Acyline (developmental code name MER-104) is a gonadotropin-releasing hormone analogue (GnRH analogue) and gonadotropin-releasing hormone antagonist (GnRH antagonist) which was never marketed.

[1][2][3] It has been shown to suppress gonadotropin and testosterone levels in men.

[1][2][3] Acyline is a peptide and under normal circumstances is not orally active.

[3] For this reason, it has instead been administered by subcutaneous injection.

This drug article relating to the genito-urinary system is a stub.