HETEROCYCLIC COMPOUNDS AND THEIR USE AS HISTAMINE H4 LIGANDS.

摘要

A compound of formula (I) wherein: wherein X4 is NR1 or S; _ X1 is CR3; X2 i s NRe or O, provided that X2 is NRe where X1 is N; X3 is N; to treat or preven t disorders ans conditions mediated by the histamine H4 receptor.