| abstract |
The present invention provides compounds of formula (I) wherein R 1, R 2, R 3 and R 4 have any of the values defined in the specification, and their pharmaceutically acceptable salts, which are useful as agents in the treatment of diseases. and cftr-mediated and modulated conditions including cystic fibrosis, sjögren's syndrome, pancreatic insufficiency, chronic obstructive pulmonary disease, and chronic obstructive airway disease. Pharmaceutical compositions comprising one or more compounds of formula (also provided) i). |