Is Gavilyte N and Trilyte both the generic of nulytely? If a doctor writes for nulytely would giving gavilyte N or trilyte be okay? It kind of confuses me that they seem like a brand by the name so with the generic substitution. Also, in this case is Gavilyte N and Trilyte interchangeable or MD would need to be notified if you change between them. Anyone in retail help me out? Thanks.