The longest acting antihistaminic is: (A) Terfenadine, (B) Astemizole, (C) Fexofenadine, (D) Cetrizine
Answer is A. Terfenadine is a prodrug broken down to fexofenadine.so long duration of action followed by astemizole Ref: Goodman Gillman 12th ed.Pg 924.