Friulchem Spa

Evultis Sa

Silvia Moiana

Disma Mazzola

Germano Coppi

Alessandro Mazzola

Process for the preparation of rifaximin, pseudo-crystalline rifaximin and a new pseudo-crystalline form of rifaximin with fewer impurities obtained thereby.

Process for the synthesis of rifaximin and a new pseudo-crystalline form of rifaximin obtained thereby

The present invention is directed to a process for producing non-genotoxic Diacetylrhein (Diacerein), comprising: 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 1 ppm, and suitable for the preparation of pharmaceutical formulations, in particular capsules, for human and veterinary use, in agreement with the current Health Authorities request.

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Cantu-Como, Italy

Silvia Moiana