Therapeutic and Prophylactic Effects of Emedastine Difumarate on Atopic Dermatitis-like Lesions in NC/Nga Mice

Abstract

The NC/Nga (NC) mouse, an animal model for human atopic dermatitis, develops eczematous lesions when raised in a conventional environment. In the present study, the therapeutic and prophylactic effects of emedastine difumarate, an anti-allergy drug, was examined using NC/Nga mice. The experimental mouse population was divided into those reared in a conventional environment, which had developed eczematous lesions, and those reared in a sterile environment and recently transferred to a conventional environment, which had not yet developed any symptoms. Emedastine difumarate was administered in water to both populations for 10 or 14 weeks in dosages of 1 mg/kg/day or 10 mg/kg/day, respectively, and the condition of these mice was compared with that of untreated controls. The effect of the drug was evaluated by scoring skin manifestations, such as erythema, edema, bleeding, erosion, hair loss, and dryness. The frequency of scratching during 30 min, plasma IgE level, and the number of mast cells and eosinophils in the skin tissue were also examined. Prophylactic administration of emedastine difumarate significantly suppressed the development of skin lesions and scratching at 1 mg/kg/day and more strongly at 10 mg/kg/day throughout the experiment for 14 weeks. Therapeutic administration of emedastine difumarate at 10 mg/kg/day significantly suppressed eczematous skin lesions and led to reduced scratching for 10 weeks. Administration of emedastine difumarate at 10 mg/kg/day to both mouse populations significantly suppressed the infiltration of mast cells and eosinophils into the skin but did not affect the plasma IgE level. These results indicate that the NC/Nga mouse is an excellent animal model for evaluating the effect of anti-allergy medications and that emedastine difumarate has significant therapeutic and prophylactic effects for eczematous skin lesions in NC/Nga mice.