H4 Receptor Antagonist Compounds with Low hERG Inhibition

The patent applies parameter changes by systematically modifying molecular parameters of the H4 receptor antagonist compounds. Specific changes include adjusting the R1-R6 substituent groups in the core molecular structure to optimize binding affinity to low nM concentrations while maintaining selectivity against H1-H3 receptors. The patent identifies specific substituent patterns that achieve both high affinity and selectivity simultaneously.

The patent applies local quality by introducing specific functional groups and substituent patterns at particular positions (R1-R6) in the molecular structure. Each position is optimized with specific chemical groups that contribute to H4 receptor binding while avoiding binding to H1-H3 receptors. The local chemical environment at each position is carefully designed to achieve selective interaction with the H4 receptor.

The patent applies the taking out principle by removing or eliminating the problematic hERG inhibitory activity from the compound class while maintaining H4 receptor antagonism. The patent identifies and excludes structural features that cause hERG inhibition, focusing instead on substituent patterns that provide anti-inflammatory activity without cardiac side effects. The safe compounds are extracted from the broader class of H4 antagonists.

The patent applies blessing in disguise by converting potential harmful effects into beneficial outcomes. The patent identifies structural features that could potentially cause issues and instead designs compounds where these same structural elements provide selective H4 binding and anti-inflammatory activity while being inherently safe regarding hERG channels. The potential harm is transformed into a benefit through careful structural design.