A phase 3 multicenter open-label maintenance study to investigate the long-term safety of sodium zirconium cyclosilicate in Japanese subjects with hyperkalemia.

Background: Hyperkalemia is associated with many chronic diseases and renin-angiotensin-aldosterone system inhibitor therapy. Sodium zirconium cyclosilicate (SZC), an oral, highly selective cation-exchanger, is approved for the treatment of hyperkalemia.

Methods: This phase 3, multicenter, open-label, single-arm, flexible-dose study assessed the safety and efficacy of SZC in Japanese patients with hyperkalemia during a correction phase of up to 3 days and long-term (1 year) maintenance phase (NCT03172702).

Results: Overall, 150 patients received treatment during both study phases; the study population was generally representative of hyperkalemic Japanese patients in clinical practice. Most patients (78.7%) had three doses of SZC during the correction phase. All but one patient received SZC for ≤ 48 h before transitioning to the maintenance phase. In the maintenance phase, mean (standard deviation; SD) exposure to the study drug was 319.4 (98.1) days and mean (SD) dose was 7.38 (2.85) g/day. Adverse events (AEs) were reported in 131 patients (87.3%); most were mild. The most common treatment-related AEs as evaluated by investigators were constipation (6.7%), peripheral edema (4.0%), and hypertension (2.7%). In the correction phase, 78.7% of patients were normokalemic at 24 h and 98.7% within 48 h; ≥ 65.5% maintained normokalemia throughout the maintenance phase.

Conclusion: After a year of exposure, SZC treatment was well tolerated by Japanese patients and potassium levels were well controlled.