Comparison of the efficacy of the aromatase inhibitor letrozole and clomiphen citrate gonadotropins in controlled ovarian hyperstimulation: A prospective, simply randomized, clinical trial

Abstract

Objective: To study the efficacy of the aromatase inhibitor letrozole in controlled ovarian hyperstimulation (COH). Material and methods: In this prospective simply randomized clinical trial, one hundred forty patients with unexplained infertility undergoing intrauterine insemination (IUI) therapy were randomized to receive either letrozole or clomiphene citrate (CC)-gonadotropin. The patients were selected among patients referred to one university hospital and one private infertility clinic. A letrozole dose of 5 mg/day (n=70) was given on days 3-7 of the menstrual cycles. Clomiphen citrate a dose of 100 mg/day was given like letrozole but combined with human menopausal gonadotropin (hMG) dose of 75 IU/ml administered every day starting on day 6. Ovulation was triggered with urinary hCG (10,000 IU) when the leading follicle(s) reached 18 mm in diameter. A single IUI was performed 36 hours later. The luteal phase was supplemented with micronized progesterone vaginally. Ovarian stimulation response (E2 levels and number of follicles) was primary outcome. Results: There were no differences in demographic characteristics between groups. The number of mature follicles (1.8±0.7 vs. 2.46±2.3; P=0.042) and serum E2 level on the day of hCG (310±135.4 vs. 1,670.7±1021.8 pg/ml, respectively; P<0.0001) were significantly lower in letrozole group. A significantly higher endometrial thickness was observed at the time of hCG administration in patients that received letrozole (9.7±1.6 mm vs. 7.8±2 mm; P<0.001).Clinical pregnancy rates also were significantly higher in letrozole group (32.8% vs. 14.3%, respectively; P<0.01). Conclusion: The aromatase inhibitor letrozole appears to constitute a good alternative to CC-gonadotropin in patients with unexplained infertility undergoing COH cycles combined with IUI therapy. © 2008 Springer Science+Business Media, LLC.