Review Question - QID 108845

A 61-year-old female with a history of breast cancer currently on chemotherapy is brought by her husband to her oncologist for evaluation of a tremor. She reports that she developed a hand tremor approximately six months ago, prior to the start of her chemotherapy. The tremor is worse at rest and decreases with purposeful movement. She has experienced significant nausea and diarrhea since the start of her chemotherapy. Her past medical history is also notable for diabetes and hypertension treated with metformin and lisinopril, respectively. She takes no other medications. On examination, there is a tremor in the patient’s left hand. Muscle tone is increased in the upper extremities. Gait examination reveals difficulty initiating gait and shortened steps. Which of the following medications is contraindicated in the management of this patient’s nausea and diarrhea?