nafarelin, Synarel

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GENERIC NAME: nafarelin

BRAND NAME: Synarel

DRUG CLASS AND MECHANISM: Nafarelin is a synthetic (man-made) protein that blocks the effects of the natural gonadotropin-releasing hormone (GnRH), a hormone that regulates the output of gonadotropins (a class of hormones) by the pituitary gland (a small gland located at the base of the brain). Gonadotropins (follicle stimulating hormone or FSH and luteinizing hormone or LH) are hormones that cause estrogen production by the ovaries. When nafarelin (known scientifically as a GnRH analog) is administered continuously to women in their reproductive years, the pituitary output of FSH, LH, and the production of estrogen by the ovaries are suppressed. Suppression of estrogen production causes menstruation to stop, resulting in a temporary (but reversible) state of "menopause." This temporary  state of menopause results in shrinkage of the lining of the uterus, known as the endometrium.

Endometriosis is a condition whereby the cells that normally form the endometrium inside of the uterus are instead found outside of the uterus. These abnormally located cells (called endometrial implants) are most commonly found on the ovaries, Fallopian tubes, outer surfaces of the uterus or intestines, and on the surface lining of the pelvic cavity. Like the normal endometrium, implants respond to the hormones of the menstrual cycle, i.e., they build up during the month, then break down and bleed during menstruation. However, unlike normal endometrium, the implants bleed internally. (blood from implants cannot exit the body like blood from the uterus can.) The internal bleeding, followed by tissue inflammation and subsequent scarring, is believed to be responsible for the symptoms of pain and infertility in women with endometriosis. Nafarelin has been found to be effective in relieving the pain of endometriosis and shrinking the endometrial implants.

Medically Reviewed by a Doctor on 3/22/2013



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