A patient came to the casualty with acute bronchial asthma after treatment of glaucoma. The probable drug may be: (A) Timolol, (B) Betaxolol, (C) Latanoprost, (D) Anticholinesterase
Answer is A. Timolol is a non selective β blocker (act on β1& β2 ). β2 blocking effect of Timolol cause blockage of dilator β2 receptor so it can precipitate asthma. Whereas Betaxolol is cardioselective beta blocker that acts only on β2  receptor.