Aromatase Inhibitor Useful to Induce Ovulation

TUESDAY, Nov. 28 (HealthDay News) -- The aromatase inhibitor letrozole is a useful alternative to clomiphene citrate to induce ovulation in women with polycystic ovary syndrome (PCOS), according to a study published in the November issue of Fertility and Sterility.

Ulku Bayar, M.D., of Zonguldak Karaelmas University in Zonguldak, Turkey, and colleagues randomized 74 infertile women with PCOS to receive either 2.5 mg/day of letrozole or 100 mg/day of clomiphene citrate on days three to seven of menses.

In the letrozole group, ovulation occurred in 65.7 percent of the 99 cycles, and among the clomiphene citrate group it occurred in 74.7 percent of the 95 cycles. There was a statistically significant difference in median serum E2 concentrations between the two groups on the day of hCG administration: 189 pg/mL for the letrozole group and 386 pg/mL for the clomiphene citrate group. The median serum E2 concentrations per follicle sized above 15 mm in diameter on the day of hCG administration was 160 pg/mL and 281 pg/mL for the letrozole and clomiphene citrate groups, respectively.

Pregnancy occurred in nine of the letrozole cycles (9.1 percent) and seven of the clomiphene citrate cycles (7.4 percent), which was statistically insignificant. "The use of letrozole as a first-line ovulation-induction agent in PCOS patients may be favored because of the beneficial effects in terms of fewer mature follicles (decrease in multiple-pregnancy rate) and a decreased risk of ovarian hyperstimulation syndrome," the authors conclude.

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