Xifaxan

Common Uses

Xifaxan is primarily prescribed for conditions affecting the gastrointestinal tract. Unlike many other antibiotics, it is poorly absorbed into the bloodstream, which allows it to work directly within the gut to target specific bacteria.

Irritable Bowel Syndrome with Diarrhea (IBS-D)

Xifaxan is approved for use in adults to treat irritable bowel syndrome when diarrhea is a primary symptom. It helps manage symptoms such as abdominal pain and loose stools by altering the bacteria in the digestive tract.

Traveler's Diarrhea

This medication is used to treat traveler's diarrhea caused by non-invasive strains of Escherichia coli (E. coli) in adults and children 12 years of age and older. It is important to note that it is not effective against diarrhea caused by viruses or infections that involve fever or bloody stools.

Hepatic Encephalopathy

Xifaxan is used to reduce the risk of recurring episodes of overt hepatic encephalopathy in adults with chronic liver disease. This condition occurs when the liver cannot properly filter toxins from the blood, leading to a buildup that affects brain function. The medication helps by reducing the growth of bacteria that produce these toxins in the intestines.

Targeted Action in the Gut

Xifaxan belongs to a class of medications known as rifamycin antibiotics. Unlike many other antibiotics that travel through the bloodstream to reach different parts of the body, Xifaxan is poorly absorbed by the stomach and intestines. This allows the medication to remain concentrated in the digestive tract, where it can act directly on the bacteria causing symptoms.

Mechanism of Action

The medication works by binding to an enzyme in bacteria called RNA polymerase. By blocking this enzyme, Xifaxan prevents the bacteria from making the proteins they need to survive and multiply. This helps to:

• Reduce harmful bacteria: In conditions like traveler's diarrhea, it stops the infection from spreading.
• Lower ammonia levels: In people with hepatic encephalopathy, it kills the bacteria that produce ammonia. High ammonia levels can lead to brain dysfunction when the liver is unable to filter toxins properly.
• Manage IBS symptoms: For irritable bowel syndrome with diarrhea (IBS-D), it is thought to reset the balance of bacteria in the gut, which can reduce bloating and improve stool consistency.

Because Xifaxan stays in the gut, it is less likely to cause side effects in other parts of the body compared to systemic antibiotics.

Common Side Effects

Many people using Xifaxan do not experience significant side effects. When they do occur, common symptoms may include:

• Nausea or stomach pain
• Dizziness or headache
• Feeling tired or fatigued
• Swelling in the hands, feet, or lower legs
• Gas (flatulence)
• An urgent need to have a bowel movement

Serious Side Effects

Contact a healthcare provider immediately if you experience any of the following serious side effects:

• Severe diarrhea: Watery or bloody stools, which may occur during treatment or several months after stopping the medication. This could indicate a serious intestinal infection known as Clostridioides difficile-associated diarrhea.
• Liver-related issues: Yellowing of the skin or eyes (jaundice) or a significant buildup of fluid in the abdomen.
• Allergic reactions: Symptoms such as hives, skin rash, itching, difficulty breathing, or swelling of the face, lips, tongue, or throat.
• Fever: Unexplained or persistent high temperature.

This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.

Allergic Reactions

Xifaxan is contraindicated in patients with a known hypersensitivity to rifaximin, any of the rifamycin antimicrobial agents, or any components of the product. Allergic reactions may include skin rash, itching, or more severe symptoms.

Clostridioides difficile-Associated Diarrhea

Like most antibacterial drugs, Xifaxan can alter the normal flora of the colon, which may lead to an overgrowth of Clostridioides difficile. This can cause diarrhea ranging in severity from mild to fatal colitis. If diarrhea occurs during or after treatment, medical evaluation is necessary.

Severe Liver Impairment

In patients with severe hepatic impairment (Child-Pugh Class C), there is an increase in systemic exposure to the drug. While the drug primarily stays in the gut, caution is advised when treating patients with advanced liver disease.

Limitations of Use

Xifaxan is not effective for diarrhea complicated by fever or bloody stools, or diarrhea caused by pathogens other than Escherichia coli, such as Campylobacter jejuni. If symptoms worsen or do not improve within 24 to 48 hours, alternative treatments may be needed.

Development of Drug-Resistant Bacteria

Prescribing Xifaxan in the absence of a proven or strongly suspected bacterial infection is unlikely to provide benefit and increases the risk of developing drug-resistant bacteria.

Pregnancy

Data regarding the use of Xifaxan in pregnant women is limited. In animal studies, high doses of the medication were associated with developmental issues in the offspring. However, it is not yet known if these effects occur in humans at standard doses. Healthcare providers typically only prescribe Xifaxan during pregnancy if the clinical need is clear and other options are not suitable.

Breastfeeding

It is currently unknown if Xifaxan passes into human breast milk. Because the medication is poorly absorbed by the body and primarily stays within the digestive tract, the amount expected to reach a nursing infant is likely low. Nevertheless, the potential effects on a breastfed child are not fully understood. Individuals who are breastfeeding should discuss the risks and benefits with their doctor to determine the safest course of action.

Dosage Forms

Xifaxan is currently available in the following form:

• Oral tablet

This medication is intended for oral administration and can be taken with or without food.

FDA Approval History

Xifaxan (rifaximin) was first approved by the U.S. Food and Drug Administration (FDA) in May 2004. It is a non-systemic antibiotic, meaning it acts primarily within the gastrointestinal tract with minimal absorption into the bloodstream.

Approved Indications

• Travelers' Diarrhea: Approved in 2004 for the treatment of travelers' diarrhea caused by noninvasive strains of Escherichia coli in patients 12 years of age and older.
• Hepatic Encephalopathy: Approved in 2010 to reduce the risk of recurrence of overt hepatic encephalopathy in adults.
• Irritable Bowel Syndrome with Diarrhea (IBS-D): Approved in 2015 for the treatment of IBS-D in adult patients.

Regulatory Status

Xifaxan is a prescription-only medication. It is not approved for the treatment of diarrhea complicated by fever or blood in the stool, nor is it indicated for diarrhea caused by pathogens other than E. coli. There are currently no boxed warnings or Risk Evaluation and Mitigation Strategies (REMS) associated with this drug.

Insurance Coverage

Xifaxan is a brand-name medication, and its cost can be high without insurance. Most commercial insurance plans and Medicare Part D provide coverage, but they often require prior authorization. This process requires your healthcare provider to confirm that the medication is medically necessary before the insurance company will cover the cost.

Financial Assistance Programs

There are several ways to potentially reduce the out-of-pocket cost of Xifaxan:

• Manufacturer Savings Cards: Patients with commercial insurance may be eligible for copay cards that reduce monthly costs.
• Patient Assistance Programs: For those who are uninsured or underinsured, the manufacturer may offer programs to provide the medication at a lower cost or for free, based on financial need and eligibility.
• Foundation Support: Some independent charitable foundations provide grants to help patients with specific conditions cover their medication copays.

Generic Availability

While generic rifaximin is available, it may only be approved for specific conditions, such as traveler's diarrhea. For other conditions like irritable bowel syndrome with diarrhea (IBS-D) or hepatic encephalopathy, the brand-name Xifaxan is typically prescribed, which can influence insurance reimbursement and total out-of-pocket expenses.