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Study Comparing the Effectiveness and Safety of Macitentan 75 mg and 10 mg for Patients with Pulmonary Arterial Hypertension

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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 a condition known as Pulmonary Arterial Hypertension (PAH). PAH is a type of high blood pressure that affects the arteries in the lungs and the right side of the heart. The study is testing a medication called Macitentan, which is already used in a 10 mg dose, and comparing it to a higher dose of 75 mg. The purpose of the study is to see if the higher dose of Macitentan is more effective in delaying the time to the first serious health event related to PAH.

Participants in the study will be randomly assigned to receive either the 10 mg or 75 mg dose of Macitentan. Some participants may receive a placebo, which looks like the medication but does not contain the active ingredient. The study will be conducted in a way that neither the participants nor the researchers know who is receiving which treatment, to ensure unbiased results. After the initial phase, all participants will have the opportunity to receive the 75 mg dose of Macitentan in an open-label period, meaning everyone will know they are receiving the active medication.

The study will last for a period of up to 72 weeks, during which participants will be monitored for any changes in their condition and any side effects they may experience. The goal is to determine if the higher dose of Macitentan can better manage the symptoms of PAH and improve the quality of life for those affected by this condition. Participants will be required to visit the study site regularly for check-ups and assessments throughout the study period.

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

    Randomization

    Upon joining the study, participants are randomly assigned to one of two groups. One group receives macitentan 75 mg, and the other group receives macitentan 10 mg. This process is double-blind, meaning neither the participants nor the researchers know which dosage each participant receives.

  2. Step 2

    Double-blind treatment period

    Participants take their assigned dosage of macitentan orally once daily. This phase continues until a specific number of health events occur among participants, as determined by the study's design.

  3. Step 3

    Open-label treatment period

    After the double-blind period, all participants receive macitentan 75 mg. This phase allows researchers to gather additional data on the long-term effects of the higher dosage.

  4. Step 4

    Monitoring and assessments

    Throughout the study, participants undergo regular health assessments to monitor the effects of the medication. These assessments include physical exams, blood tests, and other evaluations to ensure safety and effectiveness.

  5. Step 5

    Completion

    The study concludes when the predetermined number of health events has been reached, and all data has been collected and analyzed. Participants may receive follow-up care as needed.

Who can join the trial?

12 criteria

  • Participants must be **18 years or older** or the legal age of consent in the area where the study is conducted.
  • **Female participants** who can have children must have a **negative pregnancy test** before starting the study.
  • Female participants must use a **highly effective method of birth control** during the study and for 30 days after the last dose of the study medication.
  • Participants must be **willing and able** to follow the lifestyle rules specified in the study.
  • Participants must have **symptomatic pulmonary arterial hypertension (PAH)** in WHO Functional Class II, III, or IV. This means they have symptoms that affect their daily activities.
  • Participants must **understand and agree** to the study's purpose and procedures by signing a consent form.
  • Participants must have a specific type of PAH, such as **idiopathic** (unknown cause), **heritable** (runs in families), **drug- or toxin-induced**, or related to other conditions like **connective tissue disease** or **HIV infection**.
  • Participants must have a **confirmed PAH diagnosis** through specific heart and lung tests done at rest before the study.
  • Participants with idiopathic, heritable, or drug/toxin-induced PAH must have a **negative vasoreactivity test** or a confirmed PAH diagnosis if already on PAH treatment for more than 3 months.
  • Participants must be able to **walk a distance** of at least 50 meters but not more than 440 meters during a walking test at the start of the study. If they can walk more than 440 meters, they must meet additional criteria.
  • Participants already on PAH treatments must have been on a **stable treatment plan** for at least 3 months before the study and follow specific guidelines regarding their current medications.
  • Participants must sign a separate consent form if they agree to provide **optional samples for biomarker research**. Not agreeing to this does not exclude them from the study.

Who cannot join the trial?

5 criteria

  • Patients who have a different condition than pulmonary arterial hypertension (a type of high blood pressure that affects the arteries in the lungs and the right side of the heart) cannot participate.
  • Patients who are not within the specified age range for the study cannot participate.
  • Patients who are part of a vulnerable population, which means they might need special protection or care, cannot participate.
  • Patients who are not able to follow the study procedures or take the study medication as required cannot participate.
  • Patients who have any other medical condition that might interfere with the study or its results cannot participate.
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Investigated drugs

Macitentan: This medication is used to treat pulmonary arterial hypertension (PAH), a condition where there is high blood pressure in the arteries that go from the heart to the lungs. The trial is comparing two different doses of macitentan to see which is more effective in delaying the worsening of the disease or preventing death. Macitentan works by relaxing and widening the blood vessels, which helps to lower blood pressure and improve blood flow.

What is already known about the treatment

Macitentan – This medication is administered orally in tablet form and is primarily used to treat pulmonary arterial hypertension (PAH). It is currently well-documented in medical literature and is undergoing clinical trials to compare the efficacy of different dosages. Macitentan works by blocking endothelin receptors, which helps to relax blood vessels and reduce blood pressure in the lungs. It is classified as an endothelin receptor antagonist.

Investigated diseases

Pulmonary arterial hypertension – This is a condition characterized by high blood pressure in the arteries that supply the lungs. It occurs when the small arteries in the lungs become narrowed or blocked, making it harder for blood to flow through them. As a result, the heart has to work harder to pump blood through these arteries, which can lead to heart strain and eventually heart failure. Symptoms often include shortness of breath, fatigue, dizziness, and swelling in the ankles or legs. Over time, the condition can progress, leading to more severe symptoms and complications. It is considered a rare disease and can significantly impact a person's quality of life.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2024-515669-32-00Protocol codeAC-055-315Estimated enrolment900 patientsSponsorActelion Pharmaceuticals Ltd.

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