Inclusion Criteria:
1. Treatment resistant hypertension defined as
1. an uncontrolled office BP (≥140/90 mmHg).
2. is on a regimen of ≥3 adequately dosed antihypertensive agents of different classes, including a diuretic, at maximum tolerated dose based on investigator judgment.
2. Stable diuretic and antihypertensive treatment for the previous 3 weeks.
3. Subject, or legal representative, has voluntarily signed and dated an Informed Consent Form, approved by the Independent Ethics Committee (IEC).
Exclusion Criteria:
1. Age \<18 years.
2. Estimated glomerular filtration rate (eGFR) \<20 ml/min/1.73m2 measured by the 2021 Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) creatinine formula and the 2012 cystatin C CKD-EPI formula.
3. A mean seated systolic blood pressure of at least 180 mmHg or a diastolic blood pressure of at least 110 mmHg.
4. Known secondary hypertension
5. An acute coronary syndrome, stroke, transient ischemic attack or cardiovascular surgery in the last 3 months.
6. Hospitalization for heart failure in the past 3 weeks.
7. Dialysis treatment or expected initiation of dialysis within 3 months of screening.
8. Women of child bearing potential who are not taking adequate contraception (i.e. \<1% failure rate).
9. Planned surgery in the next 12 weeks
10. Major surgery in the previous 4 weeks.
11. Use of prednisolone \>5 mg/day
12. Use of any other investigational drug.
13. Presence of significant comorbidities (e.g., advanced malignancy, advanced liver disease) with a life expectancy of less than 1 year.
14. A psychiatric, addictive or any disorder that compromises ability to give truly informed consent for participation in this study.
15. Known hypersensitivity to seaweed, corn, artichoke, grape, melon or to any of the excipients of Endocalyx.
16. Known hypersensitivity or allergies for milk, eggs, fish, crustacean shellfish, tree nuts, peanuts, wheat and soybeans.
17. Patients with rare hereditary problems of galactose intolerance, the Lapp lactase deficiency or glucose galactose malabsorption.
