The present invention relates to the compound of the formula: or pharmaceutically acceptable salts thereof, as well as compositions containing the same, processes for the preparation of the same, and therapeutic methods of use therefore in promoting hydration of mucosal surfaces and the treatment of diseases including chronic obstructive pulmonary disease (COPD), asthma, bronchiectasis, acute and chronic bronchitis, cystic fibrosis, emphysema, and pneumonia.