A compound according to formula (I)
wherein R1 is hydrogen, cyclopropyl, or pyrazolyl, wherein said pyrazolyl is optionally substituted by one or two methyl groups; or a pharmaceutically acceptable salt thereof.
一种符合式 (I) 的化合物,其中 R1 是氢、环丙基或
吡唑基,其中所述
吡唑基任选被一个或两个甲基取代;或其药学上可接受的盐。