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Hyperkalemia Drug Shows Promise in Phase III Trial
Data presented at annual kidney meeting (November 9)
Promising results have been reported from a pivotal phase 3 III study of ZS-9 (ZS Pharma), an investigational treatment for hyperkalemia.
Preliminary analyses of safety and efficacy results from the trial’s acute phase showed that the study met its primary endpoint, demonstrating a rapid, statistically significant reduction in serum potassium (K+) over the initial 48 hours. These results confirm positive data from a double-blind, placebo-controlled phase II trial that also met its primary efficacy endpoint.
The results from both studies were presented at the American Society of Nephrology’s (ASN) Annual Scientific Meeting (Kidney Week 2013), held Nov. 5–10 in Atlanta, Georgia.
The phase III trial enrolled 753 patients with hyperkalemia (potassium levels: 5 to 6.5 mEq/L), including patients with chronic kidney disease, heart failure, and diabetes, and those on renin-angiotensin-aldosterone system (RAAS) inhibitor therapy. The patients were randomly assigned to receive one of four doses of ZS-9 (1.25 g, 2.5 g, 5 g, or 10 g) or placebo, administered three times daily for the initial 48 hours (acute phase). The primary endpoint was the rate of change in serum K+ from baseline throughout the 48-hour acute phase. The patients normalized in the acute phase were then randomly assigned to receive ZS-9 (1.25 g, 2.5 g, 5 g, or 10 g) or placebo administered once-daily for 12 days (the subacute phase).
The trial met its primary efficacy endpoint for the acute phase at doses of 2.5 g, 5 g, and 10 g compared with placebo (P = 0.0009, P < 0.0001, and P < 0.0001, respectively). The mean serum K+ reduction was –0.73 mEq/L at the 10-g dose at 48 hours (P < 0.0001) — 14 hours after the last dose. Across all doses, the incidence of adverse events was similar to that of placebo. Specifically, the gastrointestinal (GI) adverse event rate was 3.5% in patients treated with ZS-9 compared with 5.1% in those given placebo.
Source: ZS Pharma; November 9, 2013.