- To ensure performance on cognitive measures are not affected by specific concomitant medications, participants taking methylphenidate, amphetamine/dextroamphetamine, atomoxetine, an acetyl cholinesterase inhibitor, an atypical antipsychotic, kava kava, Ginkgo Biloba, or an anxiolytic drug may be excluded unless their dose and dosing frequency have remained stable for 30 days prior to receiving study drug. Continued participation also requires the dose and dosing frequency remain stable throughout the study.