COMT and Parkinson disease: There are several types of medications available to treat symptoms of PD: levodopa, dopamine agonists (apomorphine hydrochloride, pergolide, pramipexole dihydrochloride, ropinirole hydrochloride, and rotigotine), inhibitors of enzymes that inactivate dopamine (monoamine oxidase type B [MAO-B] inhibitors and catechol-O-methyl transferase [COMT] inhibitors), anticholinergic drugs, and amantadine.