Formulary
Rifaximin: Indications, Dosing, Side Effects and Interactions
Rifaximin is a rifamycin that is poorly absorbed from the gastro-intestinal tract, and, therefore, should not be used to treat systemic infections.
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Rifaximin: Indications, Dosing, Side Effects and Interactions
Rifaximin is a rifamycin that is poorly absorbed from the gastro-intestinal tract, and, therefore, should not be used to treat systemic infections.
Drug action
Rifaximin is a rifamycin that is poorly absorbed from the gastro-intestinal tract, and, therefore, should not be used to treat systemic infections.
Indications and dose
**Travellers' diarrhoea that is not associated with fever, bloody diarrhoea, blood or leucocytes in the stool, or 8 or more unformed stools in the previous 24 hours**
- **Adult** (By Mouth): 200 mg every 8 hours for 3 days.
**Reduction in recurrence of hepatic encephalopathy**
- **Adult** (By Mouth): 550 mg twice daily.
Contraindications
Intestinal obstruction
Side effects
Common or very common Arthralgia; ascites; constipation; depression; dizziness; dyspnoea; gastrointestinal discomfort; gastrointestinal disorders; headaches; muscle complaints; nausea; oedema; skin reactions; vomiting Uncommon Anaemia; anxiety; appetite decreased; asthenia; balance impaired; concentration impaired; confusion; cough; diplopia; drowsiness; dry lips; dry mouth; dry throat; ear pain; fall; haematuria; hot flush; hyperhidrosis; hyperkalaemia; increased risk of infection; lymphocytosis; memory loss; muscle weakness; nasal complaints; neutropenia; oropharyngeal pain; pain; palpitations; polymenorrhoea; respiratory disorders; seizure; sensation abnormal; sleep disorders; sunburn; taste altered; urinary disorders; urine abnormalities; vertigo Rare or very rare Hypertension; hypotension Frequency not known Angioedema; syncope; thrombocytopenia; urine discolouration
Interactions
**Severe interactions:**
- In healthy subjects, clinical drug interaction studies demonstrated that rifaximin did not significantly affect the pharmacokinetics of CYP3A4 substrates, however, in hepatic impaired patients it...
**Other interactions (9):**
- There is no experience regarding administration of rifaximin to subjects who are taking another rifamycin antibacterial agent to treat a systemic bacterial infection.
- In vitro data show that rifaximin did not inhibit the major cytochrome P-450 (CYP) drug metabolizing enzymes (CYPs1A2, 2A6, 2B6, 2C8, 2C9, 2C19, 2D6, 2E1, and 3A4).
- In in vitro induction studies, rifaximin did not induce CYP1A2 and CYP 2B6 but was a weak inducer of CYP3A4.
- Both decreases and increases in international normalized ratio have been reported in patients maintained on warfarin and prescribed rifaximin.
- If co-administration is necessary, the international normalized ratio should be carefully monitored with the addition or withdrawal of rifaximin.
- Adjustments in the dose of oral anticoagulants may be necessary.
Pregnancy
Manufacturer advises avoid-toxicity in animal studies.
Breast feeding
Unlikely to be present in milk in significant amounts, but manufacturer advises avoid.
Hepatic impairment
When used for Hepatic encephalopathy: Manufacturer advises caution in severe impairment (risk of increased exposure).
Medicinal forms
Suspension,Tablet,Suspension
Clinical governance
**Author:** MedNext Clinical Team. **Clinical reviewer:** Dr Shameer Deen, MBBS, MS, MRCS. **Sources:** BNF, Indian Pharmacopoeia, CIMS India. **Correction:** Report errors at support@mednext.academy.
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