Comparison of intermittent and continuous use of a gonadotropin-releasing hormone antagonist (Nal-Glu) in in vitro fertilization cycles: a preliminary report.

The agonistic effect of the gonadotropin-releasing hormone agonist often necessitates an extended period of treatment, resulting in a longer treatment cycle and increased cost. We have evaluated the intermittent use of a gonadotropin-releasing hormone antagonist, Nal-Glu, and have designed a new, simplified protocol for its use in in vitro fertilization. Seven women who had previously undergone treatment with leuprolide acetate and human menopausal gonadotropins were treated with Nal-Glu. Leuprolide acetate, 1 mg/day subcutaneously, was administered in the midluteal phase until down regulation was achieved (estradiol less than 30 pg/ml). Human menopausal gonadotropins, three to four ampules per day intramuscularly, was administered in conjunction with 500 micrograms subcutaneous leuprolide acetate. In the treatment cycles Nal-Glu (50 micrograms/kg/day) was administered intramuscularly on cycle day 1 or 2 for 3 days to achieve down regulation. Human menopausal gonadotropins, three to four ampules intramuscularly, was then administered daily without the antagonist. Nal-Glu was resumed when the follicles reached 14 to 16 mm and was continued until the day of human chorionic gonadotropin administration. Compared with leuprolide acetate-human menopausal gonadotropins cycles, the days required for down-regulation with Nal-Glu were significantly shortened (20.6 +/- 4.1 vs 1.6 +/- 0.3 days, p less than 0.001), as was total cycle length (31.3 +/- 5.8 vs 11.0 +/- 1.0 days, p less than 0.01). The mean number of days of treatment with human menopausal gonadotropins, the mean number of ampules of human menopausal gonadotropins, peak estradiol levels, the number of oocytes, and the percent of oocytes fertilized were not statistically different. No luteinizing hormone surges were detected with Nal-Glu in serum or urine. Nal-Glu was well tolerated, and five pregnancies have resulted. We conclude that intermittent administration of Nal-Glu is highly effective in achieving down-regulation and blocking spontaneous luteinizing hormone surges. Compared with leuprolide acetate-human menopausal gonadotropins cycles, an equally high oocyte and embryo yield may be anticipated. This new protocol substantially decreases cycle length and increases patient convenience.