| abstract |
Amorphous rifaximin with improved dissolution rate useful for the treatment of bowel-related diseases such as diarrhea, traveler's diarrhea, microbial-related diarrhea, Crohn's disease, chronic pancreatitis, pancreatic insufficiency and / or colitis, and production thereof Providing a method. A method for producing amorphous form of rifaximin characterized by the XRPD pattern shown in FIG. 1 according to a) to h) below. a) Rifamycin S is reacted with 2-amino-4-picoline. b) Add iodine and subsequently the reducing agent. c) Adjust the pH of the reaction mass between 1.5 and 2.5 under stirring. d) Extract with an organic solvent and concentrate the organic layer. e) Strip the residue obtained in step d) with n-heptane to produce a residue. f) Stir the residue obtained in step e) with dichloromethane, heptane, or a mixture thereof to obtain a solid. g) Filter the solid and wash with solvent. And h) the solid is dried at a temperature below 40 ° C. [Selection] Figure 1 |