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Pronunciation: rif-AX-i-min
Class: Anti-infective agent

Trade Names

- Tablets 200 mg
- Tablets 550 mg


Inhibits bacterial RNA synthesis.

Slideshow: Foodborne Illness: The Guest Nobody Invited



Systemic absorption is low. Mean C max 3.4 ng/mL; median T max is 0.8 h; mean AUC 12.3 ng•h/mL. Food delayed T max from 0.75 h to 1.5 h and increased AUC 2-fold.


Moderately bound to plasma proteins (67.5%).


Enzymes responsible for metabolizing rifaximin are unknown.


The half-life is 1.8 h. Excreted primarily in feces (97% of administered dose) and 0.32% in the urine.

Special Populations

Renal Function Impairment

Pharmacokinetics have not been studied.

Hepatic Function Impairment

The mean AUC was 2-fold higher in patients with Child-Pugh class C hepatic impairment than in patients with Child-Pugh class A impairment.

Indications and Usage

Treatment of traveler's diarrhea by noninvasive strains of Escherichia coli (200 mg); reduction in risk of overt hepatic encephalopathy (550 mg).

Unlabeled Uses

Irritable bowel syndrome, recurrent Clostridium difficile –associated diarrhea.


Hypersensitivity to any rifamycins or any component of product.

Dosage and Administration

Hepatic Encephalopathy

PO 550 mg 2 times daily.

Traveler's Diarrhea
Adults and Children 12 y of age and older

PO 200 mg 3 times daily for 3 days.

General Advice

May be taken with or without food.


Store tablets at 59° to 86°F.

Drug Interactions

None well documented.

Adverse Reactions


Dizziness (13%); fatigue (12%); headache (10%); depression (7%); amnesia, confusional state, disturbance in attention, hypoesthesia, memory impairment, tremor (2% to 5%); abnormal dreams, insomnia, malaise, migraine, syncope, weakness (less than 2%).


Pruritus (9%); rash (5%); clamminess, increased sweating, sunburn (less than 2%).


Nasopharyngitis (7%); ear pain, motion sickness, nasal passage irritation, pharyngitis, pharyngolaryngeal pain, rhinitis, rhinorrhea, tinnitus (less than 2%).


Nausea (14%); abdominal pain (9%); abdominal pain upper (6%); abdominal tenderness, anorexia, dry mouth, esophageal variceal bleed, lower abdominal pain, stomach discomfort (2% to 5%); abdominal distension, blood in stool, diarrhea, dry lips, dry throat, dysentery, fecal abnormality, gingival disorder, inguinal hernia, loss of taste (less than 2%).


Blood in urine, choluria, dysuria, hematuria, polyuria, proteinuria, urinary frequency (less than 2%).


Anemia (8%); lymphocytosis, monocytosis, neutropenia (less than 2%).


Anaphylaxis, angioneurotic edema, exfoliative dermatitis, flushing, pruritus, rash, urticaria (postmarketing).

Lab Tests

Increased AST (less than 2%).


Peripheral edema (15%); dehydration, hyperglycemia, hyperkalemia, hypoglycemia, hyponatremia, weight increase (2% to 5%); weight loss (less than 2%).


Muscle spasms (9%); arthralgia (6%); myalgia, pain in extremity (2% to 5%); neck pain (less than 2%).


Dyspnea (6%); epistaxis, pneumonia, rhinitis, upper respiratory tract infection (2% to 5%); respiratory tract infection (less than 2%).


Ascites (11%); pyrexia (6%); cellulitis, chest pain, contusion, fall, flu-like illness, generalized edema, hypotension, pain, procedural pain, vertigo (2% to 5%); hot flashes, pain (less than 2%).



Category C .




200 mg

Safety and efficacy not established in children younger than 12 y of age.

550 mg

Safety and efficacy not established in patients younger than 18 y of age.


Reactions have been reported, including anaphylaxis, angioneurotic edema, and exfoliative dermatitis.

Hepatic Function

Use with extreme caution in severe hepatic failure because of increased systemic exposure.

C. difficile –associated diarrhea

Consider in patients in whom diarrhea develops subsequent to treatment.


Not found to be effective in treating traveler's diarrhea caused by pathogens other than E. coli or in patients with diarrhea complicated by fever and/or blood in the stool.



None well documented.

Patient Information

  • Advise patients to notify health care provider if diarrhea persists more than 24 to 48 h or worsens. Advise the patient to seek medical care for fever and/or blood in the stool.
  • Advise patients to contact health care provider as soon as possible if diarrhea occurs after therapy, or if it does not improve or worsens during therapy.
  • Inform patients that rifaximin may be taken with or without food.
  • Counsel patients that antibacterial drugs, including rifaximin, should only be used to treat bacterial infections. Inform patients that although it is common to feel better early in the course of therapy, to take the medication exactly as directed.

Copyright © 2009 Wolters Kluwer Health.