ABSTRACT
Most recently, we demonstrated the antipruritic activity of TRK-820 in morphine-induced (10), histamine-induced, and substance P-induced mouse scratching models (1 I). In these models, TRK-820 was more effective than antihistamines such as ketotifen or chlorpheniramine, suggesting that TRK-820 has efficacy against antihistamine-resistant pruritus via the Kopioid receptor. In the present chapter, we describe several studies we have conducted to assess the antipruritic effect of this compound in animals.
