Pfizer Inc. said on Tuesday it has received U.S. regulatory approval to sell a drug to treat the pain associated with endometriosis, a condition in which tissue from the uterus migrates and implants in other areas of the body.

The injectable drug, depo-subQ provera 104, contains the same active ingredient as the contraceptive Depo-Provera, but in a new formulation.

One of the biggest symptoms of endometriosis is pelvic pain. Pfizer said clinical data shows its drug is as effective in treating pain as Lupron Depot, a common existing treatment, but causes a lower incidence of menopausal symptoms such as hot flashes.