The present invention relates to compounds of formula (I) or the tautomers or pharmacologically acceptable acid addition salts thereof, characterized by a topological polar surface area value (TPSA) of at least 145, wherein R1, R2, R3, R4, X, and Z− have one of the meanings as defined in the specification, to the use of compounds of formula (I) as medicaments, to pharmaceutical compositions comprising at least one compound of formula (I), as well as to medicament combinations containing one or more compounds of formula (I). The compounds are ENaC inhibitors useful for the treatment of respiratory diseases and allergic diseases of the airways.
