The use of a compound represented by the following general formula (I) or a pharmaceutically acceptable salt thereof
wherein each of R₁, R₂ and R₃ which may be same or different is hydrogen or alkyl; and R and X have the meanings given in the specification, for the preparation of a medicament which is an adenosinedeaminase inhibitor is disclosed. Some of the compounds of formula (I) are novel compounds. They may be used for the making of a medicament which is for the prevention or therapy of ischemic heart diseases, diseases caused by cerebrovascular disorders, renal diseases and allergic diseases and of post-operative complicated diseases involved with activated oxygen which is generated in ischemic areas during the recirculation of blood after operations.