Rifapentine

Active Tuberculosis Treatment

Rifapentine is used to treat active pulmonary tuberculosis, which is a bacterial infection that primarily affects the lungs. When used for active TB, this medication must be taken in combination with other antituberculosis drugs. Using multiple medications together is necessary to ensure the infection is fully cleared and to help prevent the bacteria from becoming resistant to antibiotics.

Latent Tuberculosis Prevention

This medication is also prescribed for the treatment of latent tuberculosis infection. People with latent TB have the bacteria in their bodies but do not feel sick and cannot spread the infection to others. Rifapentine is used in these cases to prevent the latent infection from progressing into active, symptomatic disease.

Typical Use Cases

• It is generally used in adults and children who are at least 12 years of age.
• It is specifically effective against Mycobacterium tuberculosis bacteria.
• Because it is an antibiotic, it only treats bacterial infections and is not effective against viral infections such as the common cold or the flu.

Mechanism of Action

Rifapentine belongs to a group of medicines called rifamycins. It works by targeting and killing the bacteria responsible for tuberculosis (TB). It does this by blocking a specific enzyme known as DNA-dependent RNA polymerase.

Bacteria use this enzyme to translate their genetic code into proteins. By interfering with this process, rifapentine prevents the bacteria from:

• Creating essential proteins needed for survival.
• Multiplying and spreading the infection.
• Maintaining their cellular structure.

This medication is considered bactericidal, meaning it actively kills the bacteria rather than just slowing their growth. It is specifically effective against Mycobacterium tuberculosis, the primary cause of TB.

Because rifapentine targets bacterial processes, it is not effective against viruses, such as those that cause the common cold or the flu. It is typically used in combination with other medications to ensure all bacteria are eliminated and to prevent the bacteria from becoming resistant to treatment.

Common Side Effects

• Nausea or vomiting
• Diarrhea
• Headache
• Dizziness
• Joint pain
• Skin rash or itching
• Red-orange discoloration of urine, sweat, saliva, or tears (this is a harmless effect of the medication)

Serious Side Effects

Contact your healthcare provider immediately if you experience any of the following:

• Signs of liver problems, such as yellowing of the skin or eyes (jaundice), dark urine, loss of appetite, or pain in the upper right stomach area.
• Signs of low blood cell counts, including fever, chills, sore throat, unusual bruising, or extreme fatigue.
• Severe or persistent diarrhea, which may be watery or bloody.
• Severe allergic reactions, such as swelling of the face, lips, or throat, hives, or difficulty breathing.
• Flu-like symptoms, including muscle aches and shivering.

Liver Toxicity

Rifapentine has been associated with liver inflammation (hepatitis). Healthcare providers typically monitor liver function tests before and during treatment, especially in people with pre-existing liver disease or those who consume alcohol. Symptoms that may indicate liver problems include unexplained nausea, vomiting, dark urine, or yellowing of the skin and eyes.

Drug Interactions

This medication is a strong inducer of certain liver enzymes, which means it can cause the body to process other medicines more quickly. This may make other drugs less effective. Notable interactions include:

• Hormonal Contraceptives: Rifapentine can make birth control pills, patches, or implants less effective. Alternative non-hormonal methods are often recommended during treatment.
• Other Medications: It may interact with blood thinners, certain heart medications, and medicines used to treat HIV or organ transplant rejection.

Hypersensitivity and Skin Reactions

Serious allergic reactions, including anaphylaxis and a condition known as DRESS (Drug Reaction with Eosinophilia and Systemic Symptoms), have been reported. These reactions can be life-threatening and may involve fever, rash, and organ inflammation.

Body Fluid Discoloration

Rifapentine may cause a reddish-orange discoloration of urine, sweat, saliva, tears, and feces. This effect is generally harmless, but it can permanently stain soft contact lenses.

Diarrhea and Colitis

Like many antibiotics, rifapentine can change the natural bacteria in the gut, potentially leading to Clostridioides difficile-associated diarrhea. This can range from mild diarrhea to severe or fatal colitis.

Nitrosamine Impurities

The FDA has identified trace amounts of a nitrosamine impurity in some rifapentine products. While nitrosamines may increase the risk of cancer with long-term exposure, the FDA generally recommends that patients continue taking their medication as prescribed, as the risk of untreated tuberculosis is typically much higher than the risk from the impurity.

Pregnancy

There is limited information regarding the safety of rifapentine use in pregnant women. Animal studies have shown that high doses of the medication may cause harm to a developing fetus. Because of these findings, healthcare providers typically only prescribe rifapentine during pregnancy if the benefits to the mother outweigh the potential risks to the baby.

If you are pregnant or planning to become pregnant, discuss the risks and benefits of this treatment with your doctor. It is also important to note that rifapentine can interfere with hormonal birth control, such as birth control pills, patches, or implants. To prevent pregnancy while taking this medication, a non-hormonal form of contraception (such as condoms or a diaphragm) should be used.

Breastfeeding

It is not currently known whether rifapentine passes into human breast milk or if it could affect a nursing infant. Because many drugs are excreted in human milk, caution is advised. You should consult with your healthcare provider to decide whether to continue breastfeeding or stop taking the medication, considering the importance of the drug to your health.

Available Forms

Rifapentine is available in the following form:

• Oral Tablet: This medication is taken by mouth, usually with food.

The tablets are film-coated. This medication is often prescribed in combination with other drugs as part of a specific treatment regimen.

FDA Approval and Indications

Rifapentine is approved by the U.S. Food and Drug Administration (FDA) for use in combination with other antituberculosis drugs. It is indicated for the treatment of active pulmonary tuberculosis caused by Mycobacterium tuberculosis and for latent tuberculosis infection in individuals at high risk of progression to active disease.

Regulatory Safety Monitoring

The FDA has monitored rifapentine products for the presence of nitrosamine impurities, specifically 1-cyclopentyl-4-nitrosopiperazine (CPNP). While nitrosamines are considered potential carcinogens, the FDA has allowed the continued distribution of rifapentine with levels of CPNP above the acceptable intake limit to ensure the drug remains available for patients. This decision was made because the health risks of untreated tuberculosis are significantly higher than the potential risk from the impurity levels found in the medication.

There are currently no boxed warnings or Risk Evaluation and Mitigation Strategies (REMS) specifically required for rifapentine by the FDA.

Weight and Appetite Changes

Rifapentine is an antibiotic used to treat tuberculosis and is not intended for weight management. However, clinical studies have noted that some patients may experience a loss of appetite or a decrease in body weight while taking this medication.

Loss of Appetite

A loss of appetite, also referred to as anorexia in medical literature, is a known side effect of rifapentine. While this may lead to minor weight changes, it is important to monitor how much weight is lost during treatment.

Potential for Liver Issues

In some instances, a sudden or persistent loss of appetite and subsequent weight loss can be a sign of serious side effects, such as liver problems (hepatotoxicity). You should contact your healthcare provider immediately if you experience a loss of appetite along with any of the following symptoms:

• Nausea or vomiting
• Pain in the upper right part of the stomach
• Yellowing of the skin or the whites of the eyes
• Dark-colored urine
• Unusual tiredness or weakness

Your doctor may monitor your liver function through blood tests during your treatment. It is important to continue taking the medication as prescribed unless your doctor tells you to stop, as completing the full course is necessary to treat the infection.