Methods are provided for modulating MRGPR X4 generally, or for treating a MRGPR X4 dependent condition more specifically, by contacting the MRGPR X4 or administering to a subject in need thereof, respectively, an effective amount of a compound having the structure of Formula (I):




or a pharmaceutically acceptable isomer, racemate, hydrate, solvate, isotope, or salt thereof, wherein n, x, A, Q1, Q2, Z, R, R1, R2, R3, R4 and R5 are as defined herein. Pharmaceutical compositions containing such compounds, as well as to compounds themselves, are also provided.