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Study on High-Dose Rifampicin Safety for Adults with Complex Tuberculosis Using Isoniazid, Pyrazinamide, and Ethambutol Combination

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What is this trial about?

A plain-language summary of the goals, design and what participants do

This clinical trial is focused on studying the safety of using high doses of rifampicin for treating adults with difficult-to-treat tuberculosis (TB). Tuberculosis is an infectious disease that primarily affects the lungs but can also impact other parts of the body, known as extrapulmonary TB. The study will involve the use of Rifampicin 150 mg Capsules, Rifampicin 300 mg Capsules, and a combination medication called RIMSTAR®, which includes isoniazid, pyrazinamide, rifampicin, and ethambutol hydrochloride. These medications are taken orally, meaning they are swallowed.

The purpose of the study is to evaluate the safety of a higher dose of rifampicin, specifically 35 mg per kilogram of body weight per day, when used alongside standard doses of the other medications for eight weeks. The study will monitor participants for any severe side effects, which are referred to as severe adverse events, and compare these findings to historical data from patients who received a lower dose of rifampicin. The trial aims to understand if the higher dose is safe for patients with both pulmonary and extrapulmonary drug-susceptible TB, especially those who are considered difficult to treat due to various health conditions.

Participants in the study will receive either the high-dose rifampicin treatment or a standard treatment, which may include a placebo. The study will last for eight weeks, during which time participants will be closely monitored for any side effects and the effectiveness of the treatment. The trial will also assess how quickly the TB bacteria in the lungs are cleared, as well as any changes in the participants' quality of life and the costs associated with TB treatment. The study is expected to conclude by September 2026.

The research process

The trial runs in 4 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Initial assessment

    Upon joining the study, an initial assessment is conducted to confirm eligibility. This includes confirming a diagnosis of tuberculosis (TB) through tests such as a positive smear, Xpert MTB/RIF test, or M. tuberculosis culture.

    Female participants of childbearing age must undergo a pregnancy test to ensure a negative result before starting the trial.

  2. Step 2

    Medication administration

    Participants receive a high dose of rifampicin at 35 mg per kilogram of body weight per day. This is supplemented with standard doses of isoniazid, pyrazinamide, and ethambutol.

    The medications are administered orally in the form of capsules or film-coated tablets. The treatment duration is 8 weeks.

  3. Step 3

    Monitoring and evaluation

    Throughout the 8-week treatment period, participants are monitored for any severe adverse events, which are defined as grade 3 or higher according to the Common Terminology Criteria for Adverse Events (CTCAE).

    Regular assessments are conducted to evaluate the efficacy of the treatment, including the time it takes for sputum culture to convert from positive to negative.

  4. Step 4

    Completion of treatment

    At the end of the 8-week treatment period, the primary endpoint is assessed, which is the proportion of participants experiencing severe adverse events.

    Secondary endpoints include the proportion of participants with a favorable outcome, tolerability of the treatment, and changes in quality of life.

Who can join the trial?

12 criteria

  • Participants must have confirmed or probable **pulmonary** (lungs) or **extrapulmonary** (outside the lungs) **DS-TB** (drug-sensitive tuberculosis).
  • Participants must provide **informed consent**, which means they agree to join the study after understanding all the details.
  • Participants must have a positive test for tuberculosis, which can be a **positive smear**, **positive Xpert MTB/RIF test**, or **positive M. tuberculosis culture** for confirmed cases. For probable cases, a **histological study** (tissue examination) showing **necrotizing granulomas** (a type of tissue damage) or a **liquid biochemistry** test (fluid test) suggesting TB, along with symptoms similar to TB, is required.
  • Female participants who can have children must have a **negative pregnancy test** at the start of the study.
  • Participants must be **60 years or older**, or **18 years or older** with any of the following conditions:
    • **Body mass index (BMI)** of 18.5 or less, which indicates low body weight.
    • **HIV infection** (Human Immunodeficiency Virus).
    • **Diabetes Mellitus**, a condition where blood sugar levels are too high.
    • **Hepatitis C virus (HCV) infection**, shown by a positive HCV test.
    • **Hepatitis B virus (HBV) infection**, shown by a positive HBV test.
    • Daily **alcohol intake** of 2 or more units (1 unit is about a small glass of beer, cider, wine, or a shot of whisky).
    • **Chronic liver disease** from any cause, such as metabolic, toxic, or autoimmune reasons.
    • **Central Nervous System TB involvement**, meaning TB affecting the brain or spinal cord.

Who cannot join the trial?

4 criteria

  • Individuals who are not adults cannot participate. This means only people who are 18 years or older can join.
  • People who are not diagnosed with **tuberculosis** cannot take part. Tuberculosis is a disease that mainly affects the lungs but can also affect other parts of the body.
  • Participants who are not part of the difficult-to-treat subgroups of tuberculosis are excluded. This refers to specific groups of patients who have a harder time responding to standard treatments.
  • Individuals who are part of a vulnerable population are not eligible. Vulnerable populations include groups who might be at a higher risk of harm or exploitation.
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Investigated drugs

  • Rifampicin

    is an antibiotic used to treat tuberculosis. In this trial, it is being tested at a higher dose than usual to see if it is safe for patients with difficult-to-treat tuberculosis. The goal is to find out if the higher dose causes any serious side effects.

  • Isoniazid

    is another antibiotic that is commonly used to treat tuberculosis. It works by killing the bacteria that cause the disease. In this trial, it is given at the standard dose to help treat the infection.

  • Pyrazinamide

    is an antibiotic used in combination with other medications to treat tuberculosis. It helps to kill the bacteria and is part of the standard treatment regimen in this trial.

  • Ethambutol

    is an antibiotic that is used to treat tuberculosis. It works by stopping the growth of the bacteria. In this trial, it is used at the standard dose as part of the treatment plan.

What is already known about the treatment

Rifampicin – Rifampicin is administered orally in the form of tablets or capsules. It is currently being studied in clinical trials to assess its safety at high doses for treating complex drug-susceptible tuberculosis, both pulmonary and extrapulmonary. The main therapeutic use of rifampicin is to treat tuberculosis, often in combination with other medications. It works by inhibiting the bacterial RNA polymerase enzyme, which is essential for the bacteria to synthesize RNA and proteins, ultimately leading to bacterial death. Rifampicin is classified as an antibiotic, specifically a rifamycin derivative.

Investigated diseases

Tuberculosis – Tuberculosis is an infectious disease caused by the bacterium Mycobacterium tuberculosis. It primarily affects the lungs, leading to pulmonary tuberculosis, but can also impact other parts of the body, known as extrapulmonary tuberculosis. The disease spreads through the air when an infected person coughs or sneezes. Symptoms often include a persistent cough, chest pain, and coughing up blood, along with fever, night sweats, and weight loss. If untreated, the bacteria can multiply and cause significant damage to the lungs and other organs. The progression of the disease can vary, with some individuals experiencing a latent form where the bacteria remain inactive and cause no symptoms.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IITrial ID2024-519983-42-00Protocol codeRIAltaEstimated enrolment135 patientsSponsorFundacio Hospital Universitari Vall D’Hebron Institut De Recerca

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