II. Indications
- Irritable Bowel Syndrome
- Traveler's Diarrhea
- Hepatic Encephalopathy Prevention
- Clostridioides difficile Receurrence Prevention (not FDA approved)
III. Contraindications
- Dysentary (febrile, bloody Diarrhea)
- Rifamycin allergy (e.g. Rifampin)
- Severe liver Impairment (relative, risk of increased Rifaximin exposure)
IV. Mechanism
- Oral semisynthetic Antibiotic, derived from Rifamycin
- Activity primarily limited to the Gastrointestinal Tract (minimal absorption)
- Binds Bacterial DNA-dependent RNA Polymerase and inhibits Bacterial RNA synthesis and Bacterial growth
- Modifies gut microbiome to reduce Diarrhea
V. Dosing
-
Traveler's Diarrhea (adults or age >=12 years)
- Take 200 mg orally three times daily for 3 days
-
Hepatic Encephalopathy Prevention
- Take 550 mg orally twice daily
-
Irritable Bowel Syndrome
- Take 550 mg orally three times daily for 14 days
- May repeat 14 day course up to twice
-
Clostridioides difficile Receurrence Prevention (not FDA approved, for adults or age >=12 years)
- Take 400 mg orally three times daily for 20 days
VI. Adverse Effects
VII. Safety
- Pregnancy Category X in first trimester
- Unknown safety beyond first trimester
- Unknown Safety in Lactation
VIII. Pharmacokinetics
- Minimal absorption
- Excreted in stool
IX. Efficacy
-
Irritable Bowel Syndrome
- Improves Abdominal Pain, stool consistency, bloating (NNT 10)
- Relapse within 6 months in 50% of patients
X. Drug Interactions
-
Warfarin
- May decrease INR
-
P-Glycoprotein Inhibitors (e.g. Cyclosporine)
- Increase Rifaximin levels
XI. Resources
XII. References
- Hamilton (2020) Tarascon Pocket Pharmacopoeia
- (2021) Irritable Bowel Syndrome Drug Comparison, Presc Lett, #370305
- (2020) Med Lett Drugs Ther 62(1594): 41-58
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| xifaxan (on 1/1/2022 at Medicaid.Gov Survey of pharmacy drug pricing) | ||
| XIFAXAN 200 MG TABLET | $9.21 each | |
| XIFAXAN 550 MG TABLET | $47.68 each | |