Usefulness of NOA mouse in the evaluation of antipruritic effect of external medicines and significance of combined formulation of local anesthetics and antihistamine agent in external medicines

摘要

As a typical method to evaluate the antipruritic effects of external medicines, scratching behavior is examined following subcutaneous administration of Compound 48/80, a histamine-releasing agent, to the shaved and clipped skin of haired mouse. However, this method has the disadvantage that scratch responses possibly due to the remains of applied external medicine, adhered to the remaining hairs after hair shaving and clipping or adhered to the surrounding hair, are observed in the animals. In the present study, we have used NOA mouse that has no growth of pelage hair in order to evaluate the significance of combined formulation of local anesthetics and antihistamine agent in external medicines. The results showed the significant usefulness of NOA mouse in the evaluation of antipruritic effect of external medicines. Each local anesthetics and antihistamine agent formulated in the external medicine showed antipruritic effect, and when both anesthetics and antihistamine were formulated together, the effect was increased in an additive manner. In particular, the effect of combined anesthetics and antihistamine was markedly increased when applied prior to the treatment with histamine-releasing agent, indicating the significance of the combined formulation of local anesthetics and antihistamine.