A highly modified luteinizing hormone-releasing hormone (LHRH) decapeptide with a terminal amide group, this peptide is a LHRH antagonist. It regulates the expression of Galphas and Galphai protein subunits and adenylate cyclase activity in ovary, breast and pituitary. Cetrorelix competitively inhibits LHRH receptor in the pituitary gland to suppress ovarian and testicular functions.