Dosage guidance:
Dosage form information: The 200 mg tablet may not be available in some international markets; consult local product labeling for availability.
Clostridioides 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 (Ref).
Children ≥12 years and Adolescents: Oral: 400 mg 3 times daily for 20 days; administer after a 10-day course of oral vancomycin (Ref).
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 (Ref).
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 (Ref).
Children ≥8 years and Adolescents: Oral: 200 to 550 mg 3 times daily for 7 to 14 days (Ref).
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 (Ref); 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 (Ref).
Travelers' diarrhea, treatment: Note: Avoid use in diarrhea with fever or blood in the stool or diarrhea caused by pathogens other than E. coli; 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 (Ref).
Children ≥12 years and Adolescents: Oral: 200 mg 3 times daily for 3 days (Ref).
Dosage adjustment for concomitant therapy: Significant drug interactions exist, requiring dose/frequency adjustment or avoidance. Consult drug interactions database for more information.
There are no dosage adjustments provided in the manufacturer's labeling (has not been studied).
Children ≥12 years and Adolescents: Oral: No dosage adjustment necessary. Use with caution in patients with severe impairment as systemic exposure is increased and pharmacokinetic parameters are highly variable.
(For additional information see "Rifaximin: Drug information")
Dosage guidance:
Dosage form information: The 200 mg tablet may not be available in some international markets; consult local product labeling for availability.
Clostridioides difficile infection (second or subsequent recurrence) (alternative regimen) (off-label use):
Note: Rifaximin resistance may be a concern; some experts avoid in patients who have previously received rifamycins, and others do not routinely recommend this regimen (Ref).
Oral: 400 mg 3 times daily for 20 days; administer after a 10-day course of oral vancomycin (Ref).
Hepatic encephalopathy, treatment (off-label use) or prevention: Note: Use as an adjunct or alternative to nonabsorbable disaccharides (eg, lactulose) in patients intolerant of or with insufficient response to disaccharides (Ref).
Oral: 550 mg twice daily or 400 mg 3 times daily (Ref). When used for treatment of an acute episode, continue therapy for at least 3 months (Ref).
Pouchitis (post ileal pouch-anal anastomosis), acute refractory disease (off-label use): Oral: 550 mg to 1 g every 12 hours in combination with ciprofloxacin for 28 days (Ref).
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 (Ref).
Oral: 200 mg 1 to 3 times daily for the duration of travel; optimal dose and duration not well established (Ref).
Treatment, moderate to severe (alternative agent): Note: Avoid in patients with fever or bloody diarrhea. Most cases are self-limited and may not warrant antimicrobial therapy (Ref). Some experts reserve antimicrobial therapy for certain high-risk travelers (eg, those with an immunocompromising condition) (Ref).
Oral: 200 mg 3 times daily for 3 days (Ref); consider alternative therapy if symptoms persist or worsen after 24 to 48 hours of treatment (Ref).
Dosage adjustment for concomitant therapy: Significant drug interactions exist, requiring dose/frequency adjustment or avoidance. Consult drug interactions database for more information.
The renal dosing recommendations are based upon the best available evidence and clinical expertise. Senior Editorial Team: Bruce Mueller, PharmD, FCCP, FASN, FNKF; Jason Roberts, PhD, BPharm (Hons), B App Sc, FSHP, FISAC; Michael Heung, MD, MS.
Altered kidney function: Mild to severe impairment: No dosage adjustment necessary (systemic absorption limited) (Ref).
Hemodialysis, intermittent (thrice weekly): Unlikely to be dialyzed: No supplemental dose or dosage adjustment necessary (systemic absorption limited) (Ref).
Peritoneal dialysis: Unlikely to be dialyzed: No dosage adjustment necessary (systemic absorption limited) (Ref).
CRRT: No dosage adjustment necessary (systemic absorption limited) (Ref).
PIRRT (eg, sustained, low-efficiency diafiltration): No dosage adjustment necessary (systemic absorption limited) (Ref).
No dosage adjustment necessary. Use with caution in severe impairment (Child-Pugh class C); however, systemic absorption is limited and pharmacokinetic parameters are highly variable.
Although rifaximin is used to treat the pathogens associated with travelers' diarrhea, Clostridioides difficile-associated infection or to reduce bacterial overgrowth in the setting of various disease states, it is ineffective against invasive pathogens (eg, Campylobacter jejuni, Shigella spp, and Salmonella spp) that cause infectious diarrhea (Ref).
Mechanism: Non–dose-related; failure of therapy. Rifaximin is a nonabsorbable antibiotic, and pathogens that invade the tissues will not have contact with an antimicrobial agent that does not penetrate the tissues (Ref).
Onset: Rapid; inadequate improvement in diarrhea symptoms within 3 days of treatment, specifically in the setting of tissue invasive bacterial species (Ref).
Risk factors:
• Fever associated with diarrhea (Ref)
• Blood in stool (Ref)
• Tissue invasive bacterial species (Campylobacter jejuni, Shigella spp, and Salmonella spp) (Ref)
Rifaximin-associated superinfections, including Clostridioides difficile-associated and Candida spp infections, may occur with the use of nonabsorbable antibiotics in certain at-risk patients (Ref). Clostridioides difficile colitis has been reported in patients on rifaximin therapy for Crohn disease (non-cirrhotics) (Ref) or for hepatic encephalopathy (cirrhotics) (Ref). Although the incidence is low and similar studies have shown no increased risk of C. difficile infections with rifaximin use (Ref), this has raised concern for potential risk of development of antimicrobial resistance with prolonged rifaximin use or repeated courses of treatment (Ref). In another study in recipients of allogeneic hematopoietic stem cell transplantation, rifaximin prophylaxis for acute graft-versus-host disease post-transplant was linked to an increased risk of micafungin‑resistant Candida spp infections, including invasive candidiasis (Ref). Rifaximin use appears not to be a risk factor and may be protective against infections when used preoperatively in liver transplant recipients and in patients with cirrhosis (Ref).
Mechanism: Dose- and time-related; related to cumulative exposure and impact on intestinal microbiota diversity leading to selection of opportunistic (eg, Candida), more virulent, or resistant pathogens (Ref).
Risk factors:
• Duration of therapy, prolonged (Ref)
• Concurrent or recent systemic antibiotic therapy (Ref)
• Concurrent or recent hospitalization (Ref)
• Advanced age (Ref)
• Immunocompromised (Ref)
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 in adults unless otherwise indicated.
>10%:
Cardiovascular: Peripheral edema (15%)
Gastrointestinal: Nausea (14%; patients with irritable bowel syndrome with diarrhea: 3%)
Hepatic: Ascites (11%)
Nervous system: Dizziness (13%), fatigue (12%)
1% to 10%:
Dermatologic: Pruritus (9%), skin rash (5%)
Gastrointestinal: Abdominal pain (9%; upper abdominal pain: 6%), Clostridioides difficile colitis (<5%)
Hematologic & oncologic: Anemia (8%)
Nervous system: Depression (7%), headache (patients with travelers' diarrhea: 10%)
Neuromuscular & skeletal: Arthralgia (6%), increased creatine phosphokinase in blood specimen (<5%), muscle spasm (9%), myalgia (<5%)
Respiratory: Dyspnea (6%), nasopharyngitis (7%)
Miscellaneous: Fever (6%)
Postmarketing (all indications):
Dermatologic: Stevens-Johnson syndrome (Fritz 2014), toxic epidermal necrolysis (Fritz 2014; Patel 2013)
Gastrointestinal: Clostridioides difficile-associated diarrhea
Hematologic & oncologic: Neutropenia (Hynicka 2012)
Hypersensitivity: Anaphylaxis, angioedema, hypersensitivity reaction (immediate and delayed) (Moya 2021)
Hypersensitivity to rifaximin, other rifamycin antibiotics, or any component of the formulation
Disease-related concerns:
• 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.
Excipient information presented when available (limited, particularly for generics); consult specific product labeling.
Tablet, Oral:
Xifaxan: 200 mg [contains edetate (edta) disodium]
Xifaxan: 550 mg
No
Tablets (Xifaxan Oral)
200 mg (per each): $12.71
550 mg (per each): $65.34
Disclaimer: A representative AWP (Average Wholesale Price) price or price range is provided as reference price only. A range is provided when more than one manufacturer's AWP price is available and uses the low and high price reported by the manufacturers to determine the range. The pricing data should be used for benchmarking purposes only, and as such should not be used alone to set or adjudicate any prices for reimbursement or purchasing functions or considered to be an exact price for a single product and/or manufacturer. Medi-Span expressly disclaims all warranties of any kind or nature, whether express or implied, and assumes no liability with respect to accuracy of price or price range data published in its solutions. In no event shall Medi-Span be liable for special, indirect, incidental, or consequential damages arising from use of price or price range data. Pricing data is updated monthly.
Excipient information presented when available (limited, particularly for generics); consult specific product labeling.
Tablet, Oral:
Zaxine: 550 mg
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.
Oral: Administer with or without food.
Oral: Administer with or without food.
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).
Treatment of travelers' diarrhea caused by noninvasive strains of Escherichia coli (FDA approved in ages ≥12 years and adults); reduction in the risk of overt hepatic encephalopathy recurrence (FDA approved in ages ≥18 years and adults); treatment of moderate to severe irritable bowel syndrome without constipation (FDA approved in adults); has also been used in inflammatory bowel disease, small intestinal bacteria overgrowth, and treatment of second or recurrent episodes of Clostridioides difficile infection.
RifAXIMin may be confused with fidaxomicin, rifAMPin.
Substrate of CYP3A4 (minor), OATP1A2/SLCO1A2, OATP1B1/1B3 (SLCO1B1/1B3), P-glycoprotein/ABCB1 (major); Note: Assignment of Major/Minor substrate status based on clinically relevant drug interaction potential; Inhibits OATP1A2/SLCO1A2
Note: Interacting drugs may not be individually listed below if they are part of a group interaction (eg, individual drugs within “CYP3A4 Inducers [Strong]” are NOT listed). For a complete list of drug interactions by individual drug name and detailed management recommendations, use the drug interactions program by clicking on the “Launch drug interactions program” link above.
Note: Interacting drugs may not be individually listed below if they are part of a group interaction (eg, individual drugs within “CYP3A4 Inducers [Strong]” are NOT listed). For a complete list of drug interactions by individual drug name and detailed management recommendations, use the drug interactions program
Bacillus clausii: Antibiotics may diminish the therapeutic effect of Bacillus clausii. Management: Bacillus clausii should be taken in between antibiotic doses during concomitant therapy. Risk D: Consider therapy modification
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. Risk X: Avoid combination
Fecal Microbiota (Live) (Oral): May diminish the therapeutic effect of Antibiotics. Risk X: Avoid combination
Fecal Microbiota (Live) (Rectal): Antibiotics may diminish the therapeutic effect of Fecal Microbiota (Live) (Rectal). Risk X: Avoid combination
Immune Checkpoint Inhibitors (Anti-PD-1, -PD-L1, and -CTLA4 Therapies): Antibiotics may diminish the therapeutic effect of Immune Checkpoint Inhibitors (Anti-PD-1, -PD-L1, and -CTLA4 Therapies). Risk C: Monitor therapy
Lonafarnib: May increase the serum concentration of P-glycoprotein/ABCB1 Substrates (High risk with Inhibitors). Risk C: Monitor therapy
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). Risk C: Monitor therapy
Mycophenolate: Antibiotics may decrease serum concentrations of the active metabolite(s) of Mycophenolate. Specifically, concentrations of mycophenolic acid (MPA) may be reduced. Risk C: Monitor therapy
P-glycoprotein/ABCB1 Inhibitors: May increase the serum concentration of RifAXIMin. Risk C: 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. Risk D: 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. Risk D: Consider therapy modification
Warfarin: RifAXIMin may diminish the anticoagulant effect of Warfarin. Risk C: Monitor therapy
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.
Temperature, blood in stool, change in symptoms; monitor changes in mental status in hepatic encephalopathy
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
Protein binding: Healthy subjects: 67.5%; Hepatic impairment: 62%
Metabolism: Extensive, mainly by CYP3A
Half-life elimination: Healthy subjects: 5.6 hours; IBS without constipation: 6 hours
Time to peak: Healthy subjects and patients with IBS without constipation: ~1 hour
Excretion: Feces (96.6%; primarily as unchanged drug); urine (0.32%)
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.
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