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Efficacy and Safety of Heparan Sulphate 120 mg Prolonged‑Release Tablets in Patients with Primary Chronic Venous Disease of the Lower Limbs

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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 primary chronic venous disease of the lower limbs, a condition in which the veins in the legs do not return blood to the heart efficiently, leading to swelling, discomfort, and skin changes. The investigational medication is labeled CLR-07-23 and consists of heparan sulfate formulated as a prolonged‑release tablet taken by mouth.

The purpose is to determine whether the study drug provides greater improvement than a placebo in reducing the severity of the disease. Participants will take one tablet each day for several months and will attend a series of clinic visits where clinicians will assess vein health, record pain using a Visual Analog Scale, and collect quality‑of‑life information with a Chronic Venous Insufficiency Quality of Life questionnaire. The primary measurement will be the change in the rVCSS, a score that rates how serious the vein symptoms are.

During the trial, any unwanted medical problems, known as Adverse Events, will be documented and reviewed to evaluate safety. The study is conducted in a double‑blind fashion, meaning neither the participants nor the investigators know who receives the active tablet or the placebo, which helps ensure unbiased results.

The research process

The trial runs in 8 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Randomization and Assignment

    After joining the study, you will be randomly assigned to receive either the active medication or a placebo. The assignment is double‑blind, meaning you and the study team will not know which one you receive.

  2. Step 2

    Baseline Assessment (Visit 1)

    During the first visit, called V1, you will undergo a physical examination and complete questionnaires that measure the severity of your venous disease, pain level, and quality of life.

    Your baseline scores on the Revised Venous Clinical Severity Score (rVCSS), the Visual Analog Scale (VAS) for pain, and the Chronic Venous Insufficiency Quality of Life (CIVIQ‑20) questionnaire will be recorded.

  3. Step 3

    Start of Study Medication

    You will begin taking one tablet containing 120 mg of heparan sulfate, or an identical tablet without active drug (placebo), by mouth.

    The tablet is a prolonged‑release formulation, designed to release the medication slowly over time.

    You will take the tablet as directed by the study protocol for the entire study period.

  4. Step 4

    First Follow‑up (Visit 2)

    At visit V2, you will return to the clinic for a safety check and to repeat the pain assessment using the VAS scale.

    Any adverse events or side effects will be recorded.

  5. Step 5

    Second Follow‑up (Visit 3)

    At visit V3, the study team will evaluate the change in your rVCSS score compared with the baseline measurement.

  6. Step 6

    Third Follow‑up (Visit 4)

    At visit V4, you will again complete the pain VAS assessment and report any new symptoms.

  7. Step 7

    Final Assessment (Visit 5)

    During the final visit, V5, you will undergo a full evaluation including the rVCSS score, the pain VAS, and the quality‑of‑life questionnaire (CIVIQ‑20).

    The difference between the V5 and V1 scores will be used to determine the effectiveness of the treatment.

  8. Step 8

    Safety Monitoring Throughout the Study

    At each visit, you will be asked about any adverse events, and the study staff will record them.

    Safety data will be collected for all participants, regardless of whether they received the active medication or placebo.

Who can join the trial?

5 criteria

  • Be at least 18 years old but not older than 80 years.
  • Have a diagnosis of primary chronic venous disease in the lower legs that is classified as stage C2 to C5 using the CEAP classification system, and this must be confirmed by a special ultrasound test called duplex ultrasonography.
  • Show clear signs of the disease (such as swelling or skin changes) and feel symptoms (like pain or heaviness), with a score of 4 or higher on the rVCSS score (a scale that measures how severe the condition is).
  • Not be using, and not plan to start using, compression therapy (tight stockings or bandages that squeeze the leg) on your own.
  • Sign a written informed consent form that has been approved by the study’s Ethics Committee.

Who cannot join the trial?

33 criteria

  • Use of a venoactive drug (medication that improves vein function) in the last month.
  • Having diabetic foot syndrome (foot problems caused by diabetes, such as ulcers or infections).
  • Having uncontrolled high blood pressure that cannot be lowered to ≤ 160 mmHg (top number) or ≤ 100 mmHg (bottom number) with treatment.
  • Having symptoms of poor blood flow (ischemia) in the lower legs.
  • Having any type of lymphedema (swelling caused by lymph fluid buildup), including primary, post‑injury, after surgery, after radiation, or cancer‑related.
  • Having received manual or instrument‑assisted lymphatic drainage (a therapy to move fluid out of swollen areas) in the last three months.
  • Having any invasive procedure (such as surgery or a major medical intervention) on the lower legs in the last six months.
  • Having a leg injury that has not fully healed.
  • Using oral or injectable blood‑thinning medicines (anticoagulants).
  • Using two antiplatelet drugs at the same time (medications that prevent platelets from clumping).
  • Using loop diuretics (a type of medication that helps the body get rid of excess water).
  • Regularly using compression therapy (tight stockings or bandages) or mechanical devices to reduce swelling in the last month.
  • Using estrogen or progesterone hormones or related medicines.
  • Using oral or injectable corticosteroids (anti‑inflammatory drugs) in the last six weeks.
  • Receiving treatment for chronic pain for 14 days or more.
  • Using psychiatric medicines that can cause fluid retention (such as certain antipsychotics or combination antidepressants).
  • Having severe obesity, defined as a body‑mass index (BMI) greater than 40 kg/m².
  • Having an active cancer or a cancer that has been in remission for less than five years.
  • Having blood‑forming (myeloproliferative) or immune system disorders.
  • Having any condition that makes the study drug or placebo unsafe to give (contraindications).
  • Being allergic to any ingredient in the study drug or placebo (hypersensitivity).
  • Being pregnant or breastfeeding.
  • Having moderate to severe heart failure (NYHA class III or IV) or congestive heart failure with swelling in the limbs.
  • Being a woman who could become pregnant and not using an effective birth‑control method for the entire study.
  • Having taken part in another drug or device trial within 30 days before screening.
  • Being unable to give informed consent because of legal or mental incapacity.
  • Being unable or unwilling to attend study visits or follow study requirements.
  • Having a kidney function test (eGFR) below 30 mL/min/1.73 m² or a history of chronic kidney disease.
  • Having liver enzyme levels (ALT or AST) more than three times the normal upper limit or a history of serious liver disease.
  • Having a deep vein clot in the leg, or a lingering blockage or backward flow in the deep veins after a previous clot.
  • Having a superficial vein clot in the leg within the past six months.
  • Having a birth‑related (congenital) abnormality of veins or lymphatic vessels.
  • Having any type of nerve damage (neuropathy), regardless of cause.
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Investigated drugs

Heparan sulfate (CLR‑07‑23) prolonged‑release tablets are oral tablets designed to slowly release the active ingredient, heparan sulfate, over time after you swallow them. In this study, the tablets are being tested to see if they can improve the symptoms of primary chronic venous disease in the legs, such as swelling, pain, or skin changes. Participants take the tablets according to the study schedule, and researchers compare how well they work and how safe they are compared with a placebo.

What is already known about the treatment

Heparan Sulfate 120 MG Prolonged-release tablets - The medicine is taken by mouth as a prolonged‑release tablet that slowly dissolves to give a steady dose. It is still being studied and is currently in a Phase III clinical trial, so it is not yet approved for general use. The drug is intended to help people with primary chronic venous disease of the lower limbs, a condition that causes swelling and pain in the legs. It works by providing heparan sulfate, a natural substance that supports healthy blood vessels, reduces clot‑forming activity and lowers inflammation, and it is classified as a glycosaminoglycan‑type vascular protective agent.

Investigated diseases

Primary chronic venous disease of the lower limbs - It is a long‑lasting condition in which the veins of the legs do not return blood to the heart efficiently. The weakened vein walls and faulty valves cause blood to pool, leading to swelling, heaviness, and aching in the lower legs. Over time, visible varicose veins may develop and the skin can become discolored or thickened. Minor skin changes can progress to venous eczema or small ulcers near the ankle. The disease usually worsens gradually if the underlying vein problems continue.
Trial detailsLast updated 25 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2024-514679-16-00Protocol codeCLR-07-23Estimated enrolment194 patients

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