Histamine H 4 Receptor Ligands: Future Applications and State of Art

Histamine is a chemical transmitter found practically in whole organism and exerts its effects through the interaction with H 1 to H 4 histaminergic receptors. Specifically, H 4 receptors are found mainly in immune cells and blood‐forming tissues, thus are involved in inflammatory and immune processes, as well as some actions in central nervous system. Therefore, H 4 receptor ligands can have applications in the treatment of chronic inflammatory and immune diseases and may be novel therapeutic option in these conditions. Several H 4 receptor ligands have been described from early 2000's until nowadays, being imidazole, indolecarboxamide, 2‐aminopyrimidine, quinazoline, and quinoxaline scaffolds the most explored and discussed in this review. Moreover, several studies of molecular modeling using homology models of H 4 receptor and QSAR data of the ligands are summarized. The increasing and promising therapeutic applications are leading these compounds to clinical trials, which probably will be part of the next generation of blockbuster drugs.