Review Question - QID 212594

A 62-year-old man is referred to neurology by his primary care physician. He is accompanied by his wife. The patient reports having a resting tremor in his left hand for over a year and some “stiffness” in his left arm. His wife notes that he has started to walk "funny" as well. He has a history of hypertension and hyperlipidemia. He takes aspirin, amlodipine, and rosuvastatin. On physical examination, you notice a repetitive circular movement of his left index finger and thumb that resolves with active movement of the hand. Passive motion of the left upper extremity is partially limited by rigidity. Gait is slow and shuffling. The patient is prescribed the most effective treatment for his disorder. Which of the following is the mechanism of a second drug given to prevent adverse effects of this therapy?