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The William Harvey Research Institute - Faculty of Medicine and Dentistry

ORTIZ - Optimising RASi Therapy with SZC

Trial objective:  To determine whether 3 months treatment with SZC versus placebo enables RASi (Irbesartan) maximisation in a cohort of patients with diabetic kidney disease.
Disease area: 
Diabetic Kidney Disease
  In set-up
Chief Investigator: 
Dr Kieran McCafferty
Sponsor: Barts Health NHS Trust
Funder: Astra Zeneca

Study summary

ORTIZ is a multi-centre, placebo-controlled, double-blind randomised clinical trial evaluating the effectiveness of sodium zirconium cyclosilicate versus placebo to enable safe optimisation of RASi therapy in patients with diabetic kidney disease. The treatment period with SZC/placebo (powder for oral suspension) is 12 weeks, followed by 2 weeks follow up.

For people with diabetes and proteinuria (protein in the urine), using medications which inhibit something called the renin angiotensin system (RASi) have been a key treatment for over 20 years. These medicines help with high blood pressure and can reduce protein in the urine, slow the decline in kidney function, delay the need for dialysis and help protect the heart and kidneys. These RASi medicines which may also be called ACE inhibitors (ACEi) or angiotensin receptor blockers (ARB) are very commonly used in people with diabetes and kidney disease. However, an important side effect of these medications is hyperkalemia (a raised level of potassium in the blood). Having too much potassium in the blood can be dangerous as it can affect the rate and rhythm of the heart. This has meant that many patients are not able to take these medications or are unable to use the medications at the maximum dose to get the most benefit from these medicines.

There is a new medication, sodium zirconium cyclosilicate (SZC) which has been shown to lower potassium levels in patients with diabetes who are on RASi, by binding potassium in the intestines (gut). This medicine is recommended by NICE, the National Institute for Health and Care Excellence to help patients with diabetes and kidney disease get an optimised dose of RASi therapy.

Sample size and duration

116 patients will be recruited over a period of 18 months at the five participating sites: Barts Health NHS Trust, Imperial College Healthcare NHS Trust, St George’s University Hospital NHS Trust, King’s College London Hospital NHS Trust.


For further information about the study, please contact a member of the research team: 

Dr Kieran McCafferty

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