.png){kind=icon}
Proteins and enzymes
- Aspirin inhibits both COX-1 and COX-2 enzymes but only COX-1 leads to formation of thromboxane A2 in blood platelets and this causes platelet aggregation. Inhibition of COX-1, therefore, prevents undesirable thrombotic events. This why low dose aspirin is recommended after coronary bypass surgery.
- COX-2 is responsible for producing prostaglandins which mediate inlflammation. The anti-clotting (low dose) aspirin inhibits COX-1 and the anti-inflammatory (normal) dose aspirin inhibits both COX-1 and COX-2. Aspirin is a more potent inhibitor of COX-1 than COX-2 (~150x) and, therefore a lower dose is required to inhibit COX-1 alone.
- COX-2 catalyses the production of prostaglandins which are cytoprotective to the gastric mucosa. Prolonged inhibition of COX-2 by daily normal dose aspirin may, therefore, lead to gastrotoxicity