2-Butenoic acid, 4-(((5alpha,6beta)-17-(cyclopropylmethyl)-4,5-epoxy-3,14-dihydroxymorphinan-6-yl)amino)-4-oxo-, methyl ester, (E)- 72782-05-9 Naltrexone fumarate methyl ester beta-Fna beta-Funaltrexamine