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Rifaximin

Medically reviewed by Drugs.com. Last updated on Sep 5, 2020.

Pronunciation

(rif AX i min)

Dosage Forms

Excipient information presented when available (limited, particularly for generics); consult specific product labeling.

Tablet, Oral:

Xifaxan: 200 mg [contains edetate disodium]

Xifaxan: 550 mg

Brand Names: U.S.

  • Xifaxan

Pharmacologic Category

  • Rifamycin

Pharmacology

Rifaximin inhibits bacterial RNA synthesis by binding to bacterial DNA-dependent RNA polymerase.

Absorption

Oral:

Travelers' diarrhea: Low

Hepatic encephalopathy: Increased absorption in patients with Child-Pugh class C compared with patients with Child-Pugh class A

Metabolism

Extensive, mainly by CYP3A

Excretion

Feces (96.6% primarily as unchanged drug); urine (0.32%)

Time to Peak

Healthy subjects and patients with IBS without constipation: ~1 hour

Half-Life Elimination

Healthy subjects: 5.6 hours; IBS without constipation: 6 hours

Protein Binding

Healthy subjects: 67.5%; Hepatic impairment: 62%

Special Populations: Hepatic Function Impairment

The mean AUC in patients with hepatic impairment of Child-Pugh class A, B, and C was 10-, 14-, and 21-fold higher, respectively, compared with that of healthy subjects.

Use: Labeled Indications

Hepatic encephalopathy: Reduction in the risk of overt hepatic encephalopathy recurrence in adults.

Irritable bowel syndrome without constipation: Treatment of moderate to severe irritable bowel syndrome without constipation in adults.

Travelers' diarrhea: Treatment of travelers' diarrhea caused by noninvasive strains of Escherichia coli in adults and pediatric patients ≥12 years of age.

Limitations of use: Rifaximin should not be used in patients with diarrhea complicated by fever or blood in the stool or diarrhea caused by pathogens other than E. coli.

Off Label Uses

Clostridioides (formerly Clostridium) difficile infection (second or subsequent recurrence)

Data from a randomized, double-blind, placebo-controlled pilot study support the use of rifaximin to prevent recurrent diarrhea in patients with Clostridioides (formerly Clostridium) difficile infection [Garey 2011].

Based on the Infectious Diseases Society of America (IDSA) and Society for Healthcare Epidemiology of America (SHEA) guidelines for C. difficile infection, rifaximin, following a standard course of oral vancomycin therapy, is an adjunctive treatment option in patients with more than 1 recurrence of C. difficile infection.

Hepatic encephalopathy, treatment

Based on the American Association for the Study of Liver Diseases (AASLD) practice guideline for hepatic encephalopathy, rifaximin may be added to lactulose therapy for the treatment of overt hepatic encephalopathy.

Small intestinal bacterial overgrowth

Data from a limited number of patients studied suggest rifaximin may be beneficial for the treatment of small intestinal bacterial overgrowth (SIBO) [Boltin 2014], [Scarpellini 2007].

Based on the American College of Gastroenterology clinical guideline for SIBO, rifaximin may be used in symptomatic patients with SIBO to eradicate overgrowth and resolve symptoms [ACG [Pimentel 2020]].

Travelers’ diarrhea, prophylaxis

Data from a randomized, double-blind, placebo-controlled study support the use of rifaximin to prevent travelers’ diarrhea [DuPont 2005].

Based on the International Society of Travel Medicine guidelines for prevention and treatment of travelers’ diarrhea, rifaximin may be used to prevent travelers’ diarrhea.

Contraindications

Hypersensitivity to rifaximin, other rifamycin antibiotics, or any component of the formulation

Dosing: Adult

Note: The 200 mg tablet may not be available in some international markets; consult local product labeling for availability.

Clostridioides (formerly Clostridium) difficile infection (second or subsequent recurrence) (alternative regimen) (off-label use): Oral: 400 mg 3 times daily for 20 days; administer after a 10-day course of oral vancomycin (Garey 2011; IDSA/SHEA [McDonald 2018]; Johnson 2007).

Hepatic encephalopathy, treatment (off-label use) or chronic prevention of recurrence: Note: Use as an adjunct or alternative to nonabsorbable disaccharides (eg, lactulose) in patients intolerant of or with insufficient response to disaccharides (AASLD [Vilstrup 2014]; Ferenci 2020).

Oral: 400 mg 3 times daily or 550 mg twice daily (AASLD [Vilstrup 2014]; Ferenci 2020; Mohammad 2012; Puxeddu 1995). When used for treatment of an acute episode, may be given for 5 to 10 days (Mas 2003).

Irritable bowel syndrome, moderate to severe, without constipation (alternative agent): Note: Reserve for patients, particularly those with bloating, who have failed other therapies (Lembo 2016; Pimentel 2011; Wald 2019).

Oral: 550 mg 3 times daily for 14 days (Lembo 2016; Pimentel 2011; Wald 2019).

Small intestinal bacterial overgrowth (off-label use): Oral: 550 mg 3 times daily for 14 days (ACG [Pimentel 2020]; Pimentel 2019; Scarpellini 2007). For patients with methane-predominant bacterial overgrowth, some experts use rifaximin as part of an appropriate combination regimen (Pimentel 2019).

Travelers’ diarrhea:

Prophylaxis (off-label use): Note: Routine prophylaxis is not recommended. Reserve for select short-term travelers (eg, <2 weeks) at high risk of complications from diarrheal illness. Effectiveness for travelers to South and Southeast Asia may be reduced (Riddle 2017).

Oral: 200 mg 1 to 3 times daily for the duration of travel; optimal dose and duration not well established (DuPont 2005; Hu 2012; LaRocque 2019; Steffen 2015).

Treatment, moderate to severe (alternative agent): Note: Avoid in patients with fever or bloody diarrhea (Riddle 2017).

Oral: 200 mg 3 times daily for 3 days (Riddle 2017).

Dosage adjustment for concomitant therapy: Significant drug interactions exist, requiring dose/frequency adjustment or avoidance. Consult drug interactions database for more information.

Dosing: Geriatric

Refer to adult dosing.

Dosing: Pediatric

Note: The 200 mg tablet may not be available in some international markets; consult local product labeling for availability.

Clostridioides (formerly Clostridium) difficile infection (second or subsequent recurrence):

Children <12 years: Very limited data available: Oral: 15 to 30 mg/kg/day in divided doses 3 times daily for 20 days; usual adult dose: 400 mg/dose; administer after a 10-day course of oral vancomycin (Bradley 2019; Gawronska 2017; IDSA/SHEA [McDonald 2018]).

Children ≥12 years and Adolescents: Oral: 400 mg 3 times daily for 20 days; administer after a 10-day course of oral vancomycin (Garey 2011; IDSA/SHEA [McDonald 2018]).

Inflammatory bowel disease (IBD) (Crohn disease, ulcerative colitis): Limited data available: Children ≥8 years and Adolescents: Oral: 10 to 30 mg/kg/day in divided doses; maximum daily dose: 1,200 mg/day. Dosing based on a retrospective experience of 23 pediatric patients (age range: 8 to 21 years) with IBD flare (Crohn disease: n=12; ulcerative colitis: n=11); patients received rifaximin 400 to 1,200 mg/day (10 to 30 mg/kg/day); improvements in diarrhea and abdominal pain were reported within the first 4 weeks of therapy for the majority of patients (~74%), and within a week in some cases; higher total daily doses (1,200 mg/day vs 400 mg/day) were associated with better symptom control (Muniyappa 2009).

Small intestinal bacterial overgrowth (SIBO) (eg, associated with irritable bowel syndrome [IBS], short bowel syndrome, chronic abdominal pain): Limited data available; efficacy results variable.

Children 3 to <8 years: Oral: 200 mg 3 times daily for 7 to 14 days (Chandra 2018; Scarpellini 2013).

Children ≥8 years and Adolescents <18 years: Oral: 200 to 550 mg 3 times daily for 7 to 14 days (Chandra 2018; Collins 2011; Scarpellini 2013).

Adolescents ≥18 years: Oral: 550 mg 2 times daily.

Dosing based on expert recommendations and a prospective study of 50 pediatric patients with SIBO and IBS (age range: 3 to 15 years); results showed 7 days of therapy resulted in improved symptoms and a reduction in bacterial overgrowth based on lactulose breath test (LBT) results (Scarpellini 2013); however, a double-blind placebo-controlled trial in pediatric patients (n=75 including 49 who received rifaximin; age range: 8 to 18 years) with SIBO and chronic abdominal pain showed very low efficacy in normalizing LBT (20% response rate) and treating SIBO compared to placebo at a higher dose of 550 mg 3 times daily for 7 days (Collins 2011). Based on adult experience, some experts use rifaximin as part of an appropriate combination regimen in patients with methane-predominant bacterial overgrowth (Pimentel 2019). Note: While pediatric data is lacking, rifaximin has shown efficacy (as an add on with lactulose or as an alternative if patients intolerant to lactulose) in adults for treatment or chronic prevention of hepatic encephalopathy (AASLD [Vilstrup 2014]).

Travelers' diarrhea, treatment: Note: Avoid use in diarrhea with fever or blood in the stool; consider alternative therapy if symptoms persist or worsen after 24 to 48 hours of treatment.

Children 3 to 11 years: Limited data available: Oral: 100 mg 4 times daily for up to 5 days has been used in 38 children (age range: 3 to 8 years) to treat infectious diarrhea (Beseghi 1998; Frisari 1997).

Children ≥12 years and Adolescents: Oral: 200 mg 3 times daily for 3 days.

Dosage adjustment for concomitant therapy: Significant drug interactions exist, requiring dose/frequency adjustment or avoidance. Consult drug interactions database for more information.

Extemporaneously Prepared

A 20 mg/mL oral suspension may be made using tablets. Crush six 200 mg tablets and reduce to a fine powder. Add 30 mL of a 1:1 mixture of Ora-Sweet® and Ora-Plus® or a 1:1 mixture of Ora-Sweet® SF and Ora-Plus®; mix well while adding the vehicle in geometric proportions to almost 60 mL; transfer to a calibrated bottle, rinse mortar with vehicle, and add quantity of vehicle sufficient to make 60 mL. Label "shake well". Stable 60 days at room temperature.

Cober MP, Johnson CE, Lee J, et al, "Stability of Extemporaneously Prepared Rifaximin Oral Suspensions," Am J Health Syst Pharm, 2010, 67(4):287-89.20133533

Administration

Oral: Administer with or without food.

Storage

Store at 20°C to 25°C (68°F to 77°F); excursions permitted to 15°C to 30°C (59°F to 86°F).

Drug Interactions

Cholera Vaccine: Antibiotics may diminish the therapeutic effect of Cholera Vaccine. Management: Avoid cholera vaccine in patients receiving systemic antibiotics, and within 14 days following the use of oral or parenteral antibiotics. Avoid combination

Erdafitinib: May increase the serum concentration of P-glycoprotein/ABCB1 Substrates (High risk with Inhibitors). Monitor therapy

Lasmiditan: May increase the serum concentration of P-glycoprotein/ABCB1 Substrates (High risk with Inhibitors). Avoid combination

Lumacaftor and Ivacaftor: May increase the serum concentration of P-glycoprotein/ABCB1 Substrates (High risk with Inhibitors or Inducers). Lumacaftor and Ivacaftor may decrease the serum concentration of P-glycoprotein/ABCB1 Substrates (High risk with Inhibitors or Inducers). Monitor therapy

P-glycoprotein/ABCB1 Inhibitors: May increase the serum concentration of RifAXIMin. Monitor therapy

Sodium Picosulfate: Antibiotics may diminish the therapeutic effect of Sodium Picosulfate. Management: Consider using an alternative product for bowel cleansing prior to a colonoscopy in patients who have recently used or are concurrently using an antibiotic. Consider therapy modification

Typhoid Vaccine: Antibiotics may diminish the therapeutic effect of Typhoid Vaccine. Only the live attenuated Ty21a strain is affected. Management: Avoid use of live attenuated typhoid vaccine (Ty21a) in patients being treated with systemic antibacterial agents. Postpone vaccination until 3 days after cessation of antibiotics and avoid starting antibiotics within 3 days of last vaccine dose. Consider therapy modification

Adverse Reactions

The following adverse drug reactions and incidences are derived from product labeling unless otherwise specified.

Frequency of adverse events generally higher following treatment for hepatic encephalopathy (HE). Percentages are presented for HE unless otherwise stated.

>10%:

Cardiovascular: Peripheral edema (15%)

Central nervous system: Dizziness (13%), fatigue (12%)

Hepatic: Ascites (11%)

Gastrointestinal: Nausea (14%; irritable bowel syndrome with diarrhea 2% to 3%)

2% to 10%:

Central nervous system: Headache (travelers' diarrhea 10%), depression (7%)

Dermatological: Pruritus (9%), skin rash (5%)

Gastrointestinal: Abdominal pain (>2% to 9%), pseudomembranous colitis (<5%; travelers' diarrhea or irritable bowel syndrome with diarrhea <2%)

Hematologic & oncologic: Anemia (8%)

Hepatic: Increased serum ALT (irritable bowel syndrome with diarrhea 2%)

Neuromuscular & skeletal: Muscle spasm (9%), arthralgia (6%), increased creatine phosphokinase (<5%; travelers' diarrhea or irritable bowel syndrome with diarrhea <2%)

Respiratory: Nasopharyngitis (7%), dyspnea (6%), epistaxis (>2% to 5%)

Miscellaneous: Fever (6%)

All indications: <2%, postmarketing, and/or case reports: Anaphylaxis, angioedema, Clostridioides (formerly Clostridium) difficile-associated diarrhea, exfoliative dermatitis, flushing, hypersensitivity reaction, urticaria

Warnings/Precautions

Concerns related to adverse effects:

• Hypersensitivity: Hypersensitivity reactions (eg, exfoliative dermatitis, rash, urticaria, flushing, angioneurotic edema, pruritus, anaphylaxis) have occurred; these events have occurred as early as within 15 minutes of drug administration.

• Superinfection: Prolonged use may result in fungal or bacterial superinfection, including Clostridioides (formerly Clostridium) difficile-associated diarrhea (CDAD) and pseudomembranous colitis; CDAD has been observed >2 months postantibiotic treatment.

Disease-related concerns:

• Diarrhea: Appropriate use: Avoid use in diarrhea with fever and/or blood in the stool and in the treatment of diarrhea due to pathogens other than Escherichia coli, including Campylobacter jejuni, ShigellaI spp., and Salmonella spp. (efficacy has not been established). Consider alternative therapy if symptoms persist or worsen after 24 to 48 hours of treatment.

• Hepatic impairment: Efficacy for prevention of encephalopathy has not been established in patients with a Model for End-Stage Liver Disease (MELD) score >25; use caution in patients with severe hepatic impairment (Child-Pugh class C).

Dosage form specific issues:

• Propylene glycol: Some dosage forms may contain propylene glycol; large amounts are potentially toxic and have been associated hyperosmolality, lactic acidosis, seizures, and respiratory depression; use caution (AAP 1997; Zar 2007).

Other warnings/precautions:

• Appropriate use: Not for treatment of systemic infections; <1% is absorbed orally.

Monitoring Parameters

Hypersensitivity reactions, temperature, blood in stool, change in symptoms; monitor changes in mental status in hepatic encephalopathy

Pregnancy Considerations

Adverse events have been observed in some animal reproduction studies. Due to the limited oral absorption of rifaximin in patients with normal hepatic function, exposure to the fetus is expected to be low.

Patient Education

What is this drug used for?

• It is used to treat diarrhea.

• It is used to prevent brain problems caused by very bad liver disease.

• It is used to treat irritable bowel syndrome.

• It may be given to you for other reasons. Talk with the doctor.

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:

• Stuffy nose

• Sore throat

• Muscle spasm

• Joint pain

• Headache

• Dizziness

• Abdominal pain

• Nausea

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

• Swelling of arms or legs

• Abdominal swelling

• Severe loss of strength and energy

• Shortness of breath

• Depression

Clostridioides (formerly Clostridium) difficile-associated diarrhea like abdominal pain or cramps, severe diarrhea or watery stools, or bloody stools.

• Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.

Note: This is not a comprehensive list of all side effects. Talk to your doctor if you have questions.

Consumer Information Use and Disclaimer: This information should not be used to decide whether or not to take this medicine or any other medicine. Only the healthcare provider has the knowledge and training to decide which medicines are right for a specific patient. This information does not endorse any medicine as safe, effective, or approved for treating any patient or health condition. This is only a limited summary of general information about the medicine's uses from the patient education leaflet and is not intended to be comprehensive. This limited summary does NOT include all information available about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to this medicine. This information is not intended to provide medical advice, diagnosis or treatment and does not replace information you receive from the healthcare provider. For a more detailed summary of information about the risks and benefits of using this medicine, please speak with your healthcare provider and review the entire patient education leaflet.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.