Pyrazolopyridine derivatives (I), their salts, solvates and prodrugs are new. Pyrazolopyridine derivatives of formula (I), their salts, solvates and prodrugs are new. [Image] A : N or N +>；O ->；； R 1>；phenyl or het (optionally substituted with one or more substituents of R-a or R-b)； R 2>；het (optionally substituted with one or more substituents of R-a or R-b)； either R 3>；H, Cy (optionally substituted with one or more substituents of R-a or R-b)； or R 3>；1-6C alkyl (optionally substituted with one or more substituents of R-b or Cy*) Cy* : optionally substituted with one or more substituents of R-b or R-c； R 4>；H, R-a, halo, OR-a', OCOR-a, OSO 2R-a, OCONR-aR-a', NO 2, CN, COR-a', CO 2R-a', CONR-a'R-a', NR-a'R-a', NR-a'COR-a', NR-a'CONR-a'R-a', NR-a'CO 2R-a, NR-a'SO 2R-a, SR-a', SOR-a, SO 2Ra or SO 2NR-a'R-a'； R 5>； = H or R-f (where R 5>； can be placed on any of the 2 N of the pyrazole ring)； R-a : 1-6C alkyl, 2-6C alkenyl, 2-6C alkynyl or Cy (where the groups 1-6C alkyl, 2-6C alkenyl or 2-6C alkynyl optionally substituted with one or more substituents of R-b or Cy*, and where any of the groups Cy or Cy* optionally substituted with one or more substituents of R-b or R-c)； R-a' : H or R-a； R-b : halo, OR-c', OCOR-c, OSO 2R-c, OCONR-cR-c', NO 2, CN, COR-c', CO 2R-c', CONR-c'R-c', CONR-c'NR-c'R-c', NR-c'R-c', NR-c'COR-c', NR-c'CONR-c'R-c', NR-c'CO 2R-c, NR-c'SO 2R-c, SR-c, SOR-c, SO 2R-c, SO 2NR-c'R-c', C(NR-c')NR-c'R-c', C(NSO 2NR-c'R-c')NR-c'R-c', C(NOR-c')R-c', C(NNR-c'R-c')R-c', NR-c'C(NR-c')NR-c'R-c' or NR-c'C(NCN)NR-c'R-c'； R-c : 1-6C alkyl, 2-6C alkenyl, 2-6C alkynyl or Cy (where all these groups optionally substituted with one or more substituents R-d)； R-c' : H or R-c； R-d : halo, R-e, OR-e', OCOR-e, OSO 2R-e, OCONR-eR-e', NO 2, CN, COR-e', CO 2R-e', CONR-e'R-e', CONR-e'NR-e'R-e', NR-e'R-e', NR-e'COR-e', NR-e'CONR-e'R-e', NR-e'CO 2R-e, NR-eSO 2R-e, SR-e', SOR-e, SO 2R-e, SO 2NR-e'R-e', C(NR-e')NR-e'R-e', C(NSO 2NR-e'R-e')NR-e'R-e', C(NOR-e')R
