The present invention addresses the problem of finding a novel medicine that has an excellent tryptophanase inhibitory effect, that suppresses deterioration of renal functions by reducing indoxyl sulfate production in blood, and that contributes to kidney preservation. Provided is a medicinal composition containing, as an active ingredient, a compound represented by formula (I) or a pharmacologically acceptable salt thereof. [In the formula, R1 and R2 may be the same or different, and each represent a C1-C6 alkyl group, a halogeno C1-C6 alkyl group, or a C3-C6 cycloalkyl group； n is 0, 1, or 2； X represents a C1-C6 alkyl group, a C3-C6 cycloalkyl group, a halogen atom, or the like； Y represents a hydrogen atom, a C1-C6 alkoxy group, a C3-C6 cycloalkoxy group, or a halogeno C1-C6 alkoxy group].本發明之課題係發現一種新穎的醫藥，其具有優異的色胺酸酶抑制作用，藉由減低血中的吲哚酚硫酸的產生而抑制腎功能的惡化，並維持腎臟。解決手段係一種醫藥組成物，其含有下式所示之化合物或其藥理上可容許的鹽作為有效成分，[式中，R1及R2相同或相異地為C1-C6烷基、鹵C1-C6烷基或C3-C6環烷基，n為0、1或2，X為C1-C6烷基、C3-C6環烷基、鹵素原子等，Y為氫原子、C1-C6烷氧基、C3-C6環烷氧基或鹵C1-C6烷氧基]。
