- If the subject is receiving levodopa/carbidopa, levodopa/benserazide, a dopamine agonist, catechol-o-methyltransferase (COMT) inhibitor, or other Parkinson's medication,with teh exception of Azilect(rasagiline), the dose must have been stable for at least 60 days prior to the screening visit (Visit 1) and must remain stable for the duration of the study. No such medication can be initiated during the study. Subjects receiving rasagiline or CoQ10 must be on a stable dose for at least 90 days prior to the screening visit.