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
Beta 2 agonist used in rescue therapy in acute respiratory conditions are all except? 
Select and explain. 
A. Formoterol, B. Salbutamol, C. Bambuterol, D. Ketotifen
D: Ketotifen
Answer: D: Ketotifen 
Explanation: Ans. is 'd' i.e., Ketotifen Formoterol, Salbutomol and bambuterol are p 2 agonists. o Ketotifen is a mast cell stabilizer.