July 23, 2014
Letrozole Increases Birth Rates for Women With Polycystic Ovary Syndrome

Hershey, PA—While clomiphine citrate has been the standard treatment for decades to stimulate ovulation in women with polycystic ovary syndrome (PCOS), the drug letrozole results in higher birth rates, according to a new nationwide study.

The study, led by clinicians from Penn State University and published recently in the New England Journal of Medicine, involved more than 20 researchers from around the country.

“Clomiphine has its drawbacks,” said lead author Richard Legro, MD, Penn State professor of obstetrics and gynecology. “It's only 22% successful with up to six cycles of treatment in producing a successful birth. It has a high multiple-pregnancy rate in comparison to unassisted conception, and it has side effects including hot flashes and mood changes.”

The article’s background section notes that PCOS affects 5%–10% of reproductive-aged women and is the most common cause of female infertility. The condition creates excessive levels of the hormone androgen, causing infrequent periods, the development of small cysts on the ovaries, and problems with conception.

Letrozole, which is in a class of drug that blocks estrogen production, is FDA-approved for the adjuvant treatment of postmenopausal women with hormone receptor–positive early breast cancer.

For the study, researchers focused on 750 infertile women with PCOS between 18 and 40 years old who wanted to conceive. Randomly assigned to either clomiphene or letrozole, participants took the medications for up to five cycles, with increasing dosage each cycle.

The group receiving letrozole had a higher rate of live births, 27.5%, than those on clomiphene, 19.1%, with ovulation rates significantly higher with letrozole than with clomiphene at each monthly visit.

In addition, women taking letrozole had fewer twin pregnancies, 3.9%, than those on clomiphene, 6.9%. Both drugs had their downsides: Clomiphene was associated with a significantly higher incidence of hot flashes, while letrozole was linked to significantly higher incidence of fatigue and dizziness.

Birth defects were no more common than in women who conceive without treatment, although there were four major congenital anomalies in the letrozole group versus one in the clomiphene group (P = 0.65).

Study authors are calling for further research with a larger number of infants to clarify the safety of letrozole.

U.S. Pharmacist Social Connect