Compounds of formula (I):whereinR1represents a hydrogen atom or a heterocyclic, cyano, alkoxycarbonyl, alkylsulphonylaminoalkyl orN-hydroxycarboximidamide group.Medicaments.本發明係關於式(I)之化合物:其中R1表示氫原子或雜環基、氰基、烷氧基羰基、烷基磺醯基胺基烷基或N-羥基甲脒(carboximidamide)基團。本發明係關於藥劑。