Efficacy and safety of sodium zirconium cyclosilicate for hyperkalaemia: the randomized, placebo-controlled...

Sodium zirconium cyclosilicate (SZC, formerly ZS-9) is a selective K⁺ binder to treat adults with hyperkalaemia. HARMONIZE-Global examined the efficacy and safety of SZC among outpatients with hyperkalaemia from diverse geographic and ethnic origins.

This phase 3, randomized, double-blind, placebo-controlled study recruited outpatients with serum K⁺ ≥5.1 mmol/L (measured by point-of-care i-STAT device) at 45 sites in Japan, Russia, South Korea, and Taiwan. Following open-label treatment with thrice-daily SZC 10 g during a 48 h correction phase (CP), patients achieving normokalaemia (K⁺ 3.5-5.0 mmol/L) were randomized 2:2:1 to once-daily SZC 5 g, SZC 10 g, or placebo during a 28 day maintenance phase (MP). The primary endpoint was mean central-laboratory K⁺ level during days 8-29 of the MP. Of 267 patients in the CP, 248 (92.9%) entered the MP. During the CP, mean central-laboratory K⁺ was reduced by 1.28 mmol/L at 48 h vs. baseline (P < 0.001). During the MP (days 8-29), SZC 5 and 10 g once-daily significantly lowered mean central-laboratory K⁺ by 9.6% and 17.7%, respectively, vs. placebo (P < 0.001 for both). More patients had normokalaemia (central-laboratory K⁺ 3.5-5.0 mmol/L at day 29) with SZC 5 (58.6%) and 10 g (77.3%) vs. placebo (24.0%), with the greatest number of normokalaemic days in the 10-g group. The most common adverse events with SZC were mild or moderate constipation and oedema.

Normokalaemia achieved during the CP was maintained over 28 days with SZC treatment among outpatients with hyperkalaemia.