Merrion Pharmaceuticals was developing an oral tablet formulation of acyline, a gonadotropin-releasing hormone (GnRH) antagonist, referred to as MER 104. MER-104 effectively suppresses luteinizing hormone (LH) and follicle-stimulating hormone (FSH) secretion in man. Acyline has been investigated for the prevention and treatment of hypogonadism and contraception. Injectable forms have been administered successfully in man in Phase II studies as part of a potential contraceptive regimen. MER-104 is an enteric coated acyline tablet developed by Merrion Pharmaceuticals using GIPET™ I technology to enable the oral administration of this decapeptide. The development of acyline appears to have been discontinued.