Involvement of substance P in scratching behaviour in an atopic dermatitis model

Substance P is speculated to be a key mediator of itching in atopic dermatitis, possibly acting via the tachykinin NK1 receptor. Thus, we examined the effect of a tachykinin NK1 antagonist, BIIF 1149 CL, on scratching behaviour in a picrylchloride-induced dermatitis model in NC/Nga mice. BIIF 1149 CL ((S)-N-[2-[3,5-bis(trifluoromethyl) phenyl]ethyl]-4-(cyclopropylmethyl)-N-methyl-alpha-phenyl-1-piperazineacetamide, monohydrochloride, monohydrate) at a dose of 100 mg/kg, p.o., significantly inhibited scratching behaviour immediately after administration, and the effect continued up to 6 h. The results suggest that clinical trials of tachykinin NK1 antagonists for the treatment of itching in atopic dermatitis patients would be warranted.