GnRH antagonists

Ovarian stimulation is an important step in the success rate of in vitro fertilization (IVF) allowing multiple follicular growth, several oocytes and consequently more embryos. The combination of GnRH-antagonists (GnRH-ant) and gonadotrophins is now available for clinical use and represent a valid alternative to classical protocol with GnRH agonist. GnRH-antagonists induce a direct block of GnRH receptor with a rapid decrease in LH and FSH, preventing LH surge. Two protocols has been designed for assisted reproduction technology (ART) treatment: multiple-dose protocol and a single-dose. Both protocols are simply, efficacious, started in the late follicular phase and do not have side effects. A review of GnRH-antagonist applications in ART cycles are presented. Smaller doses of gonadotrophins, shorter stimulation period and lower ovarian hyperstimulation syndrome (OHSS) incidence are reported in literature using GnRH-antagonist compared to agonist. Triggering of ovulation, the use in polycystic ovarian syndrome (PCOS) and poor reponders patients are other interesting indication. Regarding to pregnancy rate and potentially adverse effects of drugs on endometrium or implantation needed more data.