Patent ID: 8598183

Claim:
A crystalline sodium salt of the compound of the following formula (1): having: (a) an X-ray powder diffraction pattern comprising peaks at 7.5 and 20.4 degrees 2θ (±0.2 degrees 2θ) when measured using CuKα radiation; or (b) a 13 C solid state NMR spectrum comprising peaks at a chemical shift of 176.8 and 168.4 ppm (±0.2 ppm); or (c) both an X-ray powder diffraction pattern comprising peaks at 7.5 and 20.4 degrees 2θ (±0.2 degrees 2θ) when measured using CuKα radiation and a 13 C solid state NMR spectrum comprising peaks at a chemical shift of 176.8 ppm and 168.4 ppm (±0.2 ppm).