Pharmacology · single question
What is the EFFECT of Clopidogrel and Aspirin on hemostasis?
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Correct answer: B. Impair platelet FUNCTION
Impair platelet function (B). Both aspirin and clopidogrel are antiplatelet drugs that affect platelet function rather than number:
• Aspirin: irreversibly inhibits cyclooxygenase (COX-1 and COX-2) → prevents thromboxane A2 synthesis → impairs platelet aggregation. Effect lasts ~7-10 days (platelet lifespan).
• Clopidogrel (Plavix): irreversibly blocks ADP (P2Y12) receptors on platelets → prevents ADP-mediated platelet aggregation. Also ~7-10 day effect.
• Important: These drugs do NOT affect the platelet COUNT (CBC normal) and do NOT affect PT/INR (coagulation cascade normal).
• Dental significance: Patients on antiplatelet therapy have prolonged bleeding time. Generally, single antiplatelet (aspirin alone) does NOT require discontinuation for routine dental procedures — local hemostatic measures suffice.
• Aspirin: irreversibly inhibits cyclooxygenase (COX-1 and COX-2) → prevents thromboxane A2 synthesis → impairs platelet aggregation. Effect lasts ~7-10 days (platelet lifespan).
• Clopidogrel (Plavix): irreversibly blocks ADP (P2Y12) receptors on platelets → prevents ADP-mediated platelet aggregation. Also ~7-10 day effect.
• Important: These drugs do NOT affect the platelet COUNT (CBC normal) and do NOT affect PT/INR (coagulation cascade normal).
• Dental significance: Patients on antiplatelet therapy have prolonged bleeding time. Generally, single antiplatelet (aspirin alone) does NOT require discontinuation for routine dental procedures — local hemostatic measures suffice.