The US Food and Drug Administration has approved a new medication for women who experience the pain of endometriosis. The drug is known as depo-subQ provera 104 (medroxyprogesterone acetate), the first new treatment option for the condition in more than a decade, according to its manufacturer, Pfizer.
"The availability of depo-subQ provera 104 is good news for the millions of women who suffer from pain caused by endometriosis, a condition that tends to worsen over time if not treated," said Ray Urbanski, MD, PhD, medical director of Pfizer, in a statement.
The Pain of Endometriosis
Endometriosis is a very common gynecological condition, affecting at least 5-and-a-half million women in North America, according to one estimate. The condition occurs when tissue normally found on the lining of the uterus instead grows in areas where it is not supposed to outside the uterus. These areas might include the ovaries, behind the uterus, on the tissues that hold the uterus in place, or on the bowels or bladder.
Symptoms include very painful cramps or periods, heavy periods, chronic pelvic pain, intestinal pain, pain during or after sex, and infertility. Pain, in fact, is one of the most common symptoms of the disease.1
It's estimated that up to 40 percent of women with endometriosis become infertile as a result.
A New Option
Depo-subQ provera 104 is expected to be available to patients beginning in May, said Daniel Watts, senior manager of Media Relations at Pfizer. The company claims the new medication is just as effective as Lupron Depot (leuprolide acetate), a currently available medicine prescribed for endometriosis pain made by TAP Pharmaceutical Products, but causes fewer hot flashes and less bone mineral density loss.
It's made with the same active ingredient as Pfizer's Depo-Provera Contraceptive Injection—medroxyprogesterone acetate—a derivative of progesterone, which blocks the production of gonadotropins in the body, which in turn, prevents follicles from maturing, as well as ovulation. The result is halted menstruation and thinning of the uterine lining, which then halts the growth of endometriotic lesions, relieving their associated pain.2
While this medication can be effective for women experiencing endometriosis-related pain, it's not indicated for women hoping to become pregnant in the future. Since the medication acts as a contraceptive, women planning pregnancy should first speak with their physicians, Watts advised. "The guidance is that if you're planning on getting pregnant in the immediate future, it's not appropriate because [the medication] is long-term birth control," he said.
Scientific Evidence
Pfizer says the approval of depo-subQ provera 104 hinged on the results of two studies—one, involving 274 patients and the other including nearly 300 women— comparing the medication to Lupron.3 Each patient was administered depo-subQ provera 104 or Lupron for a total of six months. They were then followed up for one year, and were asked to report their symptom relief, such as dysmenorrhea (lack of menstruation), dyspareunia (pain during intercourse), and pelvic pain. Signs of pelvic pain were also evaluated, such as pelvic tenderness.
The study found that depo-subQ provera 104 was equally effective to Lupron for all types of endometriosis-related pain, including pelvic pain, pelvic tenderness, painful periods or intercourse, and hardening and/or thickening of uterine tissue. However, in both studies more patients taking Lupron reported symptoms associated with endometriosis than those taking Depo-subQ-provera 104, Pfizer stated.
Differences in Bone Loss
At the end of the trial of 274 women, those given Lupron showed "significant decreases" in bone mineral density of the femur (thigh bone) and lumbar spine, but those taking depo-subQ provera 104 did not. However, Pfizer says bone loss is still possible with depo-subQ provera use, since it blocks the production of estrogen, a hormone that, when no longer produced, accelerates bone loss.4
The medicine is designed as an injection to be taken every 12 to 14 weeks.
Other side effects discovered in clinical trials included irregular menstrual bleeding, typically followed by amenorrhea.
Depo-subQ provera 104 was initially approved by the FDA in December as a contraceptive. The medication is more effective than the original Depo-Provera contraceptive, but with 30% less hormone, according to Pfizer.
1. National Institute of Child Health and Human Development. National Institutes of Health (NIH). Fast Facts About Endometriosis. Available at: http://www.nichd.nih.gov/publications/pubs/endometriosis/index.htm. Accessed March 29, 2005.
2. Depo-SubQ Provera 104. Medroxyprogesterone acetate injectable suspension. 104 mg/0.65 mL. Prescribing Information. Available at: http://www.pfizer.com/download/uspi_depo_subq_provera.pdf. Accessed March 29, 2005.
3. Pfizer NDA.
4. Mayo Foundation for Medical Education and Research. Height Loss: When to be Concerned. Available at: http://www.mayoclinic.com/invoke.cfm?id=HQ00826. Accessed March 29, 2005.
John Martin is a long-time health journalist and an editor for Priority Healthcare. His credits include coverage of health news for the website of Fox Television's The Health Network, and articles for the New York Post and other consumer and trade publications.
