Topical E6005, a novel phosphodiesterase 4 inhibitor, attenuates spontaneous itch‐related responses in mice with chronic atopy‐like dermatitis

Atopic dermatitis is a chronic inflammatory cutaneous disease with difficult‐to‐treat pruritus. Although phosphodiesterase ( PDE ) 4 inhibitors have an anti‐inflammatory effect on inflammatory skin diseases, such as atopic dermatitis, their acute antipruritic activities remain unclear. Therefore, in this study, we examined whether E 6005, a novel PDE 4 inhibitor, has antipruritic activity in dermatitis, using a mouse model of atopic dermatitis ( NC / N ga mice). A single topical application of E 6005 inhibited spontaneous hind‐paw scratching, an itch‐associated response and spontaneous activity of the cutaneous nerve in mice with chronic dermatitis. The cutaneous concentration of c AMP was significantly decreased in mice with chronic dermatitis, and this decrease was reversed by topical E 6005 application. These results suggest that E 6005 increases the cutaneous concentration of c AMP to relieve dermatitis‐associated itching. Thus, E 6005 may be a useful therapy for pruritic dermatitis such as atopic dermatitis.