Fexofenadine, the carboxylic acid metabolite of terfenadine, is widely available. It
accounts for the antihistaminic properties of terfenadine, which is very rapidly metabolized via
CYP3A4-catalyzed processes. Members of the organic anion transporter protein family and
the drug efflux transporter P-glycoprotein are involved in the disposition of fexofenadine.
Fexofenadine does not have the antiarrhythmic side effects of terfenadine.