Abstract: The present invention provides a method of enhancing the absorption of molecules across the airway epithelium, thereby enhancing the delivery of desired therapeutic or diagnostic agents across the airway epithelium via the systemic circulation to the target site of action. The method comprises administration of a formulation comprising a pharmaceutical composition comprising a synthetic or natural nucleoside diphosphate, nucleoside triphosphate, or dinucleoside polyphosphate, together with a pharmaceutically acceptable carrier. Preferably the nucleotide is a P2Y receptor agonist which is administered at any time during treatment with a therapeutic or diagnostic agent. A preferred embodiment is a method of administering a pharmaceutical composition comprising a P2Y receptor agonist with enhanced resistance to extracellular hydrolysis, such as dinucleoside polyphosphate compounds.