4-(2-Pyridyl)piperazine-1-benzimidazoles as potent TRPV1 antagonists.

A series of 4-(2-pyridyl)piperazine-1-benzimidazole analogues based on compound 1 was synthesized and evaluated for TRPV1 antagonist activity in capsaicin-induced (CAP) and pH5.5-induced (pH) FLIPR assays in a human TRPV1-expressing HEK293 cell line. Potent TRPV1 antagonists were identified through SAR studies. From these studies, several antagonists were found, with IC(50) values ranging from 32 nM to approximately 5000 nM. Among these, 11 [IC(50)=90 nM (CAP) and 104 nM (pH)] was further evaluated and found to be orally available in rats (F%=19.7).