Antiplatelet drug acting via purinergic receptors, not largely impacted by CYP2C19 polymorphism is:
**Core Concept**
The question is testing the student's knowledge of antiplatelet drugs that act via purinergic receptors, specifically those that are not significantly affected by CYP2C19 polymorphism. Purinergic receptors are a class of G protein-coupled receptors that respond to adenosine diphosphate (ADP), a key player in platelet aggregation.
**Why the Correct Answer is Right**
One of the primary mechanisms by which antiplatelet drugs inhibit platelet aggregation is through the blockade of ADP receptors on platelet surfaces. The correct answer is a drug that acts through this mechanism without being significantly impacted by CYP2C19 polymorphism. CYP2C19 is an enzyme responsible for the metabolism of several antiplatelet drugs, including clopidogrel. Variations in this enzyme can significantly affect the efficacy of these drugs.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because most antiplatelet drugs that act via purinergic receptors are affected by CYP2C19 polymorphism, particularly those that require metabolic activation, such as clopidogrel.
**Option B:** This option is incorrect because while prasugrel is a potent antiplatelet drug, it is not primarily known for its action through purinergic receptors and is significantly affected by CYP2C19 polymorphism.
**Option C:** This option is incorrect because ticagrelor is an antiplatelet drug that acts through a different mechanism, specifically the inhibition of the adenosine diphosphate (ADP) receptor P2Y12, but it is significantly affected by CYP2C19 polymorphism.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that the efficacy of certain antiplatelet drugs can be significantly impacted by CYP2C19 polymorphism, which can lead to reduced response in patients with certain genotypes. This highlights the importance of genetic testing in patients with high-risk cardiovascular disease.
**Correct Answer:** C. Tirofiban is a non-peptide antagonist of the glycoprotein IIb/IIIa receptor that acts via a non-purinergic receptor.