M4 mAChR Modulator-1

M4 mAChR Modulator-1 (compound 23i) acts as a positive allosteric modulator (PAM) of the M4 mAChR. It demonstrates a stronger synergistic effect in β-arrestin recruitment compared to G protein activation when interacting with ACh. Additionally, while its PAM effects are weaker in G protein-mediated responses, they are more potent in β-arrestin recruitment.