Fexofenadine Related Compound C,4-(4-(hydroxydiphenylmethyl)piperidin-1-yl)-1-(4-isopropylphenyl)butan-1-ol,"Hydrochloride salt of Decarboxy Fexofenadine a photodegradation product of Fexofenadine , the active metabolite of Terfenadine , a H1-histamine receptor antagonist.;Impurity in commercial preparations of Fexofenadine",Fexofenadine Impurity