Polymorphic forms alpha, beta and gamma of rifaximin

Abstract

Crystalline polymorphous forms of rifaximin (INN) antibiotic named rifaximin α and rifaximin β, and a poorly crystalline form named rifaximin γ, useful in the production of medicinal preparations containing rifaximin for oral and topical use and obtained by means of a crystallization carried out by hot-dissolving the raw rifaximin in ethyl alcohol and by causing the crystallization of the product by addition of water at a determinate temperature and for a determinate period of time, followed by a drying carried out under controlled conditions until reaching a settled water content in the end product, are the object of the invention.

What is claimed is: 
     
         1 . Rifaximin in polymorphic form α. 
     
     
         2 . Rifaximin in polymorphic form β. 
     
     
         3 . Rifaximin in polymorphic form γ.