<prompt> Mechanism of action of timolol is ?Nonselective beta blockerNonselective alpha blockerSelective beta 1 blockerSelective beta 2 blocker  <response>: Ans. is a i.e., Nonselective beta blocker Timolol is a non selective beta blocker betal beta 2. Thus when it is used in the treatment of glaucoma it can precipitate an attack of asthma by blocking beta 2 receptors. 