i) transformation of raw Diacerein (or raw Rhein), into a water-soluble salt ii) adsorption of the salt Diacerein (or Rhein) solution on a hydrophobic resin iii) washing with an appropriate solvent to eliminate the impurities (in particular the genotoxic impurities) iv) elution to recover Diacereinor Rhein v) if the process is applied to Rhein, its transformation to Diacerein by acetylation vi) acidification of purified Diacerein and its recovery, and drying. The invention is also directed to non-genotoxic Diacerein obtained by the process of the invention, in which the total content of genotoxic impurities is below 1ppm, and suitable for the preparation of pharmaceutical formulations, in particular capsules, for human and veterinary use, in agreement with the current Health Authorities request.
