Infertility studies support anastrozole, letrozole.(Gynecology)

LOS ANGELES -- New data from two pilot studies support the use of aromatase inhibitors to promote pregnancy in women with ovulatory dysfunction or unexplained infertility, according to poster presentations at the annual meeting of the Society for Gynecologic Investigation.

In the first randomized study to test anastrozole as an infertility treatment, women who took the aromatase inhibitor before undergoing intrauterine insemination (IUI) had a pregnancy rate comparable overall with those undergoing standard treatment with clomiphene and IUI. Anastrozole cycles appeared to offer an advantage, however, in that they led to more pregnancies in women with polycystic ovary syndrome and generated three times fewer follicles overall.

In the second study, women taking letrozole before undergoing in vitro fertilization (IVF) produced more oocytes and had higher pregnancy rates than those who were treated with a standard protocol of gonadotropins, although the differences between groups were not statistically significant. This study was a randomized feasibility trial in low responders who had failed previous treatments and were scheduled for an aggressive IVF protocol.

Christopher S. Sipe, M.D., lead investigator of the anastrozole study, said in an interview that he believes enough data exist for physicians to start prescribing aromatase inhibitors for infertility patients, but that few will without an indication for infertility from the Food and Drug Administration. "I think you can still use it, but I don't think a lot of people will with the medicolegal aspects in the field," said Dr. Sipe of the department of ob.gyn. at the University of Iowa Hospitals and Clinics, Iowa City.

The anastrozole trial recruited 50 couples from the University of Iowa Infertility Treatment Center. Patients with tubal factor infertility or severe male factor infertility were excluded.

Women were randomized to receive 1 mg of anastrozole or 100 mg of clomiphene citrate on cycle days 3 through 7. All women received intramuscular injections of 75 IU of purified FSH on days 7 through 11.

On day 12, ultrasounds and measurements of serum estradiol were initiated and performed every other day. If needed, FSH injections continued until a follicle greater than 18 mm was observed and the patient received 10,000 U of human chorionic gonadotropin. ...