POLYMORPHIC FORMS OF RIFAXIMIN, PROCESSES FOR THEIR PRODUCTION AND USE THEREOF IN MEDICINAL PREPARATIONS

摘要

Crystalline polymorphic forms of rifaximin (INN), referred to as rifaximin alpha and rifaximin beta, and a poorly crystalline form referred to as rifaximin gamma, useful in the production of medicaments containing rifaximin for the oral and topical use and obtained by means of a crystallization process carried out by hot-dissolving the raw rifaximin in ethyl alcohol and causing the crystallization of the product by addition of water at a fixed temperature and for a fixed period of time, followed by drying under controlled conditions until reaching a precise water content in the end product, are the object of the invention.