The disclosure relates to crystalline salt forms, namely the hemi-edisylate and hemi-napadisylate forms of 4&rsquo-{ 2-ethoxy-4-ethyl-5-[((S)-2-mercapto-4-methylpentanoylamino)methyl]imidazol-1-ylmethyl} -3&rsquo-fluorobiphenyl-2-carboxylic acid. The disclosure also relates to pharmaceutical compositions comprising these crystalline forms, methods for forming them and methods of using the crystalline forms in medicaments for the treatment of diseases such as heart disease or hypertension.