Medroxyprogesterone Acetate

Medroxyprogesterone acetate is a derivative of progesterone and is active by the parenteral and oral routes of administration. It is a white to off-white, odorless crystalline powder, stable in air, melting between 200 and 210°C. It is freely soluble in chloroform, soluble in acetone and in dioxane, sparingly soluble in alcohol and in methanol, slightly soluble in ether, and insoluble in water.

Medroxyprogesterone is a semisynthetic compound that differs in structure from the naturally occurring human hormone progesterone. It is added to estrogen replacement therapy to prevent uterine cancer caused by unopposed estrogen. It is also used to treat absence of menstrual bleeding (amenorrhea) and abnormal menstrual bleeding. Medroxyprogesterone is available alone and in a combination product. An injection product is used for contraception.

Medroxyprogesterone acetate is a hormonal therapy, which is used in the treatment of some cancers. It is a man-made drug that is similar to the female hormone progesterone. Hormones are substances that are produced naturally in the body, where they act as chemical messengers and help control the activity of cells and organs. Medroxyprogesterone acetate is a progestin used to treat menstrual disorders. It may also be used to treat other conditions as determined by your doctor. Progestins lower the risk of estrogen-related cancer of the uterus. Medroxyprogesterone acetate used in combination with estrogen (hormone replacement therapy - HRT) should not be used to prevent heart disease.

The way medroxyprogesterone acetate works is not yet fully understood but it is thought that in some way it interferes with the action of a female hormone, oestrogen. Men produce small amounts of this hormone. Many cancers rely on supplies of specific sex hormones, such as oestrogen, to grow. Cancer cells have proteins called receptors on their surface which the sex hormones attach to. The easiest way to understand the significance of these receptors is to compare the process to that of a lock and key. Under normal circumstances, when the sex hormones come into contact with the receptors they fit into the lock and activate the cancer cells to divide, and the tumour grows. Medroxyprogesterone acetate disrupts this process in some way. It may be that it prevents the cancer cells from maintaining the receptors on their surface, effectively removing the lock. Or it may have a more direct means of destroying cancer cells that has not, as yet, been identified.