New Rifaximin Samples:
Obtaining, Characterization, Solubility Study and Microbiological Evaluation

Ana Carolina Kogawa, Universidade Estadual Paulista, Araraquara, Brasil (ac_kogawa@yahoo.com.br)
Leena Peltonen, Universidade Estadual Paulista, Araraquara, Brasil
Hérida Regina Nunes Salgado, Universidade Estadual Paulista, Araraquara, Brasil
Marlus Chorilli, Universidade Estadual Paulista, Araraquara, Brasil

Rifaximin is an oral antimicrobial drug used for a wide range of ages, from adults to children, since it is indicated for the treatment of hepatic encephalopathy, travelers' diarrhea, irritable bowel syndrome, Clostridium difficile, ulcerative colitis and acute diarrhea. It is marketed as 200 mg tablets. The daily dose may be up to 800 mg (2 tablets twice a day). The success of pharmacotherapy will depend on correct fulfillment of drug administration, however it becomes difficult when the tablets are large and the doses are frequent. According to the Biopharmaceutic Classification System (BCS), rifaximin belongs to Class IV. It is both poorly soluble and poorly permeable. Thus, solubility of rifaximin was studied by the complexation to β-cyclodextrin using (i) phase solubility diagram and (ii) malaxation and (iii) decreasing particle size by wet milling. At the same time as the solubility increases, lower doses of rifaximin are possible and this facilitates patient adherence to treatment. The samples formed were characterized by spectrophotometry in the infrared region (FT-IR), differential scanning calorimetry (DSC) and X-ray diffraction (XRD) and the evaluation of their antimicrobial potencies were determined by microbiological turbidimetry. The samples obtained in all techniques were more soluble than the free drug, they presented higher thermal stability and the antimicrobial potencies of all formulations were approximately 100 %. It is fundamental to highlight that the treatment failure not only affects the quality of life of the patients, but also contributes significantly to the economic burden of the health system. This promising research opening can lead more efficient use of rifaximin in drug therapy, which is important for public health. These findings are extremely interesting, both from a technological and financial point of view.

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Abstract Reference & Short Personal Biography of Presenting Author

My name is Ana Carolina Kogawa, I am Pharmaceutical-Biochemistry by UNESP and Master and PhD in Pharmaceutical Sciences also by UNESP. I have Black Belt-Six Sigma Training, which helped me enormously in performing activities, planning experiments, problem solving, and teamwork. Currently, I carry out post-doctoral research at UNESP in the areas of Pharmaceutical Technology and Physico-chemical and Microbiological Quality Control of Drugs and Medicines.

So far, I have more than 60 scientific articles published. During my Master, PhD and post-doctoral studies I participated in national and international events through presentation of poster and oral papers in London (UK), Osaka (Japan), Valencia (Spain), Rome (Italy), Lisbon (Portugal), Berlin (Germany), Paris (France), Ghent and Liege (Belgium), Cordoba and Rosario (Argentina), Cartagena de las Indias (Colombia) and several cities in Brazil. I am a reviewer of 22 international journals, which are described in the curriculum. I co-supervised and co-supervise undergraduate, master and doctoral students. My index h = 10 and Index i10 = 10.

My area of activity is the physico-chemical and microbiological quality control of drugs and medicines aimed at green analytical chemistry and everything that involves it. Our concern for quality is multidimensional. It covers the health of the analyst, the chosen reagents, the treatment of residues, the amount of residues formed, the toxicity of the reagents, the accessories used, the analysis time, the chosen technique, the equipment of protection, physical and emotional well-being, the environment and, of course, safe and effective pharmaceutical analyzes.

My projects also aim to work in a multidisciplinary way interacting in different laboratories: Quality Control and Pharmaceutical Technology; different equipment: spectrophotometer, chromatograph, dissolutor, X-ray diffractor; different methods: wet milling, complexation, spectrophotometry in the ultraviolet, visible and infrared regions, high performance liquid chromatography, microbiological turbidimetry, dissolution; and different people. I believe that this interaction is rich and my goal is always to strengthen the group with the teachings brought and lived in other laboratories with other ways of working, I believe that networking nowadays is differential and can bring great opportunities. In this way, we improve ourselves, become integrated people and contribute to world literature and benefit the community, the population, since we think in a multidimensional way focusing on the whole, the parts and, above all, the interaction between the parts of a system.