Fexofenadine is a second-generation selective histamine H
1 receptor antagonist that does not cross the blood brain barrier. Fexofenadine competitively binds peripheral H
1-receptors, thereby stabilizing an inactive conformation of the receptor. Consequently, usual allergic responses as a result of mast-cell degranulation followed by the release of multiple inflammatory mediators, such as interleukins, prostaglandins, and leukotriene precursors, are blocked. Grapefruit and other fruit juices have recently been shown to be potent inhibitors of a number of organic anion-transporting polypeptides (OATPs) in the gastrointestinal tract. Thus, these juices decrease the absorption of fexofenadine by inhibiting the activity of OATPs. For your reference, fexofenadine is the active metabolite of terfenadine [
T3977]. (The product is for research purpose only.)