The present invention provides compounds represented by below formula (1) and pharmacological acceptable salts thereof as an active ingredient of a drug for inducing hard bone and/or cartilage assimilation. This medicine has high metabolism stability to prevent or cure symptoms like osteoporosis, bone loss, alveolar bone defects, variations of joint disease, articular cartilage defects, non-powered bone disease, achondroplasia, hypochondroplasia, osteomalacia and bone fractures. (in the disclosed formula, R1, R2, R3, R4 are synonymous to items described in the range of patent application).本發明係一種包含以下列一般式(1)表示之化合物或其藥理學上容許鹽為有效成分之用於誘導硬骨及/或軟骨同化作用的藥物:(式中,R1、R2、R3、R4與申請專利範圍記載者同義)。
