To provide a technique for improving the stability of a halogenated isoquinoline derivative with respect to light in an aqueous composition. A pharmaceutical preparation that is obtained by having an aqueous composition, which contains a compound represented by general formula (1), a salt thereof or a solvate of the compound or salt, contained in a package that blocks light having a wavelength of 300-335 nm. (In the formula, X represents a halogen atom.)本發明在於提供：改善鹵化異喹啉衍生物在水性組成物中對光之安定性的技術。本發明的醫藥製劑，係將含有下述一般式(1)：[式中、X係表示鹵原子。]所示化合物或其鹽或該等的溶劑合物之水性組成物，收容於可阻斷波長300~335nm光線的包裝體中。
