RIFAXIMINE POLYMORPHOUS FORMS, METHODS FOR THEIR PREPARING AND THEIR USING IN MEDICINAL PREPARATIONS Russian patent published in 2006 - IPC C07D498/22 A61K31/395 A61K31/4353 A61P31/00 

FIELD: medicine, antibiotics, pharmacy.

SUBSTANCE: invention relates to new crystalline polymorphous forms of antibiotic rifaximine (the International nonpatented name is MHH) and named as rifaximine-α and rifaximine-β, and a low crystalline form named as rifaximine-γ. Indicated rifaximine-α comprises water in the amount less 4.5% and shows roentgen powdery diffractogram demonstrating peaks at the diffraction angle values 2θ 6.6°; 7.4°; 7.9°; 8.8°; 10.5°; 11.1°; 11.8°; 12.9°; 17.6°; 18.5°; 19.7°; 21.0°; 21.4° and 22.1°. Rifaximine-β comprises water in the amount above 4.5% and shows roentgen powdery diffractogram demonstrating peaks at the diffraction angle values 2θ 5.4°; 6.4°; 7.0°; 7.8°; 9.0°; 10.4°; 13.1°; 14.4°; 17.1°; 17.9°; 18.3° and 20.9°. Rifaximine-γ comprises water in the amount from 1.0% to 2.0% and shows roentgen powdery diffractogram demonstrating amorphous pattern mainly and some significant peaks at diffraction angle values 2θ 5.0°; 7.1° and 8.4°. Also, invention relates to composition based on thereof possessing the antibiotic effect and to methods for their preparing. Method involves dissolving crude rifaximine at heating in ethyl alcohol and inducing crystallization process of product by addition of water at the definite temperature for definite time interval followed by drying under controlled conditions up to the specific water content in the end product. Invention provides preparing new crystalline polymorphous forms of rifaximine that are useful in preparing medicinal preparations for oral and topical using and possessing the antibiotic effect.

EFFECT: improved preparing method.

24 cl, 3 dwg, 10 ex