Synonyms: methylnaltrexone;17-(Cyclopropylmethyl)-4,5α-epoxy-3-methoxy-14-hydroxymorphinan-6-one;3-Methoxy-14-hydroxy-17-(cyclopropylmethyl)-4,5α-epoxymorphinan-6-one;3-O-Methylnaltrexone;4,5α-Epoxy-3-methoxy-14β-hydroxy-17-(cyclopropylmethyl)morphinan-6-one;Naltrexone methyl ether;17-(Cyclopropylmethyl)-4,5alpha-epoxy-3,14-dihydroxy-17-methyl-6-oxomorphinanium;17-(Cyclopropylmethyl)-4,5-epoxy-3,14-dihydroxymorphinanium-6-one