Comparing the clinical utility of GnRH antagonist to GnRH agonist in an oocyte donation program

A potent gonadotropin-releasing hormone (GnRH) antagonist (Nal-Glu) was administered to downregulate the pituitaries of oocyte donors (n = 15) and block their midcycle luteinizing hormone surges. Donors received Nal-Glu at a dose of 50 microg/kg/day i.m., beginning when lead follicles reached a mean diameter of 14 mm. All donors had previously undergone controlled ovarian hyperstimulation cycles using GnRH agonist (leuprolide acetate) administered subcutaneously beginning during the midluteal phase. Ovarian stimulation was performed using human menopausal gonadotropin (hMG). Compared to previous stimulated cycles using agonist and hMG, cycles with antagonist and hMG demonstrated a significant decrease in the amount of hMG required for follicle stimulation (24.7 +/- 1.8 vs. 31.3 +/- 2.5 ampules; p < 0.05). There was also a significant reduction in the number of patient visits necessary per cycle (5.1 +/- 1.4 vs. 9.3 +/- 1.1; p < 0.05) and the required duration of treatment to accomplish a cycle (27.1 +/- 5.3 vs. 11.3 +/- 1.3 days; p < 0.05). However, there were no differences noted in the number of oocytes retrieved (10.7 +/- 4.5 vs. 13.0 +/- 6.3), the fertilization rate of oocytes (60.3 +/- 10.2 vs. 53.9 +/- 11.6%), or the number of embryos obtained per recipient (5.5 +/- 3.2 vs. 7.6 +/- 5.3). Clinical pregnancies occurred in 7 of 15 transfer cycles to recipients. There were no serious adverse side effects experienced by donors using antagonist. We conclude that the use of GnRH antagonist significantly reduces the amount of medication and the time required for ovarian hyperstimulation and that is a useful adjunct in cycling oocyte donors.