Progesterone has a direct inhibitory effect on the secretion of gonadotropin-releasing factors, and hence, on release of luteinizing hormone, and to a lesser extent, follicle stimulating hormone.