Rifaximin

Key points

• Rifaximin is a non-systemic antibiotic with broad-spectrum activity against gastrointestinal pathogens.
• It works by inhibiting bacterial RNA synthesis.
• Relief of symptoms usually begins within 1 to 3 days.

What rifaximin is used for

Rifaximin is used in hepatic encephalopathy, where its effect on gut bacteria lowers ammonia production, and in traveller’s diarrhoea. A course typically runs for 14 days.

How rifaximin works

The medicine binds to the beta-subunit of bacterial DNA-dependent RNA polymerase. That binding blocks RNA synthesis, which stops the bacteria from functioning and multiplying. Rifaximin also modifies the intestinal microbiota, and this change in the gut flora is what reduces ammonia production in hepatic encephalopathy.

Forms and strengths

MayChemist supplies Rifaximin as a film-coated tablet in 200 mg, 400 mg and 550 mg strengths. Pharmacy partners in India ship orders to Malaysia in discreet packaging.

Safety and side effects

Do not take rifaximin if you have had a hypersensitivity reaction to it, or if you have an intestinal obstruction. Liver function should be monitored while you take it, and caution is needed in severe hepatic impairment. Stop the medicine and seek medical advice if symptoms of colitis appear.

Minor effects include dizziness, headache, nausea and abdominal pain. Flatulence, defaecation urgency and raised liver enzymes are moderate effects. Clostridioides difficile-associated diarrhoea is a serious side effect and needs immediate medical attention.

Rifaximin interacts with ciclosporin. It is not recommended for children under 12 years. In pregnancy it is not recommended unless necessary, because clinical data are lacking. During breastfeeding, caution is advised: systemic absorption is low, but excretion into milk is possible.

Further reading

• Rifaximin
• Xifaxan - healthdirect
• Rifaximin: MedlinePlus Drug Information
• Rifaximin (oral route) - Mayo Clinic