NETA, acetic acid ester of norethindrone, norethindrone acetate
Norethisterone acetate (abbreviated as NETA), or norethindrone acetate, is a progestin which is used in hormone replacement therapy, and to treat gynecological disorders, especially adenomyosis (the inner lining of the uterus breaks through the muscle wall of the uterus) and endometriosis (endometrial cells are found growing outside of the uterus). NETA is also used as a hormonal contraceptive in combination with estrogen, in the treatment of gynecological disorders such as abnormal uterine bleeding.
It causes a hypoestrogenism (low level of estrogen in bloodstream) by suppressing hormones that stimulate the gonads, or sex glands, to carry out their reproductive or endocrine functions), inhibiting ovulation, and developing amenorrhea (the absence of a menstrual period in a woman of reproductive age) with eventual partial or complete wasting of inner layer of the uterus (endometrial atrophy).
NETA is a prodrug of norethisterone in the body.Upon oral ingestion, it is rapidly converted into norethisterone by esterases during intestinal and first-pass hepatic metabolism. Hence, as a prodrug of norethisterone, NETA has essentially the same effects, acting as a potent progestogen with additional weak androgenic and estrogenic activity.
Norethisterone acetate offers various advantages for the long-term treatment of endometriosis. Early studies showed that NETA was effective in reducing chronic pelvic pain in women with laparoscopically confirmed endometriosis. It allows good control of uterine bleeding; it has positive effect on calcium metabolism and no negative effects on the lipoprotein metabolism at low dosages.
In women with rectovaginal lesions or colorectal endometriosis, NETA at low dosage should be preferred.
NETA has been reported to be effective in the treatment of endometriosis. NETA as a medical management of adenomyosis is a novel therapy. However, significant breakthrough bleeding is reported in patients of endometriosis being treated continuously with NETA.