Rifaximin

Rifaximin, a bactericidal oral broad-spectrum antibiotic, is a semi-synthetic derivative of rifamycin. Rifaximin is practically not absorbed (< 1%) and is therefore only effective in the intestinal lumen. Furthermore, rifaximin is excreted almost completely unchanged with the stool. A broad germ spectrum, the lack of systemic side effects and an almost non-existent development of resistance make rifaximin an important therapeutic option for intestinal bacterial infections (Cuomo R et al.2017).

In Germany, rifaximin is approved for the treatment of travel diarrhea in adults caused by non-invasive enteropathogenic bacteria (such as Escherichia coli) (travel diarrhea = diarrhea acquired in a Mediterranean, subtropical or tropical country in travelers). Since 2013, rifaximin has also been approved in Germany for the treatment and prophylaxis of hepatic encephalopathy (Kang SH et al. 2017). In other countries there are approvals for the bacterial overgrowth syndrome (Gatta L et al. 2017).

Rifaximin has a bactericidal effect. The antibiotic irreversibly binds to the beta-subunit of the prokaryotic DNA-dependent RNA polymerase, thereby blocking the enzyme's binding to the DNA and thus initiating chain formation.

The active ingredient rifaximin has a broad antimicrobial activity spectrum against most Gram-positive and -negative, aerobic and anaerobic bacteria, covering most bacteria causing intestinal infections such as: Staphylococcus aureus; Streptococcus pyogenes; Enterococcus faecalis; Enterococcus faecium; Bacillus cereus; Clostridium difficile; Clostridium spp.; Peptococcus spp.; Peptostreptococcus spp.; Escherichia coli; (including enteroaggregative and enterotoxigenic E. coli); Salmonella spp.; Shigella spp.; Yersinia enterocolitica; Proteus spp.; Pseudomonas aeruginosa; Vibrio cholerae; Bacteroides fragilis; Bacteroides spp.; Microaerophil ; Campylobacter jejuni; Helicobacter pylori.

In a smaller study, efficacy of the antibiotic was found in rosacea (3x 400mg/day for 10 days); however, the efficacy in this indication has been questioned by other authors (Weinstock LB 2011)

Adults: 2-4 times/day 200 mg p.o. Max. Daily dose 800 mg.

Rifaximin has a favorable tolerability profile, which can be derived from its minimal systemic availability. The frequency is at placebo level in studies.

Rarer are gastrointestinal NW: flatulence, abdominal pain, nausea. It is difficult to distinguish them from the symptoms of the underlying disease to be treated.

Integument: Rare drug exanthema, urticaria.

Other: Rarely headache, dizziness, fatigue, urge to urinate, loss of appetite, menstrual disorders, increased liver values.

Rifaximin is not to be used in patients with clinical signs of invasive enteritis; furthermore, in cases of hypersensitivity to the active substance. No experience is available for the treatment of children.

Colidimin (A), Xifaxane (CH, D), Rifacol (I)

The drug has been available in Germany since 2008.

1. Cuomo R et al(2017) Rifaximin and diverticular disease: Position paper of the Italian Society of Gastroenterology (SIGE). Dig Liver Dis 49:595-603.
2. Gatta L et al (2017) Systematic review with meta-analysis: rifaximin is effective and safe for the treatment of small intestine bacterial overgrowth. Aliment Pharmacol Ther 45:604-616.
3. Kang SH et al (2017) Rifaximin treatment is associated with reduced risk of cirrhotic complications and prolonged overall survival in patients experiencing hepatic encephalopathy. Aliment Pharmacol Ther 46:845-855.https://www.ncbi.nlm.nih.gov/pubmed/28836723W
4. Vine LB (2013). Rosacea in Crohn's Disease: Effect of Rifaximin. J Clin Gastroenterol 45:295-296.