Sodium zirconium cyclosilicate (SZC) can lower serum potassium in hyperkalemic solid organ transplant recipients taking calcineurin inhibitors without significantly compromising tacrolimus pharmacokinetics, according to investigators.

Renal dysfunction and use of calcineurin inhibitors and sulfamethoxazole/trimethoprim in transplant recipients can lead to hyperkalemia. Ryan Winstead, PharmD, and colleagues from Virginia Commonwealth University Health in Richmond, Virginia, assessed 35 transplant recipients (16 kidneys, 14 livers, 2 hearts, 2 combined kidney and liver, and 1 combined kidney and heart) taking SZC after transplant (including 9 as inpatients) for key outcomes. Dosing ranged from once to thrice daily taken 2 hours apart from other medications.

Mean serum potassium at baseline was 5.9 mEq/L. Over 7 days of treatment, mean serum potassium levels decreased significantly by 1.3 mEq/L, according to results published in Clinical Transplantation. Concurrently, mean sodium and bicarbonate levels increased by 1.70 and 1.60 mEq/L, respectively. The mean tacrolimus concentration decreased only 0.54 ng/mL.

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SZC was discontinued once hyperkalemia and renal function improved or sulfamethoxazole/trimethoprim was stopped. Two patients reported mild edema.

“Further studies are needed to study whether ZS-9 [sodium zirconium cyclosilicate] impacts other commonly used transplant medications such as mycophenolate,” Dr Winstead’s team stated.

Disclosure: One study author declared an affiliation with Relypsa.

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Winstead RJ, Demehin M, Yakubu I, et al. Sodium zirconium cyclosilicate use in solid organ transplant recipients and its effect on potassium and immunosuppression [published online January 28, 2020]. Clin Transplant. doi: 10.1111/CTR.13791