Therapeutic Effects and Mechanisms of Action of Rifaximin in Gastrointestinal Diseases  Herbert L. DuPont, MD, MACP  Mayo Clinic Proceedings  Volume 90, Issue 8, Pages 1116-1124 (August 2015) DOI: 10.1016/j.mayocp.2015.04.016 Copyright © 2015 Mayo Foundation for Medical Education and Research Terms and Conditions

Figure 1 Chemical structure of rifaximin (C43H51N3O11). Reprinted from Xifaxan (rifaximin) tablets [package insert],1 with permission from Salix Pharmaceuticals, Ltd. Mayo Clinic Proceedings 2015 90, 1116-1124DOI: (10.1016/j.mayocp.2015.04.016) Copyright © 2015 Mayo Foundation for Medical Education and Research Terms and Conditions

Figure 2 In an animal model, treatment with rifaximin for 10 days and subsequent assessment 30 days posttreatment indicated a decrease in bacterial counts as measured by qPCR, but a long-term effect was restricted to the duodenum. qPCR = quantitative polymerase chain reaction. ∗P=.08. From Dig Dis Sci,45 with permission. Mayo Clinic Proceedings 2015 90, 1116-1124DOI: (10.1016/j.mayocp.2015.04.016) Copyright © 2015 Mayo Foundation for Medical Education and Research Terms and Conditions

Figure 3 In an in vitro model, rifaximin treatment of HEp-2 (laryngeal) cells decreased EAEC bacterial adhesion (A) and rifaximin treatment of A549 (lung) cells after incubation with Bacillus anthracis decreased bacterial internalization (B). EAEC = enteroaggregative Escherichia coli. ∗P<.002. From Antimicrob Agents Chemother,44 with permission. Mayo Clinic Proceedings 2015 90, 1116-1124DOI: (10.1016/j.mayocp.2015.04.016) Copyright © 2015 Mayo Foundation for Medical Education and Research Terms and Conditions

Figure 4 Proposed mechanisms of action of rifaximin as a gut microenvironment modulator with cytoprotection properties and effects on various gastrointestinal conditions. HE = hepatic encephalopathy; IBS-D = diarrhea-predominant irritable bowel syndrome; TD = travelers’ diarrhea. Mayo Clinic Proceedings 2015 90, 1116-1124DOI: (10.1016/j.mayocp.2015.04.016) Copyright © 2015 Mayo Foundation for Medical Education and Research Terms and Conditions