Rifaximin
AssigneeCipla Limited
InventorsDharmaraj Ramachandra Rao, Rajendra Narayanrao Kankan, Manjinder Singh Phull, Muruti Ghagare
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Abstract
Amorphous rifaximin, methods of making it, and pharmaceutical compositions containing it. Also described are methods of converting amorphous rifaximin to crystalline rifaximin and vice versa.
Claims14
A process for the inter-conversion of crystalline rifaximin, said process comprising:
- a) dissolving γ form rifaximin in a suitable solvent at 40-60° C.;
- b) combining the solution with water and allowing to cool;
- c) filtering and washing the resulting solid, and
- d) drying the resulting solid at a temperature from 80-110° C. to obtain the β form of rifaximin.
A process for converting amorphous rifaximin to crystalline γ form rifaximin, said process comprising dissolving amorphous rifaximin in an organic solvent, then drying the rifaximin mixture at a temperature from 100 to 110° C. to yield γ form rifaximin.
A process for converting amorphous rifaximin to crystalline β form rifaximin, said process comprising combining the amorphous rifaximin with a mixture of a water-miscible organic solvent and water, then drying the rifaximin mixture at a temperature from 80 to 110° C. for 10-15 hours to yield β form rifaximin.
A process for converting a crystalline form of rifaximin to an amorphous form of rifaximin, said process comprising:
- (i) dissolving the crystalline rifaximin in a suitable solvent,
- (ii) filtering and washing the filtrate with a suitable solvent,
- (iii) concentrating the residue at 40-60° C. to form a rifaximin residue,
- (iv) stripping rifaximin residue with n-heptane;
- (v) filtering and washing the solid with n-heptane;
- and
- (vi) drying the solid at a temperature below 40° C. to obtain amorphous rifaximin.
Dependencies are inferred from the claim text.