*Corresponding Author Address: Ana Carolina Kogawa, Faculdade de Ciências Farmacêuticas de Araraquara, UNESP, Rodovia Araraquara-Jaú, km 1, CEP 14801-902, Araraquara, SP, Brazil.E-mail: ac_kogawa@yahoo.com.br Journal of Pharmaceutical and Biological Sciences ISSN: 2320-1924; CODEN: JPBSEV Published by Atom and Cell Publishers © All Rights Reserved Available online at: http://www.jpabs.org/ Original Article Impact of rifaximin potency after treatment with different solvents Ana Carolina Kogawa* and Hérida Regina Nunes Salgado Department of Pharmaceutics, School of Pharmaceutical Sciences of Araraquara, Univ Estadual Paulista - UNESP, Araraquara, São Paulo, Brazil Received: 23-03-2017 / Revised Accepted: 24-04-2017 / Published: 26-04-2017 ABSTRACT Rifaximin is an oral antibiotic used for the treatment of hepatic encephalopathy, ulcerative colitis, irritable bowel syndrome, Clostridium difficile, travelers' diarrhea and acute diarrhea. Production of rifaximin involves the use of different solvents. The performance of these solvents can affect the activity of this antimicrobial. The general objective of this work is to show the importance in the rigorous production of rifaximin raw material. The specific objectives of this work are to show that the use of different solvents or even a modification in the process of obtaining the raw material can lead to different activities of powder. A purposeful change in the process of obtaining the rifaximin raw material by recrystallization, using different solvents, resulted in significant changes in antimicrobial activity. This is an alert to the production of pharmaceutical inputs. The process of obtaining raw material must be standardized, aiming not only the quality of the medicine, but also, aiming the consequences of the use of non-quality medicines that generate a vicious cycle in the public health system. Keywords: rifaximin, antibiotic, raw material, antimicrobial activity, quality. INTRODUCTION Rifaximin (Fig. 1) is a antimicrobial used for thetreatment of hepatic encephalopathy, ulcerative colitis, irritable bowel syndrome, Clostridium difficile, travelers' diarrhea and acute diarrhea [1- 3]. Figure 1. Chemical structure of rifaximin (CAS 80621-81-4). On the market, tablets of rifaximin in crystalline form α are found, its systemic bioavailability is limited and this is one of the advantages of the use of this antimicrobial, which acts locally. The amorphous form showed significantly higher bioavailability and therefore lower tolerability [4]. The production of rifaximin involves the use of the following solvents: purified water, ethyl alcohol, chloroform, dichloromethane and ethyl acetate [5- 8]. Does the change in any of these solvents, the time of exposure to them during the production of this raw material or a small change in the process of obtaining it can lead to differences in the activity of this antimicrobial? This work shows the importance of the rigorous production of the raw material of rifaximin against the results of antimicrobial activity obtained. EXPERIMENTAL Material: Rifaximin, form α, acquired of the company NutraTech Development Limited (China), was used. Method: Rifaximin was solubilized in purified water, ethyl alcohol, acetone, chloroform, dichloromethane and ethyl acetate and re-obtained by recrystallization. The materials obtained are described in Table 1 [9].