Abstract: Compounds of formula 1 are modulators of P2X3 useful for the treatment of pain and genitourinary, gastrointestinal, and respiratory disorders: wherein R1 is —C(?S)CH3, pyridyl, pyrimidinyl, pyrazinyl, thiazolyl, furyl, furylcarbonyl, acetyl, or carbamoyl; R2a and R2b are independently H, methyl, or ethyl; R3 is H or methyl; Y is a bond, —(CR4R5)n— or —CR4?CR5—; wherein R4 and R5 are each independently H or methyl and n is 1 or 2; X is N or CH; A is phenyl, 5-membered heterocyclyl, or 6-membered heterocyclyl; R6, R7 and R8 are each independently H, halo, lower alkyl, cycloalkyl, alkylthio, alkylthio-lower alkyl, alkylsulfonyl-lower alkyl, di(lower alkyl)amino-lower alkyl, morpholinyl-lower alkyl, 4-methyl-piperazinyl-methyl, trifluoromethyl, pyridyl, tetrazolyl, thiophenyl, phenyl, biphenyl, or benzyl (where thiophenyl, phenyl and benzyl are substituted with 0-3 lower alkyl, halo, sulfonamido, trifluoromethyl, lower alkoxy or lower alkylthio) or R6 and R7 together form a 5-membered or 6-membered carbocycl