Use of a neutral EC endopeptidase inhibitor. 3.4. 24.11. in the manufacture of a medicament for the treatment, improvement or prevention of contrast-induced nephropathy in a subject in need of such treatment, in which the neutral endopeptidase inhibitor is: a) a compound 5 of Formula II: ** Formula ** or a pharmaceutically acceptable salt thereof, wherein: R1 is C1-7 alkyl； for each occurrence, R2 is independently C1-7 alkyl, NO2, CN, halo, C3-7 cycloalkyl, hydroxy, C1-7 alkoxy, halo- C1-7 alkyl, NRbRc, C6-10 aryl, heteroaryl or heterocyclyl； wherein Rb and Rc for each occurrence, are independently H or C1-7 alkyl； R3 is A1C (O) X1 or A2-R4； R4 is C6-10 aryl or a heteroaryl, which may be monocyclic or bicyclic and which may be optionally substituted with one or more substituents independently selected from hydroxy, hydroxyC 1-7 alkyl, NRbRc, nitro, C1-7 alkoxy, halo, C1-7 alkyl, halo- C1-7 alkyl, C2-7 alkenyl, C6-10 aryl, heteroaryl, -C (O) C1-7 alkyl, -NHS (O) 2-C1-7 alkyl, -SO2 C1-alkyl 7 and benzyl； R5 is H, halo, hydroxy, C1-7 alkoxy, halo, C1-7 alkyl or halo- C1-7 alkyl； and X and X1 are independently OH, -O-C1-7 alkyl, -NRbRc, -NHS (O) 2-C1-7 alkyl, -NHS (O) 2-benzyl or -O-C6-10 aryl； wherein alkyl is optionally substituted with one or more substituents independently selected from the group consisting of aryl, heteroaryl, heterocyclyl, -C (O) NH2, -C (O) NH-C1-6 alkyl, and -C (O ) N (C1-6 alkyl) 2； A1 is a link； or A1 is a linear or branched C2-6 alkenylene； or A1 is a linear C1-4 alkylene in which one or more carbon atom or atoms is / are replaced with a heteroatom selected from O, NRa； and A1 is optionally substituted with one or more substituents independently selected from the group consisting of halo and C1-7 alkyl； wherein Ra for each occurrence, is independently H, C1-7 alkyl or CH2C (O) OH； or A1 is a C3-7 cycloalkyl, a heterocyclyl, a phenyl or a heteroaryl in which phenyl and heteroaryl are optionally substituted with one or more substituents indepen
