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).
Modafinil
In any case, there is nonetheless a good deal of evidence to indicate that modafinil is producing at least a portion of its wakefulness-promoting effects by acting as a DRI, or at least via activation of the dopaminergic system. In support of modafinil acting as a dopaminergic agent, its wakefulness-promoting effects are abolished in DAT knockout mice (although it is important to note that DAT knockout mice show D and D receptor and norepinephrine compensatory abnormalities, which might confound this finding), reduced by both D and D receptor antagonists (although conflicting reports exist), and completely blocked by simultaneous inactivation of both D and D receptors. In accordance, modafinil shows full stimulus generalization to other DAT inhibitors including cocaine, methylphenidate, and vanoxerine, and discrimination is blocked by administration of both ecopipam (SCH-39166), a D receptor antagonist, and haloperidol, a D receptor antagonist. Partial substitution was seen with the DRA dextroamphetamine and the D receptor agonist PNU-91356A, as well as with nicotine (which indirectly elevates dopamine levels through activation of nicotinic acetylcholine receptors).