A crystalline freebase of 4- {2-ethoxy-4-ethyl-5-[((S)2-mercapto-4- methylpentanoylamino)methyl]imidazol-1 -ylmethyl} -3 -fluorobiphenyl-2-carboxylic acid, characterized by a powder x-ray diffraction pattern comprising diffraction peaks at 29 values of 6.66±0.20,9.8±0.20, and 18.12±0.20.