The PLATO trial demonstrated superiority of ticagrelor over clopidogrel in ACS management. Which pharmacokinetic property of ticagrelor makes it distinct from clopidogrel?
- A Ticagrelor is a prodrug requiring CYP2C19 activation
- B Ticagrelor irreversibly blocks P2Y12 receptors
- C Ticagrelor is a direct-acting reversible P2Y12 antagonist requiring no hepatic conversion ✓
- D Ticagrelor acts via P2Y1 receptor blockade
Correct answer: C. Ticagrelor is a direct-acting reversible P2Y12 antagonist requiring no hepatic conversion
Explanation
Ticagrelor is a direct-acting, reversibly binding P2Y12 receptor antagonist that does not require hepatic bioactivation, unlike clopidogrel and prasugrel (which are prodrugs requiring CYP2C19 conversion). This means ticagrelor's action is not subject to the variability of CYP2C19 polymorphisms (loss-of-function variants in 25–30% of Asians) that cause clopidogrel resistance. The PLATO trial showed ticagrelor reduced MACE vs. clopidogrel in ACS with a similar risk of major bleeding but higher rates of dyspnea (adenosine-related side effect).
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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