Attention deficit hyperactivity disorder management
There are two major medications derived from methylphenidate's isomers: a racemic mixture of half d-threo-methylphenidate and half l-threo-methylphenidate called methylphenidate (Ritalin, Concerta), and an enantiopure formulation containing just d-threo-methylphenidate called dexmethylphenidate (Focalin).
Ribavirin
Ribavirin's carboxamide group can make the native nucleoside drug resemble adenosine or guanosine, depending on its rotation. For this reason, when ribavirin is incorporated into RNA, as a base analog of either adenine or guanine, it pairs equally well with either uracil or cytosine, inducing mutations in RNA-dependent replication in RNA viruses. Such hypermutation can be lethal to RNA viruses.