The present invention provides a compound of a formula (I): or a pharmaceutically acceptable salt thereof; a process for preparing such a compound; and to the use of such a compound in the treatment of an ENaC mediated disease state (such as asthma, CF or COPD).本發明提供一種式(I)的化合物:或其之藥學上可接受的鹽;一種製備此一化合物的方法;以及此一化合物於治療ENaC媒介的疾病狀態之用途(例如氣喘、CF或COPD)。