Drugs that suppress the activity of the ovaries and slow the growth of endometrial tissue

Some doctors recommend the long-term use of low-estrogen, high-progestin birth control pills, unless a woman is trying to get pregnant. These pills are deliberately used to lighten or sometimes even stop periods and appear to help keep stray endometrial tissue from growing. Of the drugs used for endometriosis, birth control pills have the mildest side effects.

Drugs that suppress the body's production of estrogen may also be used to control endometriosis. Danazol (Danocrine) is a powerful drug similar to the hormone testosterone. Danazol has been shown to improve symptoms for 89 percent of women who take it and to reduce the size and number of implants. It works by reducing FSH and LH levels. It is taken for six to nine months at a time. However, women who use it may experience side effects including pseudo-menopause, hot flashes, a dry vagina, joint pain, weight gain, depression, irritability, fatigue, and voice changes. In extreme cases, side effects may include masculinization. There is a high rate of recurrent pain after pregnancy for those who conceive after this treatment. In addition, over 30% of these women have some kind of problem with fertility later on. Because of its many serious side effects, Danazol is seldom used these days.

The two most commonly used drugs are derived from gonadotropin-releasing hormone, a naturally occurring brain hormone. They are called gonadotropin-releasing hormone agonists (GnRH-a for short).

These drugs shut down secretion of LH and FSH by overloading the pituitary's production facilities. In effect, the GNRH analogs put an end to ovulation without removing the ovaries. The near menopausal state that results stops menstruation and the growth of endometrial tissue, and reduces the pain of endometriosis. Of course, it also brings with it the problems of estrogen deficiency, ranging from hot flashes and headaches to increased risk of osteoporosis. These problems can be halted by going off these medications, and fertility then appears to be regained.

GNRH analogs can be taken as a nose spray Nafarelin (Synarel), as a daily or monthly injection Leuprolide (Lupron), or as a monthly implant beneath the skin (Zoladex). A course of treatment lasts 6 months.

Nafarelin, available as a nasal spray called Synarel, relieves symptoms and helps shrink endometrial lesions. In a trial involving 247 women treated with nafarefin for six months, 85 percent had their implants shrink or disappear and their symptoms relieved. Six months after treatment, however, symptoms reappeared in half of those who had been helped. Possible side effects are similar to some of the discomforts of menopause, including hot flashes, vaginal dryness, and lighter, less frequent, or no menstruation. Other effects include headaches and nasal irritation.

An injectable drug named leuprolide (Lupron) is similar to nafarelin. Treatment consists of one injection a month for six months. In clinical studies, the effectiveness of leuprolide has been found to be about the same as that of danazol, according to the manufacturer. Potential side effects are similar to those caused by nafarelin.

In addition to pain-relief medications available over-the-counter, a number of prescription products can be used to reduce the pain of endometriosis. These drugs, called nonsteroidal anti-inflammatories include Naprosyn, Feldene, Ponstel, Rufen, Clinoril, Motrin, Nalfon, Dolobid, Meclomen, Tolectin, and Indocin. Narcotic pain-killers such as codeine, oxycodone, meperidine and morphine, as well as narcotics combined with other pain relief drugs, may also be prescribed.