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Efficacy and Safety of Sodium Valproate Added to Standard Therapy in Patients with Stable Pulmonary Arterial Hypertension – Phase 2b Randomized Study

Investigational
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What is this trial about?

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

The study looks at people with Pulmonary Arterial Hypertension, a condition where the blood vessels that carry blood from the heart to the lungs become narrowed, causing the heart to work harder. The medication being tested is called CS1, given as an oral modified‑release capsule, and it is added to the usual medicines that patients already take. The purpose of the study is to see whether CS1 can lower the pressure that the right side of the heart has to pump against, measured as pulmonary vascular resistance (PVR).

Participants who are already stable on their regular treatment will be randomly assigned to receive either CS1 or a placebo capsule that looks the same, without knowing which they get. The study lasts about a year, with visits every few weeks to check safety and how the heart and lungs are working. Simple tests include a six‑minute walk test (6MWD) to see how far a person can walk, a blood test for a heart‑stress marker (NT-proBNP), and non‑invasive heart imaging (an ultrasound called ECHO) to look at heart function. At the end of the study, the researchers will compare the changes in these measurements between the CS1 group and the placebo group to decide if the drug is helpful and safe.

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 Assessment and Randomization

    You will attend a baseline visit where your health status, including measurements of pulmonary arterial hypertension, will be recorded.

    Blood tests, an electrocardiogram (ECG), and a physical examination will be performed to ensure you are stable on your current therapy.

    Based on the information collected, you will be randomly assigned to receive either sodium valproate or a matching placebo capsule.

  2. Step 2

    Start of Study Medication

    On the day you are randomized, you will begin taking one study capsule each day.

    The active capsule contains sodium valproate 640 mg in a modified‑release form; the placebo capsule looks the same but contains no active drug.

    The capsule is taken by mouth (oral route) with water, preferably at the same time each day.

  3. Step 3

    Daily Medication Intake

    You will continue to take one capsule daily for the entire study period.

    If you are assigned to the active arm, you will be receiving 640 mg of sodium valproate each day; if you are assigned to the placebo arm, you will take an identical capsule without active medication.

  4. Step 4

    Regular Clinic Visits for Safety Monitoring

    You will attend scheduled clinic visits, typically every four weeks, during which laboratory tests, ECG recordings, and vital‑sign measurements will be taken to monitor safety.

    The study staff will ask about any side effects or other health changes you may have experienced since the previous visit.

  5. Step 5

    Week 36 Evaluation

    At week 36, a comprehensive assessment will be performed.

    Key measurements include pulmonary vascular resistance (PVR), six‑minute walk distance (6MWD), and several scores that evaluate disease severity and heart function.

    These data are used to determine the primary and secondary outcomes of the trial.

  6. Step 6

    Continuation to Week 52

    After the week‑36 assessment, you will continue taking the study capsule daily until week 52.

    Additional follow‑up visits will be scheduled to repeat safety tests and to evaluate longer‑term changes in the same measurements performed at week 36.

  7. Step 7

    Final Assessment and Study Completion

    At the week‑52 visit, a final set of evaluations will be conducted, including the same laboratory, ECG, and functional tests performed earlier in the study.

    After this visit, the study medication will be stopped, and you will receive guidance on any further care needed.

Who can join the trial?

15 criteria

  • You must sign a written informed consent form, understand the study instructions, be able to return for scheduled visits, and stay in the study for its entire duration.
  • You must be between 18 and 80 years old at the time you sign the consent form.
  • Your body‑mass index (BMI) must be between 18 and 40 kg/m², which is a common way to compare weight to height.
  • You must have Group 1 pulmonary arterial hypertension (PAH) and belong to one of these sub‑groups:
    • Idiopathic PAH – cause unknown.
    • Heritable PAH – runs in families.
    • Drug or toxin‑induced PAH – caused by a medicine or chemical.
    • PAH associated with connective‑tissue disease (CTD).
    • PAH linked to a simple congenital heart shunt that was repaired at least one year ago.
    • You must have symptoms of PAH that limit your ability to exercise, and a qualified health professional (doctor, physician assistant, or nurse practitioner) must classify you as NYHA/WHO Functional Class II or III. This means your daily activities are slightly (class II) or moderately (class III) limited by the disease.
    • Your disease must score 6 or higher on the REVEAL Lite 2 assessment, a tool doctors use to estimate how severe PAH is.
    • You need to be taking stable doses of the usual PAH medicines (standard of care, SOC) for at least 90 days before screening. If you are on the drug sotatercept, you must have taken it continuously for at least 180 days before screening.
    • A screening test called right heart catheterization (RHC) must show:
      • a resting mean pulmonary artery pressure (mPAP) of at least 20 mm Hg,
      • a resting pulmonary vascular resistance (PVR) of at least 5 Wood units, and
      • a pulmonary capillary wedge pressure (PCWP) of 15 mm Hg or less.
      • Your distance walked in six minutes (6‑minute walk distance, 6MWD) must be at least 150 meters but less than 550 meters at screening. No more than 25 % of participants may have a distance between 450 and 550 meters.

Who cannot join the trial?

25 criteria

  • People whose pulmonary hypertension is not in WHO Group 1 (i.e., those classified as Group 2, 3, 4, or 5) cannot join the study.
  • Anyone with adult congenital heart disease (ACHD) is excluded.
  • People who have portopulmonary hypertension (high blood pressure in the lungs caused by liver disease) are not eligible.
  • Individuals with PAH caused by schistosomiasis, a history of an atrial septostomy (a surgical opening in the heart), or who have had a serious infection such as invasive fungal infection, pneumonia caused by Pneumocystis, a severe skin infection, an abscess, or a bloodstream infection within the past few months are excluded.
  • If a person has any other medical or psychiatric condition that the doctor thinks would make the study risky, difficult to complete, or could affect the results, they cannot participate.
  • People who have previously had a heart or heart‑lung transplant, are currently on a lung‑transplant waiting list, are expected to live less than 12 months, or are likely to need a lung transplant within the next 6 months are excluded.
  • Anyone with signs of left‑sided heart failure, including either a normal or high ejection fraction (the percentage of blood the heart pumps out with each beat) above 40 % together with a left atrial volume >34 mL/m², or a reduced ejection fraction below 40 %, cannot join.
  • People with more than mild problems of the mitral or aortic heart valves are excluded (moderate mitral valve leakage is allowed only if it is not caused by heart failure).
  • If an ultrasound of the heart (an echocardiogram) shows new abnormal movement of the left ventricle wall that suggests a recent heart artery problem within the past 6 months, the person is excluded (stable coronary artery disease is allowed).
  • Individuals with a significant chronic clotting disorder in the lungs or who have had a pulmonary embolism (blood clot in the lung) within the last 6 months cannot participate.
  • Anyone with a known history of pericardial constriction (tightening of the heart’s outer covering) or restrictive or congestive cardiomyopathy (a disease that makes the heart stiff or weak) is excluded.
  • People whose heart‑electrical test (ECG) shows a corrected QT interval (QTcF) longer than 480 milliseconds are not eligible.
  • Those with a personal or family history of long QT syndrome or sudden cardiac death are excluded.
  • A stroke (cerebrovascular accident) that occurred within the past 3 months disqualifies a participant.
  • Anyone who has had a heart attack, heart‑related procedures (such as stent placement or bypass surgery), or chest pain from heart disease within the past 6 months cannot join.
  • People who experienced an acute worsening of heart failure (decompensated heart failure) within the last 30 days are excluded.
  • Uncontrolled high blood pressure (systolic >160 mmHg or diastolic >100 mmHg) excludes a person from the trial.
  • Sustained low blood pressure (systolic <95 mmHg or diastolic <50 mmHg) also disqualifies a participant.
  • A resting heart rate that is consistently above 120 beats per minute, confirmed on at least three separate measurements, leads to exclusion.
  • Anyone who has taken another experimental drug within 30 days (or within five drug half‑lives) or is in another study that might interfere with this one cannot participate.
  • People who are regularly using sodium valproate, other anti‑epilepsy medicines, or any prohibited drug that cannot be stopped at the screening visit are excluded.
  • Those on anticoagulant or antiplatelet medications that cannot be stopped at screening (except a low dose of aspirin less than 125 mg) are not eligible.
  • If lung function tests show a forced expiratory volume/forced vital capacity ratio (FEV1/FVC) below 70 %, an FEV1 ≤50 % of predicted, or a total lung capacity (TLC) less than 70 % of predicted, the person is excluded. For TLC between 60‑69 %, a CT scan must show no more than mild interstitial lung disease.
  • Significant kidney problems, defined as an estimated glomerular filtration rate (eGFR) below 30 mL/min/1.73 m², exclude a participant.
  • Important liver problems, such as liver enzymes alanine aminotransferase (ALT) or aspartate aminotransferase (AST) more than twice the normal upper limit, or a bilirubin level more than 1.5 times the normal upper limit, lead to exclusion (except for people with Gilbert disease who have normal direct bilirubin).
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Investigated drugs

Sodium valproate is an oral medication in a modified‑release capsule that is being tested as an additional treatment for people with pulmonary arterial hypertension (PAH). In this study the drug is given together with the usual medicines that patients already take for PAH. Researchers want to see whether adding sodium valproate can lower the pressure in the lung arteries (measured as pulmonary vascular resistance) and whether it is safe and well tolerated. The trial is designed so that neither the participants nor the doctors know who receives the real drug and who receives a dummy pill, helping to give a clear picture of the drug’s effect.

What is already known about the treatment

  • Sodium valproate

    This medication is taken by mouth as a modified‑release capsule, with each dose containing 640 mg of the drug. It is an approved antiepileptic and mood‑stabilizing medicine that is also listed as an orphan drug for research in pulmonary arterial hypertension. Sodium valproate works by increasing the level of the calming brain chemical GABA and by inhibiting certain enzymes that affect gene activity, which may help relax blood vessels in the lungs. It belongs to the pharmacological class of anticonvulsants and histone deacetylase inhibitors.

  • Capsules similar to CS1 delayed release capsules

    This placebo looks like the active drug but contains no medicinal ingredient and is swallowed whole as an oral delayed‑release capsule. It is used only in clinical studies to provide a comparison for the test drug and has no therapeutic effect. Because it has no active substance, there is no mechanism of action or pharmacological class to describe. It serves as an inert control to help determine the safety and effectiveness of the test medication.

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 and stiff. This raises pressure in these vessels, causing the heart to work harder to pump blood through the lungs. Over time, the right side of the heart may enlarge as it tries to overcome the higher resistance. Symptoms usually appear gradually as the pressure increases. The disease can progress from mild pressure elevation to more severe narrowing and strain on the heart.
Trial detailsLast updated 14 Nov 2026
Age18+ yearsPhasePhase IITrial ID2026-526523-22-00Protocol codeCS1-005Estimated enrolment78 patientsSponsorCereno Scientific AB

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