This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Other topics and Adverse effects, Subject name: Anatomy
[{'content': 'Entacapone may be useful in patients being treated with levodopacarbidopa combination because it: \nSelect and explain. \nA. Activates COMT, B. Decreases formation of 3-OMD, C. Inhibits monoamine oxidase type B, D. Inhibits dopamine uptake', 'role': 'user'}, {'content': 'Answer: B \nExplanation: (Ref: KDT 6/e p421) Levo-dopa is conveed to dopamine by dopa decarboxylase (that cannot cross blood brain barrier). Carbidopa is an inhibitor of dopa decarboxylase in the periphery. It therefore increases the amount of 1-dopa that reaches the brain (due to inhibition of peripheral metabolism to dopamine). Due to inhibition of 1-dopa metabolism (by dopa decarboxylase), an alternative pathway of metabolism by catechol-o-methyl transferase (COMT) is activated.COMT metabolizes 1-dopa to 3-o-methyl dopa (3-OMD) that can complete with 1-dopa for entry in the brain. Entacapone and tolcapone is useful in Parkinsonism by inhibiting COMT.', 'role': 'assistant'}]