Compounds of the formula I:or a pharmaceutically acceptable salt thereof, wherein, R1 is optionally substituted phenyl or optionally substituted pyridinyl, and R2, R3, R4, R5, R6, R7, R8 and R9 are as defined herein. Also disclosed are methods of using the compounds for treating diseases associated with P2X3 and/or a P2X2/3 receptor antagonists and methods of making the compounds.
