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 agents enhances the bioavailability of levodopa - 
Select and explain. 
A. Amantadine, B. Ropinirole, C. Entacapone, D. Selegiline
C: Entacapone
Answer: C: Entacapone 
Explanation: Ans. is 'c' i.e., Entacapone o When peripheral decarboxylation of levodopa is blocked by carbidopa/benserazide, it is mainly metabolized by COMT to 3-0-methyldopa. o Blockade of this pathway by entacaptone/tolcapone fuher prolongs the t 1/2 of levodopa and allows a larger fraction of administered dose to cross to brain.