Mechanism of aspirin action is
Aspirin inhibits the synthesis of thromboxane A2 by irreversible acetylation of the enzyme cyclooxygenase.Other salicylates and nonsteroidal anti-inflammatory drugs also inhibit cyclooxygenase but have a shoer duration of inhibitory action because they cannot acetylate cyclooxygenase; that is, their action is reversible.Katzung 13e pg: 595