Should Rifaximin be taken with food?

Rifaximin Can Be Taken With or Without Food

Rifaximin can be taken with or without food as stated in the FDA drug label, with no specific food requirements for administration. 1

Administration Guidelines for Rifaximin

• The FDA drug label for Xifaxan (rifaximin) explicitly states that "XIFAXAN can be taken with or without food" 1
• Rifaximin is a poorly absorbed antibiotic (<0.4% absorption) that acts locally in the gastrointestinal tract, which explains why food intake does not significantly impact its efficacy 2
• The medication maintains high concentration levels in the intestine because it is not absorbed, and it remains in an active form until it is excreted 3

Dosing Recommendations by Indication

• For travelers' diarrhea: One 200 mg tablet 3 times a day for 3 days 1
• For hepatic encephalopathy: One 550 mg tablet 2 times a day 1
• For irritable bowel syndrome with diarrhea (IBS-D): One 550 mg tablet 3 times a day for 14 days 1

Pharmacological Considerations

• Rifaximin is a rifamycin derivative that inhibits bacterial RNA synthesis by binding to bacterial DNA-dependent RNA polymerase 3
• It has broad antimicrobial activity against aerobic and anaerobic gram-positive and gram-negative bacteria 4
• After oral administration, fecal levels of rifaximin can exceed 8000 μg/g after 3 days of therapy, demonstrating its high local concentration in the gut 2

Clinical Implications

• Unlike some medications that require specific food timing for optimal absorption, rifaximin's minimal systemic absorption (<0.4%) means food intake has little impact on its therapeutic efficacy 2, 4
• This flexibility in administration (with or without food) can improve patient adherence to the medication regimen 5
• In clinical trials for hepatic encephalopathy and IBS-D, rifaximin demonstrated efficacy and safety profiles comparable to placebo, regardless of food intake 5

Special Considerations

• For patients with irritable bowel syndrome with diarrhea, the standard dose is 550 mg three times daily for 14 days, which can be taken with or without food 3, 1
• For hepatic encephalopathy management, rifaximin (400 mg three times daily or 550 mg twice daily) can be administered without food timing restrictions 3
• When used for travelers' diarrhea, rifaximin (400 mg twice daily) has shown comparable efficacy to ciprofloxacin regardless of food intake 6

Potential Drug Interactions

• Caution should be exercised when concomitant use of rifaximin and a P-glycoprotein inhibitor is needed, but this is not related to food intake 1
• Patients taking warfarin should have their INR and prothrombin time monitored, as dose adjustments may be needed to maintain target INR range 1