What is the recommended dose and frequency of Rifaximin (Rifamycin derivative)?

From the Guidelines

Rifaximin should be prescribed at a dose of 550 mg taken orally three times daily for 14 days for the treatment of irritable bowel syndrome with diarrhea (IBS-D), and may be retreated up to two times with the same dosage regimen if symptoms recur. This recommendation is based on the most recent guidelines from the American Gastroenterological Association (AGA) [ 1 ]. The AGA suggests retreatment with rifaximin in patients with IBS-D who develop recurrent symptoms after an initial response [ 1 ]. Key points to consider when prescribing rifaximin include:

• Dosage: 550 mg three times daily for 14 days
• Retreatment: up to two times with the same dosage regimen if symptoms recur
• Administration: can be taken with or without food
• Mechanism of action: inhibits bacterial RNA synthesis, acting primarily in the gut
• Safety profile: favorable, with minimal drug interactions and common side effects including nausea, bloating, and headache [ 1 ].

From the FDA Drug Label

The oral contraceptive study utilized an open-label, crossover design in 28 healthy female subjects to determine if XIFAXAN 200 mg orally administered three times a day for 3 days (the dosing regimen for travelers’ diarrhea) altered the pharmacokinetics of a single dose of an oral contraceptive containing 0. 07 mg ethinyl estradiol and 0. 5 mg norgestimate. An open-label oral contraceptive study was conducted in 39 healthy female subjects to determine if 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 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.

The recommended dose and frequency of Rifaximin is:

• 200 mg orally taken three times a day for 3 days for travelers’ diarrhea 2
• 550 mg orally administered three times a day for 7 days in another study 2

From the Research

Rifaximin Dose and Frequency

• The optimal dose and frequency of rifaximin vary depending on the condition being treated 3, 4, 5, 6, 7.
• For the treatment of irritable bowel syndrome (IBS), rifaximin is typically administered at a dose of 550 mg twice daily 5.
• In the treatment of hepatic encephalopathy, rifaximin is usually given at a dose of 550 mg twice daily, either alone or in combination with lactulose 6.
• A study evaluating the dosing of rifaximin soluble solid dispersion tablets in adults with cirrhosis found that a dose of 40 mg once nightly may be effective in reducing hospitalizations 7.
• Another study found that rifaximin SSD IR 40 mg twice daily significantly reduced the median time to overt hepatic encephalopathy resolution compared to lactulose plus placebo 7.

Specific Conditions and Dosing

• For IBS, the evidence suggests that rifaximin 550 mg twice daily is effective in reducing global IBS symptoms and improving bloating, abdominal pain, and stool consistency 5.
• In the treatment of hepatic encephalopathy, rifaximin 550 mg twice daily has been shown to reduce the recurrence of episodes and improve health-related quality of life 6.
• For cirrhosis, the optimal dose and frequency of rifaximin are still being studied, but a dose of 40 mg once nightly may be effective in reducing hospitalizations 7.