Discovery of highly potent, lung-localized epithelial sodium channel inhibitors.

The design, synthesis and biological evaluation of novel dimeric pyrazinoylguanidines for the treatment of cystic fibrosis (CF) are reported herein. When administered directly to the lung in a guinea pig tracheal potential difference (TPD) model, the dimeric compounds were found to have superior potency, longer duration of action in the lung, and significantly reduced extra-pulmonary exposure in comparison to the corresponding monomeric ENaC blockers, which have been evaluated in the clinic but shown to have dose-limiting kidney toxicity.