<unk>  is the immediate precursor to dopamine.<unk>  is a selective, reversible catechol-O-methyltransferase (COMT) inhibitor that prevents the degradation of<unk> .<unk>  does not cross the blood–brain barrier.<unk>  is a peripheral aromatic L-amino acid decarboxylase (AADC) inhibitor.<unk> , which also does not cross the blood–brain barrier, is combined with<unk>  to prevent its conversion to dopamine in the periphery.
Carbidopa/levodopa/entacapone
Fluorodopa
Bromperidol decanoate
Donepezil
3-Quinuclidinyl benzilate
Protriptyline
Perhexiline
Rivastigmine