What is rifaximin, and how does it work (mechanism of action)?
Rifaximin is a semi-synthetic antibiotic used for
treating traveler’s diarrhea and
hepatic encephalopathy. It is derived from
rifamycin, a naturally occurring chemical produced by a bacterium called
Streptomyces mediterranei. Rifaximin is active against
bacterial strains that cause traveler’s diarrhea, preventing growth of the
bacteria by preventing them from manufacturing proteins needed for their
replication and survival. By suppressing growth of the bacteria, rifaximin
reduces symptoms of traveler’s diarrhea. Hepatic encephalopathy is a serious
neurologic complication of advanced liver disease that affects the brain. It is
believed to be caused by the absorption of ammonia and other chemicals produced
by bacteria in the intestine. It is believed that rifaximin prevents and treats
hepatic encephalopathy by reducing the intestinal bacteria that produce ammonia.
The FDA approved rifaximin in May 2004.
What brand names are available for rifaximin?
Is rifaximin available as a generic drug?
Do I need a prescription for rifaximin?
What are the side effects of rifaximin?
Common side effects associated with rifaximin include:
- urge to defecate,
- abdominal pain,
- flatulence, and
- fluid retention (edema).
Many of these side effects are also symptoms of traveler’s diarrhea which rifaximin is used
for treating. Rifaximin also causes allergic reactions, rash, and itching. Like
other antibiotics rifaximin can alter the normal bacteria in the colon and
encourage overgrowth of some bacteria such as
Clostridium difficile which causes
inflammation of the colon (pseudomembranous colitis). Patients who develop signs
of pseudomembranous colitis after starting rifaximin (diarrhea, fever, abdominal
pain, and possibly shock,) should contact their physician immediately.
Pancreatitis is inflammation of an organ in the abdomen called the pancreas.
What is the dosage for rifaximin?
The recommended dose for traveler’s diarrhea is 200 mg 3 times daily
for 3 days and the recommended dose for hepatic encephalopathy is 550 mg twice
daily. Rifaximin may be administered with or without meals.
Which drugs or supplements interact with rifaximin?
Rifaximin does not interact with
oral contraceptives and
does not significantly interact with midazolam. Rifaximin has a low risk of drug
interactions because it is poorly absorbed into the blood stream, and it does
not significantly affect liver enzymes that break down most drugs.
Is rifaximin safe to take if I’m pregnant or breastfeeding?
The safety of rifaximin in
pregnant women has not been adequately
It is not known whether rifaximin is excreted in
What else should I know about rifaximin?
What preparations of rifaximin are available?
Tablets: 200 and 550 mg
How should I keep rifaximin stored?
Rifaximin should be stored at room temperature at 15 C – 30 C (59 F – 86 F).