Products
Rifaximin is commercially available in the form of film-coated tablets (Xifaxan). It was approved in many countries in 2015. In many countries, it was available earlier. Rifaximin was first released in Italy in the 1980s.
Structure and properties
Rifaximin (C43H51N3O11, Mr = 785.9 g/mol) is a semisynthetic pyridoimidazole derivative of rifamycin. It exists as a red-orange, crystalline, hygroscopic powder that is practically insoluble in water.
Effects
Rifaximin (ATC A07AA11) has antibacterial properties against Gram-positive and Gram-negative aerobic and anaerobic pathogens. The effects are based on inhibition of bacterial RNA synthesis by binding to the beta subunit of the enzyme DNA-dependent RNA polymerase in bacteria. Rifaximin is poorly absorbed (< 0.4%) and therefore is primarily effective locally in the intestine. In the indication of hepatic encephalopathy, inhibition of bacteria that produce ammonia is of importance.
Indications
To reduce the recurrence of episodes of manifest hepatic encephalopathy in patients ≥18 years of age with hepatic cirrhosis. In many countries, rifaximin is also approved for the treatment of traveler’s diarrhea caused by noninvasive enteropathogenic bacteria. Caution: in many countries, rifaximin has not yet been approved for this indication.
Dosage
According to the SmPC. Tablets are taken twice daily for the indication hepatic encephalopathy, regardless of meals.
Contraindications
- Hypersensitivity
- Intestinal obstruction
For complete precautions, see the drug label.
Interactions
Rifaximin is a weak inducer of CYP3A4 and a substrate of P-glycoprotein.
Adverse effects
The most common possible adverse effects include:
- Depression
- Dizziness
- Headache
- Dyspnea
- Gastrointestinal complaints
- Skin rash, itching
- Muscle cramps, joint pain
- Peripheral edema
