which are responsible for the symptom that NSAIDs are commonly used to treat. However, prostaglandin H2 is also metabolized into prostacyclin and thromboxane A2, 2 potent vasoactive prostanoids with directly opposing effects. Prostacyclin, primarily produced by endothelial cells, is a vasodilator and inhibits platelet aggregation, while thromboxane-A2, produced primarily by platelets, is a vasoconstrictor and promotes platelet aggregation.