Dosing & Uses
Dosage Forms & Strengths
200 mg PO q8hr for 3 days
Maintenance of remission
550 mg PO q12hr
Irritable Bowel Syndrome
Indicated for irritable bowel syndrome with diarrhea (IBS-D) in adult men and women
550 mg PO q8hr for 14 days; recurrence of symptoms can be retreated with a 14 day treatment course, up to 2 times
Available in unit-dose package containing 42 tablets (ie, 2 week supply) for this indication
Dosage Forms & Strengths
<12 years: Safety and efficacy not established
≥12 years: 200 mg PO q8hr for 3 days, with or without food
Serious - Use Alternative
Significant - Monitor Closely
Rectal tenesmus (7%)
Abdominal pain (7%)
Defecation urgency (6%)
Frequency Not Defined
Hypersensitivity reactions (including allergic dermatitis)
Hypersensitivity to rifamycin antibiotics
Not effective in diarrhea complicated by fever, hematochezia, or diarrhea due to pathogens other than Escherichia coli
Not effective against traveler's diarrhea due to Campylobacter jejuni
Clostridium difficile-associated diarrhea has been reported
Efficacy against traveler's diarrhea due to Shigella spp and Salmonella spp not proven
Discontinue if symptoms worsen or persist >24-48 hr
Possibility of pseudomembranous colitis
Monitor patients with severe hepatic impairment for increased systemic exposure
Coadministration with P-gp inhibitors substantially increases systemic exposure to rifaximin; coadministration of cyclosporine with rifaximin resulted in 83-fold and 124-fold increases in rifaximin mean Cmax and AUC in healthy subjects
Pregnancy & Lactation
Pregnancy category: C
Lactation: Do not use if nursing or do not nurse
A:Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B:May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C:Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D:Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X:Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA:Information not available.
Mechanism of Action
Antimicrobial action is a result of binding to the beta-subunit of bacterial DNA-dependent RNA polymerase, resulting in inhibition of transcription
Hepatic encephalopathy: Inhibits growth of enteric ammonia-producing bacteria to indirectly reduce serum ammonia level
Irritable bowel syndrome with diarrhea: The exact mechanism of action for IBS-D is not known, but is thought to be related to changes in the bacterial content in the gastrointestinal tract and reduction of gas
Peak plasma time: 1 hr
Induces CYP3A4 in hepatocytes in vitro
Half-life: 2-5 hr
Excretion: Feces (>90%)
May take with or without food
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