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Comparing Two Oral Doses of macitentan (10 mg vs 75 mg) in Healthy Participants for Pulmonary Arterial Hypertension

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What is this trial about?

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

The study focuses on Pulmonary Arterial Hypertension, a condition where the blood pressure in the arteries that carry blood from the heart to the lungs becomes abnormally high. The medication being examined is macitentan, a pill taken by mouth that is intended to help lower this pressure. The trial also uses inactive tablets, called placebos, so that neither the participants nor the researchers know which pill contains the active drug at any given time.

The purpose of the study is to compare how two different doses of macitentan (10 mg and 75 mg) affect the removal of endothelin-1 from the bloodstream in healthy volunteers. Participants will take one dose for a short period, then, after a break, will switch to the other dose, while the study remains double‑blind. During the visits, blood samples will be collected and the participants’ blood flow will be examined after gently warming the skin on the hand, a simple way to see how the blood vessels respond.

The researchers will look at changes in the level of endothelin-1, which is a protein that can cause blood vessels to narrow, and will assess overall endothelial function (how well the inner lining of the vessels works) and hemodynamics (the movement and pressure of blood). This information helps determine whether the higher dose works differently from the lower dose and contributes to the overall understanding of the drug’s safety and activity.

The research process

The trial runs in 7 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Baseline Assessments

    You will attend a baseline visit where health measurements, blood sampling, and other safety checks are performed to confirm eligibility for the study.

    These assessments establish the starting point for later comparisons of the study medication effects.

  2. Step 2

    First Treatment Period

    You will receive either macitentan 10 mg film‑coated tablets or a matching placebo tablet, depending on the random assignment.

    Take one tablet by mouth each day, at the same time each day, for the entire first treatment period as instructed by the study staff.

    The tablet contains 10 mg of the active substance macitentan (or no active substance if it is a placebo).

  3. Step 3

    Monitoring During First Period

    You will visit the study site regularly for safety checks, blood draws, and other measurements.

    These visits allow the study team to evaluate changes in blood levels of ET‑1 (endothelin‑1) and other health indicators while you are taking the study medication.

  4. Step 4

    Washout Phase

    After the first treatment period ends, you will stop taking any study medication for a washout period designed to let the drug leave your body.

    During this time you will not receive any tablets, but you may still attend scheduled safety visits.

  5. Step 5

    Second Treatment Period

    You will receive the alternate medication: if you previously took macitentan 10 mg, you will now receive macitentan 75 mg tablets; if you previously received a placebo, you will now receive the matching active tablet, or vice versa.

    Take one tablet by mouth each day, at the same time each day, for the entire second treatment period as instructed.

    The tablet contains 75 mg of the active substance macitentan (or no active substance if it is a placebo).

  6. Step 6

    Monitoring During Second Period

    You will continue to attend regular visits for safety monitoring, blood sampling, and assessment of ET‑1 clearance and other study measurements.

    These data are compared with the results from the first treatment period to evaluate the effect of the two dose levels.

  7. Step 7

    Final Study Visit

    At the end of the second treatment period you will undergo a final set of evaluations, including a physical exam and blood tests.

    After this visit the study is considered complete for you, and no further study medication is required.

Who can join the trial?

15 criteria

  • Be between 18 and 55 years old, inclusive.
  • Be a man or woman.
  • Be in good health based on a physical exam and medical history; any small issues must be judged not important by the doctor.
  • Have normal results from routine lab tests (blood chemistry, blood counts, urine); any abnormal results must be judged not important by the doctor.
  • Have blood pressure within the range of 100–145 mmHg systolic (SBP) and 50–90 mmHg diastolic (DBP), and a pulse rate of 45–90 beats per minute, measured after lying down for at least 5 minutes.
  • Have a normal resting heart test (12‑lead ECG) without serious problems; heart rate must be 45–90 beats per minute, PR interval ≤210 ms, and QTcF <450 ms for men or <460 ms for women.
  • Weigh at least 50 kg and have a body‑mass index (BMI) between 18.0 and 25.0 kg/m².
  • Sign an informed consent form (ICF) showing understanding of the study and willingness to participate.
  • Be able to communicate well with the study staff in the local language and follow the study requirements.
  • Agree to follow any lifestyle restrictions described in the study protocol.
  • Women must have a negative highly sensitive blood test for β‑hCG (a pregnancy hormone) at screening and a negative urine pregnancy test on Day 1.
  • Women must either be unable to become pregnant or, if they can, must use an acceptable birth‑control method and continue using it throughout the study and for at least 30 days after the last dose.
  • Women must agree not to donate eggs (ova) during the study and for at least 30 days after the last dose.
  • Men must agree to wear a condom for any activity that could allow semen to reach another person, and must not donate sperm for at least one sperm‑production cycle (about 90 days) after the last dose.
  • Contraceptive use must follow local regulations for participants in clinical studies.

Who cannot join the trial?

20 criteria

  • Any disease, surgery, or medical condition that could affect how the study drug is absorbed, spread, broken down, or removed from the body.
  • Low hemoglobin (≤11 g/dL) at screening – hemoglobin is the protein in red blood cells that carries oxygen.
  • Positive test for HIV‑1 or HIV‑2 at screening – HIV is a virus that weakens the immune system.
  • Positive test for hepatitis (hepatitis A IgM antibody, hepatitis B surface antigen, or hepatitis C antibody) at screening – hepatitis infections affect the liver.
  • Being an employee of the investigators or study site, or a family member of those employees.
  • History of drug or alcohol abuse within the past 3 years, or a positive drug/alcohol test at screening or on Day 1 – abuse is defined by DSM‑V criteria (a standard guide for mental health diagnoses).
  • Use of nicotine (smoking, nicotine patch, gum, or electronic cigarettes) within 3 months before screening, inability to stay nicotine‑free during the study, or a positive test for cotinine (a substance the body makes after using nicotine) at screening or on Day 1.
  • Donated blood or blood products, or lost more than 500 mL of blood, within 3 months before the first dose, or planning to donate blood during the study.
  • Unable to swallow whole pills with water – participants may not chew, split, dissolve, or crush the study medication.
  • Pregnant, breastfeeding, or planning to become pregnant while in the study or within 30 days after the last dose.
  • Planning to father a child while in the study or within 90 days after the last dose.
  • History of cancer (malignancy) diagnosed within the past 5 years, except for certain skin cancers (squamous or basal cell) and early‑stage cervical cancer that are considered cured.
  • Any condition that the investigator believes would make participation unsafe or would interfere with the study’s measurements.
  • Known allergy, hypersensitivity, or intolerance to macitentan (Opsumit®) or any of its inactive ingredients.
  • Major surgery requiring general anesthesia within 6 months before screening, not fully recovered from surgery, surgery planned during the study, or surgery planned within 4 weeks after the last dose.
  • Presence of orthostatic hypotension – a drop in blood pressure of more than 20 mmHg systolic or 10 mmHg diastolic after standing for 3 minutes compared with lying down.
  • Any contraindication (reason not to use) to macitentan according to its prescribing information.
  • Use of any prohibited medicines or therapies before the first dose of the study drug.
  • Received another investigational drug, vaccine, or invasive device within 30 days (or five half‑lives, whichever is longer) before the first dose, received a biological product within 3 months (or five half‑lives), or currently enrolled in another investigational study.
  • Liver enzyme levels (ALT or AST) higher than 1.5 times the upper limit of normal at screening – ALT and AST are enzymes that indicate liver health.
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Investigated drugs

  • Opsumit

    is an oral tablet that contains the active ingredient macitentan. Macitentan works by blocking a chemical called endothelin‑1, which can cause blood vessels to tighten. In this study, participants take Opsumit each day at a low dose to see how it changes the body’s ability to clear endothelin‑1, how well the blood vessels function, and how it affects overall blood flow and heart pressure.

  • JNJ 67896062

    is a code‑named oral tablet that also contains macitentan. It is the same type of medicine as Opsumit but is used in the study at a higher dose. The purpose of giving JNJ 67896062 is to compare the effects of a larger amount of macitentan with the lower amount, looking at changes in endothelin‑1 clearance, blood‑vessel health, and heart‑related measurements in healthy volunteers.

What is already known about the treatment

  • Opsumit 10 mg film‑coated tablets

    This medication is taken by mouth as a film‑coated tablet. It is an approved drug used to treat pulmonary arterial hypertension, a rare condition that raises blood pressure in the lungs. The tablet works by blocking endothelin receptors, which helps blood vessels relax and lowers pressure. It belongs to the class of endothelin receptor antagonists.

  • JNJ 67896062 37 mg film‑coated tablet

    This is an oral film‑coated tablet being studied in clinical trials and is not yet approved for general medical use. It contains macitentan and is investigated for the same lung‑pressure disease, pulmonary arterial hypertension. Like the approved version, it blocks endothelin receptors to improve blood flow in the lungs. It is classified as an endothelin receptor antagonist.

  • JNJ 67896062 75 mg film‑coated tablet

    This oral tablet is also an investigational form of macitentan, currently under study and not commercially available. It is intended for use in pulmonary arterial hypertension, the same rare lung‑vascular condition. The drug works by preventing endothelin from tightening blood vessels, thereby reducing pressure. It falls under the endothelin receptor antagonist drug class.

Investigated diseases

Pulmonary Arterial Hypertension - Pulmonary arterial hypertension is a condition where the arteries that carry blood from the heart to the lungs become narrowed, thickened, or stiff. This raises pressure in the pulmonary arteries and makes the right side of the heart work harder. Over time, the increased workload can cause the right ventricle to enlarge and become less efficient. Symptoms often start with shortness of breath during activity and may progress to fatigue and swelling in the legs. The disease typically advances gradually, with worsening exercise tolerance as the arterial changes continue.
Trial detailsLast updated 12 Oct 2026
Age18+ yearsPhasePhase ITrial ID2023-504643-13-00Estimated enrolment20 patientsSponsorActelion Pharmaceuticals Ltd.

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