GNRH1 and Infertility: The decapeptide Cetrorelix ([Ac-D-Nal -(p-Cl)-D-Phe -D-Pal -Ser - Thy -D-Cit -Leu -Arg -Pro -D-Ala –NH2 ], Figure 1), is a third-generation Gn-RH antagonist that is currently mainly used in infertility treatment (for the prevention of premature ovulation in patients undergoing controlled ovarian stimulation) and is suitable for the treatment of benign prostatic hypertrophy and sexual hormone-dependent tumors (1, 2, 3, 4 and 5).