I-18) were synthesized and characterized by IR, 1H-NMR, 13C-NMR and HRMS spectrum. The potency of these compounds was evaluated in a murine model of niacin-induced flushing. The results indicated that most compounds exhibited faster-acting effect of suppressing vasodilation than laropiprant. Among them, I-1, I-2, I-3, I-9, I-13, I-15 and I-16 exhibited substantial flushing inhibitory effect. Especially, I-1 and I-2 showed higher potency than laropiprant and would be valuable for further investigation. Keywords Anti-allergic agents Laropiprant derivatives Synthesis Flushing Biological evaluation" />