Experts recommend reducing or stopping PD medications in the following order: anticholinergic agents, amantadine, dopamine agonists, monoamine oxidase inhibitors, catechol-O-methyltransferase inhibitors, and lastly, levodopa.185 If this strategy is ineffective, second-generation antipsychotics (never first-generation) can be used cautiously. This evidence concerns the gene COMT and Parkinson disease.