Abstract: This invention is directed to a method of enhancing or facilitating the clearance of the lung mucus secretions in a subject. This invention is also directed to a method of facilitating the hydration of the lung mucus secretions in a subject. This invention is further directed to a method of preventing or treating diseases or conditions associated with impaired lung or airway function in a human or other mammal. The method comprises administering to a subject a pharmaceutical composition comprising a therapeutic effective amount of P2Y6 receptor agonist compound, wherein said amount is effective to activate the P2Y6 receptors on the luminal surface of lung epithelia. The P2Y6 receptor agonist compounds useful for this invention include mononucleoside 5?-diphosphates, dinucleoside monophosphate, dinucleoside diphosphates, or dinucleoside triphosphates of general Formula I, or salts, solvates, hydrates thereof.