Randomized, Placebo-crontrolled Clinical Trial Evaluating the Efficacy and Safety of Heparan Sulfate 120 mg Prolonged-Release Tablets Compared With Placebo in Patients With Chronic Venous Disease (CLR-18)

Inclusion Criteria:

• Participants with an age ≥ 18 and ≤ 80 years
• Diagnosed primary venous disease of the lower limbs in stage C2 - C5 according to the CEAP classification, involvement of the venous system of the lower limbs is verified by duplex ultrasonography
• Presence of objective signs and subjective symptoms of the disease (classified according to rVCSS score ≥ 4)
• Participants not using or planning to use compression therapy by their own decision
• Provision of written informed consent as approved by the Ethics Committee (EC).

Exclusion Criteria:

• Use of a venoactive drug in the last month
• Regular use of compression therapy or use of mechanical devices for reduction of edema in the last month
• Heart Failure (NYHA class III and IV), congestive heart failure with peripheral edema
• eGFR < 30 mL/min/1.73 m² at screening or chronic kidney disease documented in the medical history
• ALT or AST more than 3 times the upper limit of normal range at screening or advanced liver disease documented in the medical history
• Deep venous thrombosis lower limb thrombosis and / or documented residual venous obstruction or deep venous reflux due to post-thrombotic alterations in the deep venous system
• Superficial venous thrombosis of the lower limbs in the previous 6 months
• Congenital venous/lymphatic malformation
• Neuropathy of any aetiology
• Diabetic foot syndrome
• Refractory (uncontrollable) hypertension (inability to therapeutically achieve a systolic blood pressure ≤ 160 mmHg or a diastolic blood pressure ≤ 100 mmHg)
• Symptomatic ischemic disease of lower limbs
• Lymphoedema: primary, posttraumatic, postoperative, post-radiation, malignant
• Manual/instrumental lymphatic drainage in the last 3 months
• Invasive procedure on the lower limbs in the last 6 months
• Trauma of the lower extremity that has not fully healed
• Use of oral/parenteral anticoagulants
• Use of dual antiplatelet therapy
• Use of loop diuretics

• Use of oestrogens or progesterone and its derivates

  -. Use of oral/parental corticosteroids in the last 6 weeks

• Chronic pain treatment ≥ 14 days
• Use of psychopharmaceuticals affecting fluid retention (antipsychotics, combined antidepressants)
• Severe obesity (BMI > 40 kg/m2)
• Participants with active malignant disease or malignant disease in remission for less than 5 years
• Myeloproliferative or immune disorders
• Contraindications to the IMP/Placebo administration
• Hypersensitivity to the IMP/Placebo excipients. General Conditions
• Pregnant or breastfeeding women
• Women of child-bearing potential not using at least one effective contraceptive method for the entire trial

• Participation in other investigational drug or device clinical trials within 30 days prior to study screening

  -. Participants legally or mentally incapacitated unable to give informed consent for the participation in this trial

• Participants unable or unwilling to comply with appointments or all protocol requirements.