Pharma & Specialty Chemical Standards

Fexofenadine, the IUPAC name 4-[[3-[[4-(hydroxydiphenylmethyl)-1-piperidinyl]methyl]-1-piperidinyl]methyl]benzoic acid, is a second-generation H1-antihistamine with molecular formula C32H39NO3 and molecular weight 489.66 g/mol. Structurally, it features a diphenylmethyl group and two piperidine rings, conferring lipophilicity and metabolic stability. Therapeutically, it treats allergic rhinitis and urticaria by selectively blocking peripheral histamine H1 receptors. Its low water solubility (logP ~4.5) and high plasma protein binding (>97%) influence bioavailability. Mechanistically, it competitively inhibits histamine-mediated vasodilation and pruritus without significant central nervous system penetration due to poor blood-brain barrier permeability.