Testosterone

Testosterone is a steroid hormone which is secreted by the testes of male. It is responsible for the proper development of male sexual characteristics. It also maintains muscle bulk, adequate levels of red blood cells, bone density, sense of well-being, and sexual and reproductive function. Small amounts are also produced by the adrenal glands.

In men, testosterone plays a key role in the development of male reproductive tissues such as the testis and prostate as well as promoting secondary sexual characteristics such as increased muscle and bone mass and hair growth. In addition, testosterone is essential for health and well-being as well as preventing osteoporosis.

On average, an adult human male body produces about ten times more testosterone than an adult human female body, but females are, from a behavioral perspective rather than from an anatomical or biological perspective, more sensitive to the hormone. However, the overall ranges for male and female are very wide, such that the ranges actually overlap at the low end and high end respectively.

Progestin

Progestin is a synthetic form of the hormone progesterone. The two most frequent uses of progestins are for hormonal contraception (either alone or with an estrogen), and to prevent endometrial hyperplasia from unopposed estrogen in hormone replacement therapy. Progestins are also used to treat secondary amenorrhea, dysfunctional uterine bleeding and endometriosis, and as palliative treatment of endometrial cancer, renal cell carcinoma, breast cancer, and prostate cancer. High dose megestrol acetate is used to treat anorexia, cachexia and AIDS-related wasting. Progesterone, or sometimes the progestin dydrogesterone or 17a-hydroxyprogesterone caproate, is used for luteal support in IVF protocols, questionably for treatment of recurrent pregnancy loss, and for prevention of preterm birth in pregnant women with a history of at least one spontaneous preterm birth.

Scientists have discovered that the most effective method of contraception was with a combination of estrogen and progestin. This can be done in a monophasic, biphasic, or in a triphasic manner. In the monophasic method, both an estrogen and a progestin are administered for 20 or 21 days and stopped for a 7 or 8 day period that includes the 5 day menstrual period. Sometimes, a 28 day regimen is used that includes 6 or 7 inert tablets. Newer biphasic and triphasic methods are now used to more closely simulate the normal menstrual cycle. Yet another method is to administer a small dose of progestin only (no estrogen) in order to decrease certain risks associated with administering estrogen, but a major side effect is irregular bleeding that is usually observed during the first 18 months of such therapy.