A 66-year-old man on stable carbidopa-levodopa therapy for Parkinson's disease reports increasing end-of-dose wearing off. Carbidopa-levodopa combined with a new oral drug improves symptom control. The added drug acts by inhibiting catechol-O-methyltransferase. Which drug matches this mechanism?
- A Entacapone ✓
- B Rasagiline
- C Amantadine
- D Pramipexole
Correct answer: A. Entacapone
Explanation
Entacapone is a peripheral COMT inhibitor that blocks methylation of levodopa to 3-O-methyldopa, prolonging levodopa half-life and increasing its bioavailability, thereby reducing wearing-off when added to carbidopa-levodopa. Rasagiline is a selective MAO-A inhibitor, pramipexole is a direct dopamine agonist, and amantadine acts through glutamate antagonism and dopamine release, so none matches the stated mechanism.
Reference: Katzung's Basic and Clinical Pharmacology, 15th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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