Forms of rifaximin and uses thereof

1. A rifaximin polymorph Form Xi or a salt, or hydrate form thereof, having an X-ray powder diffraction comprising peaks, in terms of 2Θ, at two or more of: about 5.73, about 6.57, about 6.85, about 7.07, about 7.86, about 8.26, about 8.98, about 9.86, about 12.60, about 13.34, about 14.17, about 14.49, about 15.46, about 16.45, about 16.96, about 17.78, about 19.19, about 20.37, about 20.66, about 21.33, about 21.86 and about 22.88.

2. The rifaximin polymorph Form Xi according to claim 1 , wherein the rifaximin Form Xi contains less than 5% by weight impurities.

3. The rifaximin polymorph Form Xi according to claim 1 , wherein the rifaximin Form Xi is at least 50% pure, at least 75% pure, at least 80% pure, at least 90% pure, at least 95% pure, or at least 98% pure.

4. The rifaximin polymorph Form Xi according to claim 1 , wherein the rifaximin Form Xi is formulated as coated or uncoated tablets, hard or soft gelatin capsules, sugar-coated pills, lozenges, wafer sheets, pellets, or powders in sealed packet.

5. A pharmaceutical composition comprising the rifaximin polymorph Form Xi according to claim 1 , and a pharmaceutically acceptable carrier.

6. A method of treating a bowel related disorder, comprising administering to a subject in need thereof and an effective amount of the rifaximin polymorph Form Xi according to claim 1 .

7. A method of producing the rifaximin polymorph Form Xi according to claim 1 , comprising:

dissolving rifaximin to form a first mixture;

heating the first mixture to a temperature above a seeding temperature;

cooling the first mixture to the seeding temperature;

adding a slurry of rifaximin form eta to form a second mixture;

heating the second mixture such that the seeding temperature is maintained;

cooling the second mixture to a sub-ambient temperature; and

filtering the second mixture to obtain Form Xi, which is optionally washed and dried.

8. The method of claim 7 , wherein the temperature about a seeding temperature is about 60° C.

9. The method of claim 7 , wherein the seeding temperature is about 45° C.

10. The method of claim 7 , wherein the sub-ambient temperature is about 0° C.

11. The method of claim 7 , wherein the dissolving of rifaximin to form a first mixture is performed with ethanol.

12. A rifaximin polymorph Form Eta or a salt, or hydrate form thereof, having an X-ray powder diffraction comprising peaks, in terms of 20, at two or more of: about 6.1, about 7.3, and about 7.5; or about 6.1, about 7.3, and about 7.9; or about 6.1, about 7.3, and about 8.8; or about 6.1, about 7.3, and about 12.7; or about 6.1, about 7.5, and about 8.8; or about 6.1, about 7.5, and about 7.9; or about 5.3, about 6.1, and about 7.3; or about 5.3, about 6.1, and about 7.9; or about 5.3, about 6.1, and about 12.7; or about 5.3, about 6.1, and about 7.5; or about 5.3, about 6.1, and about 8.8; or about 6.1, about 7.3, about 7.5, about 7.9, about 8.8, and about 12.7; or about 5.3, about 6.1, about 7.3, about 7.5, about 7.9, about 8.8, and about 12.7; or about 5.3, about 6.1, about 7.3, about 7.9, about 8.8, and about 12.7; or about 5.3, about 6.1, about 7.3, about 7.5, about 8.8, and about 12.7; or about 5.3, about 6.1, about 7.3, about 7.5, about 7.9, about 8.8, and about 12.7.

13. The rifaximin polymorph Form Eta according to claim 12 , wherein the rifaximin Form Eta contains less than 5% by weight impurities.

14. The rifaximin polymorph Form Eta according to claim 12 , wherein the rifaximin Form Eta is at least 50% pure, at least 75% pure, at least 80% pure, at least 90% pure, at least 95% pure, or at least 98% pure.

15. The rifaximin polymorph Form Eta according to claim 12 , wherein the rifaximin Form Eta is formulated as coated or uncoated tablets, hard or soft gelatin capsules, sugar-coated pills, lozenges, wafer sheets, pellets, or powders in sealed packet.

16. A pharmaceutical composition comprising the rifaximin polymorph Form Eta according to claim 12 , and a pharmaceutically acceptable carrier.