This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
All of the following antihistaminics can be used topically except: 
Select and explain. 
A. Ketotifen, B. Levocetrizine, C. Olapatadine, D. Astemizole
B: Levocetrizine
Answer: B: Levocetrizine 
Explanation: Azelastine, Astemizole, Ketotifen, Olapatadine are the antihistaminics that can be used topically in allergic rhinitis and conjuctivitis.