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Study comparing tadalafil with ambrisentan versus tadalafil alone in newly diagnosed patients with pulmonary arterial hypertension who have cardiovascular conditions

Verified siteRegistered drugNo placebo
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What is this trial about?

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

This study focuses on patients with Pulmonary Arterial Hypertension, a condition where blood pressure in the arteries of the lungs is abnormally high. The study aims to compare two different treatment approaches: a combination therapy using two medications versus treatment with a single medication plus placebo. The medications being studied are ambrisentan and tadalafil, which are both taken by mouth in the form of tablets.

The research will examine which treatment strategy is more effective at controlling the disease after 6 months in newly diagnosed patients who also have heart and blood vessel-related health conditions. During the study, participants will be divided into two groups. One group will receive both ambrisentan and tadalafil, while the other group will receive tadalafil and a placebo. The treatment period will last approximately 175 days.

Throughout the study, various aspects of the participants' health will be monitored, including their ability to exercise, heart function, and overall well-being. The medications being tested are already approved for medical use, but they will be studied in a specific combination to determine if this approach provides better results for patients with additional cardiovascular health conditions.

The research process

The trial runs in 5 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Initial evaluation and medication start

    You will start taking either a combination of two medications or one real medication and one placebo:

    - Ambrisentan 5 mg tablet (or its placebo) taken by mouth once daily

    - Tadalafil taken by mouth once daily

  2. Step 2

    Regular monitoring visits

    Your health status will be monitored through several tests:

    - Walking test (6-minute walk distance)

    - Blood tests including specific markers for heart function

    - Heart and lung function tests

    - Quality of life questionnaires

    - Blood pressure and heart rate measurements

    - Weight monitoring

  3. Step 3

    6-month evaluation

    After 6 months of treatment, your condition will be evaluated to determine:

    - Changes in your ability to exercise

    - Changes in heart and lung function

    - Your overall response to the treatment

    - Any side effects you may have experienced

  4. Step 4

    Ongoing monitoring

    Throughout the study period, you will be monitored for:

    - Any changes in your symptoms

    - Side effects from the medications

    - Need for additional treatments

    - Overall health status

  5. Step 5

    Study completion

    The study is expected to run until October 2028

    Your participation will help evaluate the effectiveness of combination therapy versus single medication treatment for pulmonary arterial hypertension

    All health changes and medication effects will be documented throughout your participation

Who can join the trial?

16 criteria

  • Must be an adult (18 years or older)
  • Must be diagnosed with Pulmonary Arterial Hypertension (PAH) within the last 6 months
  • Must meet specific blood pressure measurements in the lungs:
    • Mean pulmonary artery pressure of 25 mmHg or higher
    • Pulmonary artery wedge pressure of 15 mmHg or less
    • Pulmonary vascular resistance of 3 Wood Units or higher
    • Must have never received treatment for PAH before
    • Must have PAH that is either:
      • Inherited
      • Without known cause
      • Related to drug use
      • Connected to tissue disease
      • Associated with HIV infection
      • Related to corrected heart defect (fixed more than 1 year ago)
      • Must have at least two of these health conditions:
        • High blood pressure
        • Diabetes (any type)
        • Obesity (body mass index of 30 or higher)
        • Heart disease (such as previous heart attack, heart procedures, blocked arteries, or stable chest pain)

Who cannot join the trial?

15 criteria

  • Age below 18 years or above 75 years
  • Previous treatment with any medications for pulmonary arterial hypertension (high blood pressure in the lungs)
  • Pregnancy or breastfeeding
  • Severe liver disease
  • Severe kidney disease requiring dialysis
  • History of heart attack or stroke in the past 6 months
  • Uncontrolled high blood pressure
  • Active bleeding disorders
  • Use of nitrate medications for chest pain
  • Known allergic reactions to tadalafil or ambrisentan
  • Participation in other clinical trials within the past 30 days
  • Life-threatening conditions requiring immediate treatment
  • Inability to provide informed consent
  • Substance abuse or addiction that could interfere with study participation
  • Mental health conditions that could affect compliance with study procedures
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Investigated drugs

  • Tadalafil

    is a medication that helps relax blood vessels and improves blood flow in the lungs. It belongs to a group of medicines called PDE5 inhibitors and is used to treat pulmonary arterial hypertension (high blood pressure in the lungs). It helps patients breathe more easily and improve their exercise capacity.

  • Ambrisentan

    is a medication that works by blocking the action of a natural substance in the body that causes blood vessels to narrow. It helps widen the blood vessels in the lungs, making it easier for the heart to pump blood through them. This medication is used to treat pulmonary arterial hypertension and helps improve the ability to exercise and slow down the worsening of symptoms.

What is already known about the treatment

  • Tadalafil

    An oral medication belonging to the phosphodiesterase type 5 (PDE5) inhibitor class, primarily used in the treatment of pulmonary arterial hypertension (PAH). The medication works by relaxing blood vessels in the lungs, which helps to reduce blood pressure in the pulmonary arteries and improve exercise capacity. It is taken in tablet form once daily, and its mechanism of action involves increasing levels of cyclic GMP in vascular smooth muscle cells, leading to vasodilation.

  • Ambrisentan

    An endothelin receptor antagonist administered orally in tablet form, specifically approved for treating pulmonary arterial hypertension (PAH). The medication works by blocking the effects of endothelin, a substance that causes blood vessels to narrow, thereby helping to improve blood flow and reduce blood pressure in the lungs. It is typically taken once daily and has been shown to improve exercise capacity and delay clinical worsening in PAH patients.

Investigated diseases

Pulmonary Arterial Hypertension - A rare condition where blood pressure in the arteries of the lungs becomes abnormally high. This happens when the tiny arteries in the lungs become narrow or blocked, making it harder for blood to flow through them. The heart must work harder to pump blood through these narrowed arteries, which causes increased pressure. Over time, the increased workload causes the heart's right ventricle to become larger and weaker. The condition typically develops gradually, with symptoms including shortness of breath during physical activity, fatigue, dizziness, and chest pain.
Trial detailsLast updated 2 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2023-509891-40-00Protocol codeAPHP230847Estimated enrolment186 patientsSponsorAssistance Publique Hopitaux De Paris

sourced from the EU Clinical Trials Register and site verification

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© 2026 Clinical Trials EU – European Clinical Trials Information Network

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On this site, “treatment” means an investigational medicine being studied in a clinical trial. Its safety and efficacy for the use being studied have not yet been confirmed, some participants may receive a placebo or a comparator medicine, and taking part does not guarantee any health benefit. The decision to take part is made by the doctor at the research site. This site is for information only and does not replace medical advice.

This service is not affiliated with the European Commission, the EMA, or the official CTIS system. Most information comes from publicly available international clinical-trial registries, supplemented by data from academic sites, national regulators and commercial sponsors. On this site, “treatment” and “therapy” mean a medicine being tested in a clinical trial. Its safety and effectiveness in the use being studied are not yet confirmed, some participants may receive a placebo or a comparator, and taking part does not guarantee a health benefit. The doctor at the research site decides who can take part. This site provides information, not medical advice. Certain content and visual elements on this website have been generated or enhanced using artificial intelligence (AI).