Ticagrelor differs from clopidogrel in that it does not require hepatic bioactivation. Ticagrelor's mechanism and pharmacokinetic advantage is:
- A Ticagrelor irreversibly blocks P2Y12 receptors and is itself the active drug without CYP2C19 conversion
- B Ticagrelor is a P2Y1 receptor antagonist with a direct thrombin inhibitory component
- C Ticagrelor is a reversible P2Y12 receptor antagonist and is itself the active drug; it has faster onset and offset, and efficacy independent of CYP2C19 genotype ✓
- D Ticagrelor requires CYP3A4 activation and is contraindicated with strong CYP3A4 inhibitors
Correct answer: C. Ticagrelor is a reversible P2Y12 receptor antagonist and is itself the active drug; it has faster onset and offset, and efficacy independent of CYP2C19 genotype
Explanation
Ticagrelor is an active drug (not a prodrug) that reversibly and non-competitively inhibits the P2Y12 ADP receptor; it does not require CYP2C19 bioactivation, eliminating loss-of-function CYP2C19 polymorphism as a source of treatment failure seen with clopidogrel. Its reversible binding allows faster offset of platelet inhibition (12–24 hours) compared to clopidogrel/prasugrel which irreversibly inhibit P2Y12 (reversal requires new platelet synthesis over 5–7 days). Ticagrelor is metabolized by CYP3A4 but is itself active.
Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.
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