Polymorphous forms of rifaximin, processes for their production and use thereof in medicinal preparations

摘要

Crystalline polymorphous forms of the rifaximin (INN) antibiotic named rifaximin alpha and rifaximin beta, and a poorly crystalline form named rifaximin gamma have been discovered. These forms are useful in the production of medicinal preparations for oral and topical use and can be obtained by means of a crystallization process carried out by hot-dissolving the raw rifaximin in ethyl alcohol and by causing the crystallization of the product by the addition of water at a determinate temperature and for a determinate period of time. The crystallization is followed by drying carried out under controlled conditions until a specific water content is reached in the end product.