What is the recommended dosage of Rifaximin (Rifaximine) for various conditions?

From the Guidelines

Rifaximin dosage varies by condition, with the most recent and highest quality study recommending 550 mg three times daily for 14 days for Irritable Bowel Syndrome with Diarrhea (IBS-D) 1. For traveler's diarrhea in adults and children over 12, the standard dose is 200 mg three times daily for 3 days, as supported by guidelines for the prevention and treatment of travelers' diarrhea 1. Some key points to consider when prescribing rifaximin include:

• The medication works by inhibiting bacterial RNA synthesis, reducing intestinal bacterial load without significant systemic absorption, which minimizes side effects.
• Dosage adjustments may be needed for pediatric patients, with children under 12 requiring weight-based dosing determined by a physician.
• Rifaximin may interact with certain drugs, particularly warfarin and other antibiotics, so patients should inform their healthcare provider about all medications they're taking.
• The full course of rifaximin should be completed even if symptoms improve, and the medication can be taken with or without food as directed. Some specific conditions and their recommended rifaximin dosages are:
• Hepatic encephalopathy prevention: 550 mg twice daily for adults.
• IBS-D: 550 mg three times daily for 14 days, with possible retreatment for recurrence.
• Small intestinal bacterial overgrowth (SIBO): 550 mg three times daily for 14 days.

From the FDA Drug Label

The efficacy of XIFAXAN given as 200 mg orally taken three times a day for 3 days was evaluated in 2 randomized, multi‑center, double-blind, placebo-controlled studies in adult subjects with travelers’ diarrhea.

XIFAXAN 550 mg orally administered three times a day for 7 days altered the pharmacokinetics of a single dose of an oral contraceptive containing 0. 025 mg of ethinyl estradiol (EE) and 0. 25 mg norgestimate (NGM).

The recommended dosage of Rifaximin for various conditions is:

• Travelers’ Diarrhea: 200 mg orally taken three times a day for 3 days.
• Hepatic Encephalopathy (HE): 550 mg twice daily.
• Irritable Bowel Syndrome with Diarrhea (IBS-D): 550 mg three times a day for 14 days 2.

Note: The exact dosage for IBS-D is not explicitly mentioned in the provided text, but it is mentioned as 1,650 mg per day, which can be inferred as 550 mg three times a day. However, this information is not directly provided in the given text.

From the Research

Rifaximin Dosage

The recommended dosage of Rifaximin varies depending on the condition being treated.

• For hepatic encephalopathy, the dosage is typically 550 mg twice daily 3, 4.
• For travelers' diarrhea, the dosage is 600-1200 mg per day, divided into three doses 5.
• For other conditions, such as infectious diarrhea and diverticular disease, the optimal dosage has not been established, but 400-1200 mg per day has been used in some studies 6, 7.

Dosage Forms and Administration

Rifaximin is available in oral form and is typically administered with food to minimize gastrointestinal side effects.

• The medication should be taken as directed, with the entire dose taken at one time 6, 7.
• For patients with hepatic encephalopathy, rifaximin can be taken for an extended period to prevent recurrence 4.

Special Considerations

• The dosage of rifaximin may need to be adjusted in patients with renal impairment or other underlying medical conditions 6, 7.
• Rifaximin is generally well-tolerated, but patients should be monitored for signs of adverse effects, such as gastrointestinal symptoms or allergic reactions 3, 4, 5.