Ambroxol: A metabolite of BROMHEXINE that stimulates mucociliary action and clears the air passages in the respiratory tract. It is usually administered as the hydrochloride.Expectorants: Agents that increase mucous excretion. Mucolytic agents, that is drugs that liquefy mucous secretions, are also included here.Bromhexine: A mucolytic agent used in the treatment of respiratory disorders associated with viscid or excessive mucus. (From Martindale, The Extra Pharmacopoeia, 30th ed, p744)Guaifenesin: An expectorant that also has some muscle relaxing action. It is used in many cough preparations.