Page 171 - pharma 1 theoretical updated MNU_Neat

Clinical pharmacy 2024/2025 Level 3 Pharm D Pharmacology 1 (PO 502)

1- COX-1 Inhibitors

Aspirin

 Mechanism of antiplatelet effect of aspirin:

 Arachidonic acid produced thromboxane A2 and prostacyclin via cyclooxygenase

isozymes.
 Thromboxane A2 (platelet aggregating agent), while prostacyclin has antiplatelet
effect.
 The aspirin-induced suppression of thromboxane A2 synthesis and the resulting

suppression of platelet aggregation last for the life of the platelets “approximately
7 to 10 days”

 Inhibition of thromboxane A2 by small dose (75mg) of aspirin irreversibly
inactivates platelet COX-1 through acetylation of serine residues→ antiplatelet
effect.

 Notes

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