Compounds of the formula I: or a pharmaceutically acceptable salt thereof, wherein, R 1 is optionally substituted triazolyl, and R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 are as defined herein. Also disclosed are methods of using the compounds for treating diseases associated with P2X 3 and/or a P2X 2/3 receptor antagonists and methods of making the compounds.