Izuforant (JW1601) (Compound 24) is an orally active histamine H4 receptor ( H4R ) antagonist with an IC 50 of 36 nM against human H4R. Izuforant also shows binding affinity of human serotonin 3 receptor ( h5-HT3R ) with an IC 50 of 9.1 μM. Izuforant exhibits strong anti-pruritic and anti-inflammatory efficacies.