Ganirelix acetate is a synthetic decapeptide with high antagonistic activity against naturally occurring gonadotropin-releasing hormone (GnRH). Ganirelix works by blocking the action of GnRH upon the pituitary, thus rapidly suppressing the production and action of LH and FSH. It is derived from native GnRH with substitutions of amino acids at positions 1, 2, 3, 6, 8, and 10 to form the following molecular formula of the peptide: N-acetyl-3-(2-napthyl)-D-alanyl-4-chloro-D-phenylalanyl-3-(3-pyridyl)-D-alanyl-L-seryl-L-tyrosyl-N 9 ,N 10 -diethyl- D-homoarginyl-L-leucyl-N 9 ,N 10 -diethyl-L-homoarginyl-L-prolyl-D-alanylamide acetate.