A compound represented by the formula (I), salt thereof, or hydrate thereof has an excellent anti-pruritic effect and an excellent effect in terms of metabolism. The topical formulation of the present invention has excellent skin absorption properties of the compound represented by the formula (I), salt thereof, or hydrate thereof. Furthermore, the topical formulation of the present invention is excellent in stability because ingredients are hardly bled after long-term storage. wherein R represents hydroxyl, C 1-6 alkoxy optionally substituted with C 1-6 alkoxy, or amino optionally substituted with C 1-6 alkyl.以式(I)所示化合物或其鹽或此等之水合物係可具有優異之止癢效果，且可在代謝方面發揮優異之效果者。本發明之外用劑係以式(I)所示化合物或其鹽或此等之水合物可具有極優異之對皮膚吸收性者。又，本發明之外用劑係既使長期間保存亦具有配合成份不易分離之安定性上優異點。[式中R示羥基、可被C1~C6烷氧基所取代之C1~C6烷氧基、或可被C1~C6烷基所取代基之胺基]。
