The serotonin 5-HT4 receptor: Part 3: Design and pharmacological evaluation of a new class of antagonists

The design, synthesis and pharmacological activity of a new class of potent and selective 5-HT4 receptor antagonists containing an indole nucleus linked to a carbazimidamide are presented. 4c, a representative member of our new class is a potent competitive antagonist at 5-HT4 receptors with a pA2 value of 8.4, displaying selectivity (ranging from 20 to over 1000 fold) versus other serotonin receptor subtypes.