Involvement of blockade of leukotriene B-4 action in anti-pruritic effectsof emedastine in mice

The anti-pruritic activity of emedastine difumarate was studied in mice. Em edastine (0.03-0.3 mg/kg) inhibited scratching induced by intradermal injec tion of histamine (100 nmol/site). Scratching induced by substance P (100 n mol/site) and leukotriene B-4 (0.03 nmol/site), but not by serotonin (100 n mol/site), was also suppressed by emedastine (0.03-0.3 mg/kg). Intradermal injection of substance P increased the cutaneous concentration of leukotrie ne B-4, which was not affected by emedastine. These results suggest that th e inhibition by emedastine of substance P-induced itch-associated response is mediated by the blockade of leukotriene B-4 action. Anti-leukotriene B-4 action, as well as the anti-histamine action, may contribute to the anti-p ruritic effects of emedastine. (C) 2000 Elsevier Science B.V. All rights re served.