A compound of formula (I) wherein: wherein X4 is NR1 or S _ X1 is CR3 X2 is NRe or O, provided that X2 is NRe where X1 is N X3 is N to treat or prevent disorders ans conditions mediated by the histamine H4 receptor.Linvention concerne des composés hétérocycliques ainsi que leurs procédés de fabrication et dutilisation.