This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
Which of the following vitamin should not be supplemented in a patient of parkinsonism on levodopa therapy 
Select and explain. 
A. Thiamine, B. Pyridoxine, C. Cobalamine, D. Pantothenic acid
B: Pyridoxine
Answer: B: Pyridoxine 
Explanation: Pyridoxine acts as cofactor for Dapa decarboxylase enzyme that converts levodopa to dopamine. 
As peripheral conversion can cause postural hypotension, nausea & vomitting and also makes the therapy ineffective. Pyridoxine should not be supplemented.