A structurally biased chemical library of pyridazinylpiperazine analogs was prepared in an effort to improve the pharmaceutical and pharmacological profile of the lead compound N-(4- tertiarybutylphenyl)-4-(3-chloropyridin-2-yl) tetrahydropyrazine-1 (2H)-carboxamide (BCTC). The library was evaluated for VR1 antagonist activity in capsaicin-induced (CAP) and pH5. 5- induced (pH) FLIPR assays in a human VR1-expressing HEK293 cell line. The most ...