17-(Cyclopropylmethyl)-4,5-epoxy-3,14-dihydroxymorphinanium-6-one 17-(Cyclopropylmethyl)-4,5alpha-epoxy-3,14-dihydroxy-17-methyl-6-oxomorphinanium 83387-25-1 Methylnaltrexone Methylnaltrexonium Morphinanium, 17-(cyclopropylmethyl)-4,5-epoxy-3,14-dihydroxy-17-methyl-6-oxo-, (5alpha)- Mrz-2663 N-Methylnaltrexone Naltrexone MB Quaternary ammonium naltrexone