Involvement of blockade of leukotriene B4 action in anti-pruritic effects of emedastine in mice

The anti-pruritic activity of emedastine difumarate was studied in mice. Emedastine (0.03-0.3 mg/kg) inhibited scratching induced by intradermal injection of histamine (100 nmol/site). Scratching induced by substance P (100 nmol/site) and leukotriene B-4 (0.03 nmol/site), but not by serotonin (100 nmol/site), was also suppressed by emedastine (0.03-0.3 mg/kg). Intradermal injection of substance P increased the cutaneous concentration of leukotriene B-4, which was not affected by emedastine. These results suggest that the 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-pruritic effects of emedastine. (C) 2000 Elsevier Science B.V. All rights reserved.