The present invention provides a preparation having an improved lightfastness and oxidation resistance of a 4,5-epoxymorphinan derivative (particularly NAL-F) for oral pruritus-ameliorating drug. A preparation comprises a 4,5-epoxymorphinan derivative or the derivative with a pharmacologically acceptable acid neutralizing salt as ingredient (a), a polyethylene glycol as ingredient (b), and at least one pigment selected from the group consisting of naphthol based azo dye, xanthene pigment, and blue No. 2 as ingredient (c), or a tocopherol as ingredient (d).本發明提供一種經口之搔癢症改善藥4,5-環氧嗎啡喃衍生物(尤其是NAL-F)之具有經改良耐光性及耐氧化性之製劑。 一種製劑,其含有作為(a)成分之4,5-環氧嗎啡喃衍生物或其與藥理學上可容許之酸之中和鹽,作為(b)成分之聚乙二醇,作為(c)成分之選自萘酚系偶氮色素、氧雜蒽(xanthene)色素、藍色1號之至少一種色素,及作為(d)成分之生育酚。無
