Ketanserin is a quinazoline derivative and serotonin (5-hydroxytryptamine, 5HT) receptor subtype 2 (5-HTR2) antagonist with potential antihypertensive and antiplatelet activities. Following administration, ketanserin binds to and inhibits the signaling mediated by 5-HTR2, which inhibits serotonin-dependent vasoconstriction and platelet activation.