Characterization of structure and function of ZS-9, a K+ selective ion trap

HARMONIZE Asia: A Phase III Randomized Study to Investigate the Efficacy and Safety of Sodium Zirconium Cyclosilicate in Patients with Hyperkalemia in China

PURPOSE

Sodium zirconium cyclosilicate (SZC) is an oral potassium (K+)-lowering therapy for adults with hyperkalemia. HARMONIZE Asia (ClinicalTrials.gov identifier: NCT03528681) evaluated the efficacy and safety of SZC in Chinese patients with hyperkalemia.

METHODS

This Phase III, randomized, double-blind, placebo-controlled study recruited patients with serum K+ (sK+) ≥5.1 mmol/L at 35 sites in China. Patients received SZC 10 g three times daily (TID) for 24 or 48 hours during an open-label initial phase (OLP). Those patients achieving normokalemia (sK+ 3.5-5.0 mmol/L inclusive) entered a 28-day randomized (2:2:1) treatment phase (RTP) and received SZC 5 g, SZC 10 g, or placebo once daily. The primary endpoint was mean sK+ during RTP Days 8 to 29. Secondary endpoints included mean change in sK+ during the OLP, the proportion of patients who achieved normokalemia at the end of the OLP, the proportion that maintained normokalemia during the RTP, and time to recurrence of hyperkalemia.

FINDINGS

In total, 270 patients received SZC 10 g TID during the OLP; 256 (94.8%) completed the OLP. During the OLP, mean sK+ decreased by 1.1 mmol/L from baseline (5.9 mmol/L; P < 0.001) and 87.4% of patients achieved normokalemia. During the RTP, SZC 5 g and 10 g reduced mean sK+ versus placebo in a dose-dependent manner (each P < 0.001); least-squares means (95% confidence interval [CI]) sK+ were 4.9 mmol/L (4.7, 5.0), 4.4 mmol/L (4.3, 4.6), and 5.2 mmol/L (5.1, 5.4) for SZC 5 g, 10 g, and placebo, respectively. At RTP end, the proportions of patients who maintained normokalemia were 58.8% (SZC 5 g; odds ratio vs placebo, 2.5 [95% CI: 1.1, 6.1; P = 0.035]), 76.5% (SZC 10 g; odds ratio vs placebo, 6.3 [95% CI: 2.6, 15.3; P < 0.001]), and 36.8% for placebo. Risk of recurrent hyperkalemia was reduced by 61.0% and 84.0% with SZC 5 g and SZC 10 g, respectively, versus placebo (each P < 0.001). During the RTP, the incidence of adverse events was numerically higher with SZC 5 g (50.0% of patients) and 10 g (44.0%) versus placebo (36.0%); driven primarily by peripheral edema and constipation.

IMPLICATIONS

Both SZC doses demonstrated clinically relevant and statistically significant, dose-dependent efficacy in managing sK+ levels in Chinese patients with hyperkalemia, compared with placebo. SZC tolerability was broadly aligned with the known safety profile of SZC.

Synergistic Machine Learning Accelerated Discovery of Nanoporous Inorganic Crystals as Non-Absorbable Oral Drugs

Machine learning (ML) has taken drug discovery to new heights, where effective ML training requires vast quantities of high-quality experimental data as input. Non-absorbable oral drugs (NODs) have unique safety advantage for chronic diseases due to their zero systemic exposure, but their empirical discovery is still time-consuming and costly. Here, a synergistic ML method, integrating small data-driven multi-layer unsupervised learning, in silico quantum-mechanical computations, and minimal wet-lab experiments is devised to identify the finest NODs from massive inorganic materials to achieve multi-objective function (high selectivity, large capacity, and stability). Based on this method, a NH4-form nanoporous zeolite with merlinoite (MER) framework (NH4-MER) is discovered for the treatment of hyperkalemia. In three different animal models, NH4-MER shows a superior safety and efficacy profile in reducing blood K+ without Na+ release, which is an unmet clinical need in chronic kidney disease and Gordon's syndrome. This work provides a synergistic ML method to accelerate the discovery of NODs and other shape-selective materials.

Effectiveness, safety, and treatment pattern of sodium zirconium cyclosilicate in Chinese patients with hyperkalemia: interim analysis from a multicenter, prospective, real-world study (Actualize Study)

Introduction: Sodium zirconium cyclosilicate (SZC) is a nonabsorbed cation-exchanger approved in China for the treatment of hyperkalemia [HK; serum potassium (sK+) levels >5.0 mmol/L]. This is the first real-world study aimed to assess the effectiveness, safety, and treatment patterns of SZC in Chinese patients with HK. Here we present the results of the first interim analysis. Methods: This multicenter, prospective, cohort study included patients aged ≥18 years with documented HK within 1-year before study enrollment day. These patients were followed up for 6 months from the enrollment day after initiating SZC treatment. The treatment was categorized into correction phase (FAS-P1) and maintenance phase (FAS-P2 new and ongoing users). Subgroup analysis was performed in patients on hemodialysis (FAS-H). The primary objective was evaluation of safety profile of SZC; secondary objectives included assessment of treatment patterns of SZC and its effectiveness. Results: Of 421 screened patients, 193, 354, and 162 patients were enrolled in the FAS-P1, FAS-P2, and FAS-H groups, respectively. sK+ levels were reduced significantly from 5.9 mmol/L to 5.0 mmol/L after the correction phase. For the maintenance phase, the mean sK+ levels were maintained at 5.2 mmol/L and 5.0 mmol/L in the FAS-P2 new and ongoing user, respectively, and 5.3 mmol/L in the FAS-H subgroup. A considerable proportion of patients showed normokalemia after 48 h of SZC treatment (FAS-P1:51.3%) which was maintained up to 6 months in the maintenance phase (FAS-P2:44%). SZC was well-tolerated. Conclusion: SZC was effective and safe for the treatment of HK in real-world clinical practice in China.

A review of renal tubular acidosis

OBJECTIVE

To review the current scientific literature on renal tubular acidosis (RTA) in people and small animals, focusing on diseases in veterinary medicine that result in secondary RTA.

DATA SOURCES

Scientific reviews and original research publications on people and small animals focusing on RTA.

SUMMARY

RTA is characterized by defective renal acid-base regulation that results in normal anion gap hyperchloremic metabolic acidosis. Renal acid-base regulation includes the reabsorption and regeneration of bicarbonate in the renal proximal tubule and collecting ducts and the process of ammoniagenesis. RTA occurs as a primary genetic disorder or secondary to disease conditions. Based on pathophysiology, RTA is classified as distal or type 1 RTA, proximal or type 2 RTA, type 3 RTA or carbonic anhydrase II mutation, and type 4 or hyperkalemic RTA. Fanconi syndrome comprises proximal RTA with additional defects in proximal tubular function. Extensive research elucidating the genetic basis of RTA in people exists. RTA is a genetic disorder in the Basenji breed of dogs, where the mutation is known. Secondary RTA in human and veterinary medicine is the sequela of diseases that include immune-mediated, toxic, and infectious causes. Diagnosis and characterization of RTA include the measurement of urine pH and the evaluation of renal handling of substances that should affect acid or bicarbonate excretion.

CONCLUSIONS

Commonality exists between human and veterinary medicine among the types of RTA. Many genetic defects causing primary RTA are identified in people, but those in companion animals other than in the Basenji are unknown. Critically ill veterinary patients are often admitted to the ICU for diseases associated with secondary RTA, or they may develop RTA while hospitalized. Recognition and treatment of RTA may reverse tubular dysfunction and promote recovery by correcting metabolic acidosis.

Consensus statement on the management of hyperkalaemia-An Asia-Pacific perspective

Hyperkalaemia is an electrolyte imbalance that impairs muscle function and myocardial excitability, and can potentially lead to fatal arrhythmias and sudden cardiac death. The prevalence of hyperkalaemia is estimated to be 6%-7% worldwide and 7%-10% in Asia. Hyperkalaemia frequently affects patients with chronic kidney disease, heart failure, and diabetes mellitus, particularly those receiving treatment with renin-angiotensin-aldosterone system (RAAS) inhibitors. Both hyperkalaemia and interruption of RAAS inhibitor therapy are associated with increased risks for cardiovascular events, hospitalisations, and death, highlighting a clinical dilemma in high-risk patients. Conventional potassium-binding resins are widely used for the treatment of hyperkalaemia; however, caveats such as the unpalatable taste and the risk of gastrointestinal side effects limit their chronic use. Recent evidence suggests that, with a rapid onset of action and improved gastrointestinal tolerability, novel oral potassium binders (e.g., patiromer and sodium zirconium cyclosilicate) are alternative treatment options for both acute and chronic hyperkalaemia. To optimise the care for patients with hyperkalaemia in the Asia-Pacific region, a multidisciplinary expert panel was convened to review published literature, share clinical experiences, and ultimately formulate 25 consensus statements, covering three clinical areas: (i) risk factors of hyperkalaemia and risk stratification in susceptible patients; (ii) prevention of hyperkalaemia for at-risk individuals; and (iii) correction of hyperkalaemia for at-risk individuals with cardiorenal disease. These statements were expected to serve as useful guidance in the management of hyperkalaemia for health care providers in the region.

Sodium Zirconium Cyclosilicate in CKD, Hyperkalemia, and Metabolic Acidosis: NEUTRALIZE Randomized Study

Key Points

Sodium zirconium cyclosilicate effectively lowers serum potassium and maintains normokalemia in patients with CKD with concomitant hyperkalemia and metabolic acidosis. Despite high screen failure and small sample size, a nominally significant increase in sHCO3– was seen for sodium zirconium cyclosilicate versus placebo. Further studies on the basis of an appropriate cohort size may help validate the trend observed in sHCO3– levels, supporting these clinically relevant findings.

Background

Metabolic acidosis and hyperkalemia are common in CKD. A potential dual effect of sodium zirconium cyclosilicate (SZC), a selective binder of potassium in the gastrointestinal tract, on serum potassium (sK+) and serum bicarbonate (sHCO3−) was evaluated in patients with hyperkalemia and metabolic acidosis associated with CKD.

Methods

In the NEUTRALIZE study (NCT04727528 ), non-dialysis patients with stage 3–5 CKD, hyperkalemia (sK+>5.0 to ≤5.9 mmol/L), and metabolic acidosis (sHCO3− 16–20 mmol/L) received open-label SZC 10 g three times daily for ≤48 hours. Patients achieving normokalemia (sK+ 3.5–5.0 mmol/L) were randomized 1:1 to SZC 10 g or placebo daily for 4 weeks. The primary end point was patients (%) maintaining normokalemia at the end of treatment (EOT) without rescue. Secondary end points included mean change in sHCO3− at EOT (day 29) and patients (%) with normokalemia with a ≥3-mmol/L increase in sHCO3− without rescue.

Results

Of 229 patients screened, 37 were randomized (SZC, n =17; placebo, n =20). High screen failure led to early study termination. At EOT, 88.2% (SZC) versus 20.0% (placebo) of patients maintained normokalemia (odds ratio, 56.2; P = 0.001). Low enrollment rendered secondary end point P values nominal. SZC treatment provided nominally significant increases in sHCO3– versus placebo from day 15 onward. Patients with normokalemia with a ≥3-mmol/L increase in sHCO3− without rescue were 35.3% (SZC) and 5.0% (placebo; P < 0.05). No new safety concerns were reported.

Conclusions

SZC effectively lowered sK+ and maintained normokalemia, with nominally significant increases in sHCO3– observed for SZC versus placebo.

Advancing crush syndrome management: the potent role of Sodium zirconium cyclosilicate in early hyperkalemia intervention and survival enhancement in a rat model

Background: Crush Syndrome (CS), a severe trauma resulting from prolonged muscle compression, is commonly seen in large-scale disasters such as earthquakes. It not only causes localized tissue damage but also triggers electrolyte imbalances, particularly hyperkalemia, increasing the risk of early mortality. This study aims to assess the early intervention effects of Sodium Zirconium Cyclosilicate (SZC) on hyperkalemia in rat CS model. Methods: A rat CS model was established using a self-developed multi-channel intelligent small-animal crush injury platform. Rats in the experimental groups were treated with varying doses of SZC before compression and immediately post-decompression. The efficacy of SZC was evaluated by continuous monitoring of blood potassium levels and survival rates. Serum creatinine (Cre) and blood urea nitrogen (BUN) levels were analyzed, and renal damage was assessed through histopathological examination. Results: SZC treatment significantly reduced blood potassium levels and improved survival rates in rats. Compared to the placebo group, the SZC-treated rats showed a significant decrease in blood potassium levels at 6 and 12 h post-decompression, maintaining lower levels at 24 h. Biochemical analysis indicated no significant impact of SZC on renal function, with no notable differences in Cre and BUN levels between groups. Histopathological findings revealed similar levels of renal damage in both groups. Conclusion: SZC demonstrates significant early intervention effects on hyperkalemia in a rat model of crush injury, effectively improving survival rates without adverse effects on renal function. These results provide a new strategic direction for the clinical treatment of Crush Syndrome and lay the foundation for future clinical applications.

In situ potassium and hydrogen ion exchange into a cubic zirconium silicate microporous material

The selective separation of ions from aqueous systems, and even in the human body, is a crucial to overall environmental management and health. Nanoporous materials are widely known for their selective removal of cations from aqueous media, and therefore have been targeted for use as a pharmaceutical to treat hyperkalemia. This study investigated the detailed crystallographic molecular mechanisms that control the potassium ion selectivity in the nanoporous cubic zirconium silicate (CZS) related materials. Using time-resolved in situ Raman spectroscopy and time-resolved in situ X-ray diffraction, the selectivity mechanisms were determined to involve a synchronous cation-cation repulsion process that serves to open a favorable coordination bonding environment for potassium, not unlike the ion selectivity filter process found in potassium ion channels in proteins. Enhancement of ion exchange was observed when the CZS material was in a partial protonated state (≈3:1 Na:H), causing an expansion of the unit-cell volume, enlargement of the 7 member-ring window, and distortion of framework polyhedra, which allowed increased accessibility to the cage structures and resulted in rapid irreversible potassium ion exchange.

Recommendations for the management of hyperkalemia in patients receiving renin-angiotensin-aldosterone system inhibitors

Hyperkalemia is common in clinical practice and can be caused by medications used to treat cardiovascular diseases, particularly renin-angiotensin-aldosterone system inhibitors (RAASis). This narrative review discusses the epidemiology, etiology, and consequences of hyperkalemia, and recommends strategies for the prevention and management of hyperkalemia, mainly focusing on guideline recommendations, while recognizing the gaps or differences between the guidelines. Available evidence emphasizes the importance of healthcare professionals (HCPs) taking a proactive approach to hyperkalemia management by prioritizing patient identification and acknowledging that hyperkalemia is often a long-term condition requiring ongoing treatment. Given the risk of hyperkalemia during RAASi treatment, it is advisable to monitor serum potassium levels prior to initiating these treatments, and then regularly throughout treatment. If RAASi therapy is indicated in patients with cardiorenal disease, HCPs should first treat chronic hyperkalemia before reducing the dose or discontinuing RAASis, as reduction or interruption of RAASi treatment can increase the risk of adverse cardiovascular and renal outcomes or death. Moreover, management of hyperkalemia should involve the use of newer potassium binders, such as sodium zirconium cyclosilicate or patiromer, as these agents can effectively enable optimal RAASi treatment. Finally, patients should receive education regarding hyperkalemia, the risks of discontinuing their current treatments, and need to avoid excessive dietary potassium intake.

Potassium homeostasis and therapeutic intervention with sodium zirconium cyclosilicate: A model-informed drug development case study

Potassium (K+ ) is the main intracellular cation in the body. Elevated K+ levels (hyperkalemia) increase the risk of life-threatening arrhythmias and sudden cardiac death. However, the details of K+ homeostasis and the effects of orally administered K+ binders, such as sodium zirconium cyclosilicate (SZC), on K+ redistribution and excretion in patients remain incompletely understood. We built a fit-for-purpose systems pharmacology model to describe K+ homeostasis in hyperkalemic subjects and capture serum K+ (sK+ ) dynamics in response to acute and chronic administration of SZC. The resulting model describes K+ distribution in the gastrointestinal (GI) tract, blood, and extracellular and intracellular spaces of tissue, renal clearance of K+ , and K+ -SZC binding and excretion in the GI tract. The model, which was fit to time-course sK+ data for individual patients from two clinical trials, accounts for bolus delivery of K+ in meals and oral doses of SZC. The virtual population of patients derived from fitting the model to these trials was then modified to predict the SZC dose-response and inform clinical trial design in two new applications: emergency lowering of sK+ in severe hyperkalemia and prevention of hyperkalemia between dialysis sessions in patients with end-stage chronic kidney disease. In both cases, the model provided novel and useful insight that was borne out by the now completed clinical trials, providing a concrete case study of fit-for-purpose, model-informed drug development after initial approval of a drug.

Potassium-lowering effects of sodium zirconium cyclosilicate in the early post-transplant period

PROBLEM

Hyperkalemia is a serious condition among intra-abdominal transplant recipients, and the safety and efficacy of sodium zirconium cyclosilicate (SZC) for its management during the early post-transplant period are not well-established.

METHODS

Adults who received at least one 10-g dose of SZC within 14 days after an intra-abdominal transplant between January 2020 and July 2022 were included in our study. The primary outcome was the change in potassium (K+) levels following the first SZC dose. Other analyses explored adjunctive potassium-lowering therapies, potential gastrointestinal complications, and patient subgroups based on therapy and transplant type.

RESULTS

Among the recipients (n = 46), 11 were kidney recipients, 26 were liver recipients, seven were simultaneous liver/kidney recipients, and two were simultaneous pancreas/kidney recipients. The mean time to first dose post-transplant was 7.6 (±4) days, and the mean change in serum K+ after the initial SZC dose was -.27 mEq (p = .001). No gastrointestinal complications were observed following the SZC dose. The mean increase in serum bicarbonate was .58 mEq (p = .41) following the first dose of SZC. Four kidney recipients required dialysis following the SZC dose.

CONCLUSION

This study represents the largest investigation on the use of SZC in transplant recipients. A single 10-g dose of SZC reduced serum K+ levels in all subgroups, while the use of adjunctive K+-lowering therapies did not provide additional reduction beyond the effects of SZC. Importantly, no gastrointestinal complications were observed. These findings suggest that SZC may be a safe and promising therapeutic option for hyperkalemia management following solid organ transplantation.

Hyperkalemia: Pharmacotherapies and Clinical Considerations

Hyperkalemia has been defined as a condition where a serum potassium level is >5.5 mmol/l. It is associated with fatal dysrhythmias and muscular dysfunction. Certain medical conditions, such as chronic kidney disease (CKD), diabetes mellitus, and others, can lead to hyperkalemia. Many of the signs of hyperkalemia are nonspecific. A history and physical examination can be beneficial in the diagnosis of the condition. In this regard, certain characteristic electrocardiogram findings are associated with hyperkalemia along with laboratory potassium levels. In acute and potentially lethal conditions, hyperkalemia treatments include glucose and insulin, bicarbonate, calcium gluconate, beta-2 agonists, hyperventilation, and dialysis. There are several drugs, both old and new, that can additionally aid in the reduction of serum potassium levels. The present investigation evaluated some of these different drugs, including sodium polystyrene sulfonate (SPS), sodium zirconium cyclosilicate (SZC), and patiromer. These drugs each have increased selectivity for potassium and work primarily in the gastrointestinal (GI) tract. Each of these medications has unique benefits and contraindications. Clinicians must be aware of these medications when managing patients with hyperkalemia.

Practical patient care appraisals with use of new potassium binders in heart failure and chronic kidney diseases

Hyperkalaemia is a life-threatening condition leading to significant morbidity and mortality. It is common in heart failure and in chronic kidney disease (CKD) patients due to the diseases themselves, which often coexist, the high co-presence of diabetes, the fluctuations in renal function, and the use of some drugs [i.e. renin-angiotensin-aldosterone system (RAAS) inhibitors]. Hyperkalaemia limits their administration or uptitration, thus impacting on mortality. New K + binders, namely patiromer and sodium zirconium cyclosilicate (ZS-9), are an intriguing option to manage hyperkalaemia in heart failure and/or CKD patients, both to reduce its fatal effects and to let clinicians uptitrate RAAS inhibition. Even if their real impact on strong outcomes is still to be determined, we hereby provide a practical approach to favour their use in routine clinical practice in order to gain the correct confidence and provide an additive tool to heart failure and CKD patients' wellbeing. New trials are welcome to fill the gap in knowledge.

Comparison of effectiveness and safety of sodium polystyrene sulfonate and sodium zirconium cyclosilicate for treatment of hyperkalemia in hospitalized patients

PURPOSE

Potassium binders are frequently utilized for the treatment of hyperkalemia in hospitalized patients; however, there is limited data directly comparing individual agents. The purpose of this study was to compare the effectiveness and safety of sodium polystyrene sulfonate (SPS) and sodium zirconium cyclosilicate (SZC) for hyperkalemia treatment in hospitalized patients.

METHODS

This retrospective cohort study evaluated adult patients who were admitted within a 7-hospital health system and received SPS or SZC for a serum potassium level greater than 5.0 mEq/L. Patients receiving dialysis prior to SPS/SZC administration, those receiving other potassium-lowering medications within 6 hours prior to blood sampling for a repeat potassium level, and those started on kidney replacement therapy prior to sampling for a repeat potassium level were excluded.

RESULTS

Following evaluation of 3,903 patients, the mean reduction in serum potassium 4 to 24 hours after binder administration was 0.96 mEq/L with SPS and 0.78 mEq/L with SZC (P < 0.0001). The median dose of SPS was 30 g (interquartile range [IQR], 15-30 g) while the median (IQR) dose of SZC was 10 g (10-10 g). Resolution of hyperkalemia within 24 hours was achieved in a higher percentage of patients with use of SPS (74.9%) versus SZC (68.8%) (P < 0.001).

CONCLUSION

One of the largest comparisons of SPS and SZC conducted to date, this study demonstrated the effectiveness and safety of both agents. While a statistically greater reduction in serum potassium was observed with use of SPS, there was significant dosing variability among agents that limited the ability to directly compare specific doses. Further investigation is needed to determine the optimal dose of each agent for acute hyperkalemia management. This data will inform clinical decisions about the choice of potassium binder for acute hyperkalemia.

Potassium homeostasis - Physiology and pharmacology in a clinical context

Membrane voltage controls the function of excitable cells and is mainly a consequence of the ratio between the extra- and intracellular potassium concentration. Potassium homeostasis is safeguarded by balancing the extra-/intracellular distribution and systemic elimination of potassium to the dietary potassium intake. These processes adjust the plasma potassium concentration between 3.5 and 4.5 mmol/L. Several genetic and acquired diseases but also pharmacological interventions cause dyskalemias that are associated with increased morbidity and mortality. The thresholds at which serum K+ not only associates but also causes increased mortality are hotly debated. We discuss physiologic, pathophysiologic, and pharmacologic aspects of potassium regulation and provide informative case vignettes. Our aim is to help clinicians, epidemiologists, and pharmacologists to understand the complexity of the potassium homeostasis in health and disease and to initiate appropriate treatment strategies in dyskalemic patients.

Single Dose of Sodium Zirconium Cyclosilicate Versus Sodium Polystyrene Sulfonate in Hospitalized Patients With Hyperkalemia

BACKGROUND

Sodium zirconium cyclosilicate (SZC) is an inorganic zirconium silicate compound that selectively exchanges potassium for hydrogen and sodium. "Once" doses of SZC (with option to redose) in patients with hyperkalemia in hospitalized settings have not been evaluated. We hypothesized that a once dose of SZC would be non-inferior to sodium polystyrene sulfonate (SPS) in reducing serum potassium.

OBJECTIVE

The objective of our study is to evaluate the effect of a "once" dose of SZC when compared with SPS in reducing serum potassium levels.

METHODS

This was a retrospective analysis of patients who received either a "once" dose of SZC or single or repeated doses of SPS for hyperkalemia. The primary endpoint was mean absolute reduction in the first serum potassium value at least 4 hours after administration. The secondary efficacy endpoints were the rate of additional potassium-lowering therapies and the rate of normokalemia within 48 hours. Safety endpoints were the incidence of electrolyte abnormalities, hypoglycemia, hypertension, hypotension, and colonic necrosis.

RESULTS

A total of 260 patients were included in the analysis. The mean initial serum potassium was similar between groups (5.6 ± 0.4). The absolute serum potassium reduction was -0.88 ± 0.64 mEq/L and -0.75 ± 0.65 mEq/L with SZC and SPS, respectively. The "once" regimen of SZC demonstrated non-inferiority compared with SPS (P < 0.0001). The proportion of patients achieving normokalemia within 48 hours and the proportion of patients receiving additional potassium-lowering therapies did not differ between groups.

CONCLUSION AND RELEVANCE

The "once" dose regimen (with redose option) of SZC was non-inferior to the "once" or repeated dosing regimen of SPS with regard to absolute potassium reduction. There were no significant differences in the rate of additional potassium-lowering therapies and the rate of normokalemia at 48 hours. The incidence of hypertension was less common among patients who received SZC.

DIALIZE China: A Phase IIIb, Randomized, Placebo-Controlled Study to Reduce Predialysis Hyperkalemia With Sodium Zirconium Cyclosilicate in Chinese Patients

PURPOSE

The DIALIZE China study (Reduce Incidence of Pre-Dialysis Hyperkalaemia With Sodium Zirconium Cyclosilicate in Chinese Subjects) (NCT04217590) evaluated sodium zirconium cyclosilicate (SZC) for the management of hyperkalemia in Chinese patients undergoing hemodialysis.

METHODS

In the double-blind, Phase IIIb DIALIZE China study, Chinese adults with kidney failure and predialysis hyperkalemia (predialysis serum potassium [sK+] concentration >5.4 mmol/L after the long interdialytic interval [LIDI] and >5.0 mmol/L after ≥1 short interdialytic interval) who were receiving hemodialysis 3 times weekly were randomized to placebo or SZC 5 g once daily on nondialysis days. Doses were titrated towards maintaining normokalemia for 4 weeks (titration period) in 5-g increments up to 15 g. Primary efficacy was the proportion of responders during the 4-week evaluation period following the titration period (ie, those with a predialysis sK+ of 4.0-5.0 mmol/L for at least 3 of 4 hemodialysis visits following the LIDI) who did not require urgent rescue therapy.

FINDINGS

Overall, 134 adults (mean [SD] age, 55 [11.3] years) were randomized to SZC or placebo (n = 67 each). There were significantly more responders with SZC (37.3%) versus placebo (10.4%; estimated odds ratio [OR] = 5.10; 95% CI, 1.90-15.12; P < 0.001). The probability of all predialysis sK+ concentrations being 3.5 to 5.5 mmol/L was significantly higher with SZC versus placebo (estimated OR = 6.41; 95% CI, 2.71-15.12; P < 0.001). A greater proportion of patients achieved an sK+ of 3.5 to 5.5 mmol/L on at least 3 of 4 LIDI visits during evaluation with SZC (73.1%) versus placebo (29.9%). Serious adverse events occurred in 9.1% and 11.9% of patients in the SZC and placebo groups, respectively.

IMPLICATIONS

SZC treatment for predialysis hyperkalemia is effective and well tolerated in Chinese patients with kidney failure receiving hemodialysis.

CLINICALTRIALS

gov identifier: NCT04217590.

Rationale and design of CONTINUITY: a Phase 4 randomized controlled trial of continued post-discharge sodium zirconium cyclosilicate treatment versus standard of care for hyperkalemia in chronic kidney disease

Background

Individuals with chronic kidney disease (CKD) hospitalized with hyperkalemia are at risk of hyperkalemia recurrence and re-hospitalization. We present the rationale and design of CONTINUITY, a study to examine the efficacy of continuing sodium zirconium cyclosilicate (SZC)-an oral, highly selective potassium (K⁺) binder-compared with standard of care (SoC) on maintaining normokalemia and reducing re-hospitalization and resource utilization among participants with CKD hospitalized with hyperkalemia.

Methods

This Phase 4, randomized, open-label, multicenter study will enroll adults with Stage 3b-5 CKD and/or estimated glomerular filtration rate <45 mL/min/1.73 m², within 3 months of eligibility screening, hospitalized with a serum potassium (sK⁺) level of >5.0-≤6.5 mmol/L, without ongoing K⁺ binder treatment. The study will include an in-hospital phase, where participants receive SZC for 2-21 days, and an outpatient (post-discharge) phase. At discharge, participants with sK⁺ 3.5-5.0 mmol/L will be randomized (1:1) to SZC or SoC and monitored for 180 days. The primary endpoint is the occurrence of normokalemia at 180 days. Secondary outcomes include incidence and number of hospital admissions or emergency department visits both with hyperkalemia as a contributing factor, and renin-angiotensin-aldosterone system inhibitor down-titration. The safety and tolerability of SZC will be evaluated.Ethics approval has been received from all relevant ethics committees. Enrollment started March 2022 and the estimated study end date is December 2023.

Conclusions

This study will assess the potential of SZC versus SoC in managing people with CKD and hyperkalemia post-discharge.

Trial registration

ClinicalTrials.gov identifier: NCT05347693; EudraCT: 2021-003527-14, registered on 19 October 2021.

Steroidal or non-steroidal MRAs: should we still enable RAASi use through K binders?

Renin-angiotensin-aldosterone system inhibitors (RAASi) and mineralocorticoid receptor antagonists (MRAs) are important interventions to improve outcomes in patients with chronic kidney disease and heart failure, but their use is limited in some patients by the development of hyperkalemia. The risk of hyperkalemia may differ between agents, with one trial showing lower risk of hyperkalemia with the novel non-steroidal MRA finerenone compared with steroidal MRA spironolactone. Novel potassium binders, including patiromer and sodium zirconium cyclosilicate, are available interventions to manage hyperkalemia and enable continuation of RAASi and MRAs in patients who could benefit from these treatments. These agents bind free potassium ions in the lumen of the gastrointestinal tract to prevent the absorption of dietary potassium and increase potassium secretion. Several studies showed that potassium binders are effective compared with placebo for preventing hyperkalemia or steroidal MRA discontinuation, but none has evaluated whether this strategy impacts clinically important endpoints such as cardiovascular events. Due to this and other limitations related to cost, clinical availability, pill burden and patient selection, alternative potential strategies to mitigate hyperkalemia may be more practical. Conservative strategies include increased monitoring and use of loop or thiazide diuretics to increase urinary potassium excretion. Non-steroidal MRAs may have a lower risk of hyperkalemia than steroidal MRAs and have stronger anti-inflammatory and anti-fibrotic effects with resultant reduced risk of kidney disease progression. Sodium-glucose cotransporter-2 inhibitors also decrease hyperkalemia risk in patients on MRAs and decrease cardiovascular events and kidney disease progression. These may be better first-line interventions to obviate the need for potassium binders and offer additional benefits.

In pursuit of balance: renin-angiotensin-aldosterone system inhibitors and hyperkalaemia treatment

Hyperkalaemia is a life-threatening condition leading to significant morbidity and mortality. It is common in heart failure (HF) patients due to the disease itself, which often co-exists with chronic kidney disease and diabetes mellitus, the fluctuations in renal function, and the use of some drugs [i.e. renin-angiotensin-aldosterone system (RAAS) inhibitors]. In particular, hyperkalaemia opposes to their administration or up-titration, thus impacting on mortality. New K+ binders, namely, patiromer and sodium zirconium cyclosilicate, are an intriguing option to manage hyperkalaemia in HF patients, both to reduce its fatal effects and to let clinicians up-titrate RAAS inhibitors. Even if their real impact on strong outcomes is still to be determined, we hereby provide an overview of hyperkalaemia in HF and its current management. New trials are welcome to fill the gap in knowledge.

A randomized study to compare oral potassium binders in the treatment of acute hyperkalemia

BACKGROUND

The KBindER (K⁺ Binders in Emergency Room and hospitalized patients) clinical trial is the first head-to-head evaluation of oral potassium binders (cation-exchange resins) for acute hyperkalemia therapy.

METHODS

Emergency room and hospitalized patients with a blood potassium level ≥ 5.5 mEq/L are randomized to one of four study groups: potassium binder drug (sodium polystyrene sulfonate, patiromer, or sodium zirconium cyclosilicate) or nonspecific laxative (polyethylene glycol). Exclusion criteria include recent bowel surgery, ileus, diabetic ketoacidosis, or anticipated dialysis treatment within 4 h of treatment drug. Primary endpoints include change in potassium level at 2 and 4 h after treatment drug. Length of hospital stay, next-morning potassium level, gastrointestinal side effects and palatability will also be analyzed. We are aiming for a final cohort of 80 patients with complete data endpoints (20 per group) for comparative statistics including multivariate adjustment for kidney function, diabetes mellitus, congestive heart failure, metabolic acidosis, renin-angiotensin-aldosterone system inhibitor prescription, and treatment with other agents to lower potassium (insulin, albuterol, loop diuretics).

DISCUSSION

The findings from our study will inform decision-making guidelines on the role of oral potassium binders in the treatment of acute hyperkalemia.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT04585542 . Registered 14 October 2020.

An evaluation of sodium zirconium cyclosilicate: a new treatment option for hyperkalaemia in China

INTRODUCTION

Hyperkalemia is a common complication of chronic kidney disease (CKD), diabetes mellitus (DM), and heart failure (HF) that can lead to severe arrhythmias and sudden death and is associated with a higher risk of mortality. Therefore, the prevention and treatment of hyperkalemia is important. Sodium zirconium cyclosilicate (SZC), a new oral potassium-lowering drug, has offered an additional treatment option for Chinese patients with hyperkalemia since its launch in China in late 2019, and some experience has been accumulated regarding its efficacy and safety.

AREAS COVERED

In this review, the authors summarize the epidemiological features of hyperkalemia in China and review the clinical data regarding the use of sodium zirconium cyclosilicate in Chinese patients.

EXPERT OPINION

The prevalence of hyperkalemia is particularly high in Chinese patients with chronic kidney disease and heart failure. In China, recent clinical studies have shown that SZC rapidly reduces serum potassium, maintains normal potassium concentration, and is well tolerated and safe. Two Chinese expert consensus statements have recommended the use of SZC for the acute correction and chronic maintenance of potassium concentration.

Sodium zirconium cyclosilicate and metabolic acidosis: Potential mechanisms and clinical consequences

Metabolic acidosis is frequent in chronic kidney disease (CKD) and is associated with accelerated progression of CKD, hypercatabolism, bone disease, hyperkalemia, and mortality. Clinical guidelines recommend a target serum bicarbonate ≥ 22 mmol/L, but metabolic acidosis frequently remains undiagnosed and untreated. Sodium zirconium cyclosilicate (SZC) binds potassium in the gut and is approved to treat hyperkalemia. In clinical trials with a primary endpoint of serum potassium, SZC increased serum bicarbonate, thus treating CKD-associated metabolic acidosis. The increase in serum bicarbonate was larger in patients with more severe pre-existent metabolic acidosis, was associated to decreased serum urea and was maintained for over a year of SZC therapy. SZC also decreased serum urea and increased serum bicarbonate after switching from a potassium-binding resin in normokalemic individuals. Mechanistically, these findings are consistent with SZC binding the ammonium ion (NH₄⁺) generated from urea by gut microbial urease, preventing its absorption and, thus, preventing the liver regeneration of urea and promoting the fecal excretion of H⁺. This mechanism of action may potentially result in benefits dependent on corrected metabolic acidosis (e.g., improved well-being, decreased catabolism, improved CKD mineral bone disorder, better control of serum phosphate, slower progression of CKD) and dependent on lower urea levels, such as decreased protein carbamylation. A roadmap is provided to guide research into the mechanisms and clinical consequences of the impact of SZC on serum bicarbonate and urate.

Compared effectiveness of sodium zirconium cyclosilicate and calcium polystyrene sulfonate on hyperkalemia in patients with chronic kidney disease

Hyperkalemia is a well-recognized electrolyte abnormality in patients with chronic kidney disease (CKD). Potassium binders are often used to prevent and treat hyperkalemia. However, few studies have evaluated the difference in serum potassium (K⁺) level-lowering effect during the post-acute phase between the novel potassium binder, sodium zirconium cyclosilicate (ZSC), and conventional agents. This retrospective study included patients who received potassium binders (either ZSC or calcium polystyrene sulfonate [CPS]) in our hospital between May 2020 and July 2022. The patients were divided into the ZSC and CPS groups. After propensity score matching, we compared changes from baseline to the first follow-up point, at least 4 weeks after initiating potassium binders, in electrolytes including K⁺ level between the two groups. Of the 132 patients, ZSC and CPS were administered in 48 and 84 patients, respectively. After matching, 38 patients were allocated to each group. The ZSC group showed greater reduction in K⁺ levels than did the CPS group (P < 0.05). Moreover, a significant increase in serum sodium minus chloride levels, a surrogate marker for metabolic acidosis, was observed in the ZSC group (P < 0.05). Our results demonstrated that ZSC could potentially improve hyperkalemia and metabolic acidosis in patients with CKD.

Effects of different potassium-lowering regimens on acute hyperkalemia in hemodialysis patients: a real-world, retrospective study

Background

Hyperkalemia is a common and potentially life-threatening electrolyte disorder in maintenance hemodialysis (MHD) patients. This study aimed to evaluate the efficacy and safety of potassium-lowering regimens during treatment of acute hyperkalemia in MHD patients.

Methods

This retrospective real-world study (RWS) was conducted among 139 MHD patients. They were given different potassium-lowering regimens, viz. the insulin and glucose (IG) intravenous administration group (IG, 46 patients), the sodium polystyrene sulfonate group (SPS, 33 patients), the sodium zirconium cyclosilicate group (SZC, 38 patients), the IG + SZC group (22 patients). The primary efficacy end point was the rate of serum potassium decline at 2 h. The rates of adverse events were also compared.

Results

At 2 h, the mean ± SE change of serum potassium level was − 0.71 ± 0.32 mmol per liter (mmol/L) in IG group, − 0.43 ± 0.38 mmol/L in SPS group, − 0.64 ± 0.36 mmol/L in SZC group, − 1.43 ± 0.38 mmol/L in IG + SZC group (P < 0.01). The serum potassium level in IG + SZC group decreased more than that in the other three groups (P < 0.01), while the serum potassium level in SPS group decreased less than that in the other three groups (P < 0.05). There was no significant difference on the decrease of the serum potassium level between IG group and the SZC group (P = 0.374). The IG group and the IG + SZC group had higher rates of symptomatic hypoglycemia. The SPS group had significant decreases of serum calcium and serum magnesium after treatment.

Conclusions

Among MHD patients with acute hyperkalemia, SZC had similar potassium-lowering efficacy with IG intravenous administration at 2 h and superior on convenience and side-effects.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-022-03530-4.

Impact of Sodium Zirconium Cyclosilicate Therapy Cessation in Patients with Systolic Heart Failure

Background: Sodium zirconium cyclosilicate (SZC), a newly introduced potassium binder, is indicated for treating hyperkalemia. SZC-incorporated up-titration of renin-angiotensin system inhibitors and mineralocorticoid receptor antagonists has been recommended for those with systolic heart failure, whereas SZC is often terminated following the improvement of hyperkalemia in real-world practice. We aimed to investigate the impact of SZC cessation on the recurrence of hyperkalemia. Methods: Patients with systolic heart failure, in whom SZC was discontinued following improvement in hyperkalemia, were studied and compared to those who had continued SZC. All patients were followed for one year or until August 2022. The recurrent rates of hyperkalemia were compared between the two groups. Results: A total of 30 patients (median age 83 years, 53% men, median left ventricular ejection fraction 42%) were included. The one-year cumulative incidence of recurrent hyperkalemia was 93% in the group who discontinued SZC versus 22% in those who continued SZC (p = 0.032). In the group where SZC was withdrawn, doses of renin-angiotensin system inhibitors and mineralocorticoid receptor antagonists were less up-titrated, echocardiographic evidence of reverse remodeling occurred less, and readmission due to worsening heart failure tended to be higher compared to those who remained on SZC therapy. Conclusions: SZC cessation was associated with recurrent hyperkalemia and suboptimal medical therapy optimization compared to continuation of SZC therapy.

Hyperkalaemia in Heart Failure: Consequences for Outcome and Sequencing of Therapy

PURPOSE OF REVIEW

Heart failure (HF), in conjunction with common comorbidities such as chronic kidney disease and diabetes and medical therapies such as RAASi, predisposes to hyperkalaemia which may lead to hospitalisation and death. This paper aims to review the most current evidence surrounding the risks and management of hyperkalaemia in HF, with particular focus on recent research into RAASi including novel selective mineralocorticoid receptor blockers and novel potassium binders.

RECENT FINDINGS

The most recent evidence shows that even moderate hyperkalaemia may predispose to adverse outcomes such as hospitalisation and death. Furthermore, it may prevent patients from receiving optimal medical therapy for HF by reducing prescription of RAASi therapy. Novel potassium binders such as sodium zirconium cyclosilicate (SZC) and patiromer present potential options to reduce and prevent hyperkalaemia as well as maintain optimal RAASi dosing in HF. Management of hyperkalaemia in HF has advanced in recent years. New therapies such as SZC and patiromer are contributing to the management of acute hyperkalaemia and also access to life-saving RAASi therapies by tackling and preventing hyperkalaemia in the community.

Potassium Derangements: A Pathophysiological Review, Diagnostic Approach, and Clinical Management

Potassium is an essential cation critical in fluid and electrolyte balance, acid–base regulation, and neuromuscular functions. The normal serum potassium is kept within a narrow range of 3.5–5.2 meq/L while the intracellular concentration is approximately 140–150 meq/L. The total body potassium is about 45–55 mmol/kg; thus, a 70 kg male has an estimated ~136 g and 60 kg female has ~117 g of potassium. In total, 98% of the total body potassium is intracellular. Skeletal muscle contains ~80% of body potassium stores. The ratio of intracellular to extracellular potassium concentration (Ki/Ke) maintained by Na+/K+ ATPase determines the resting membrane potential. Disturbances of potassium homeostasis lead to hypo- and hyperkalemia, which if severe, can be life-threatening. Prompt diagnosis and management of these problems are important.

Optimizing Therapies in Heart Failure: The Role of Potassium Binders

Heart failure (HF) is a worrisome cardiac pandemic with a negative prognostic impact on the overall survival of individuals. International guidelines recommend up-titration of standardized therapies in order to reduce symptoms, hospitalization rates, and cardiac death. Hyperkalemia (HK) has been identified in 3–18% of HF patients from randomized controlled trials and over 25% of HF patients in the “real world” setting. Pharmacological treatments and/or cardio-renal syndrome, as well as chronic kidney disease may be responsible for HK in HF patients. These conditions can prevent the upgrade of pharmacological treatments, thus, negatively impacting on the overall prognosis of patients. Potassium binders may be the best option in patients with HK in order to reduce serum concentrations of K⁺ and to promote correct upgrades of therapies. In addition to the well-established use of sodium polystyrene sulfonate (SPS), two novel drugs have been recently introduced: sodium zirconium cyclosilicate (SZC) and patiromer. SZC and patiromer are gaining a central role for the treatment of chronic HK. SZC has been shown to reduce K⁺ levels within 48 h, with guaranteed maintenance of normokalemia for up to12 months. Patiromer has resulted in a statistically significant decrease in serum potassium for up to 52 weeks. Therefore, long-term results seemed to positively promote the implementation of these compounds in clinical practice due to their low rate side effects. The aim of this narrative review is to delineate the impact of new potassium binders in the treatment of patients with HF by providing a critical reappraisal for daily application of novel therapies for hyperkalemia in the HF setting.

Successful Conversion from Conventional Potassium Binder to Sodium Zirconium Cyclosilicate in a Patient with Refractory Constipation

Potassium binders are essential tools to treat hyperkalemia, particularly in patients with heart failure and chronic kidney disease. One of the drug-related complications is constipation, which further worsens heart failure by increasing afterload and decreases patients’ quality of life. We encountered an 82-year-old man with heart failure, chronic kidney disease, and hyperkalemia. A conventional potassium binder, calcium polystyrene sulfonate, ameliorated his hyperkalemia, whereas he became aware of refractory constipation. A conversion to a newly-introduced specific potassium binder, sodium zirconium cyclosilicate, improved persistent constipation, maintaining serum potassium levels within a normal range. Sodium zirconium cyclosilicate might be a preferable potassium binder to treat hyperkalemia, particularly in patients with heart failure and chronic kidney disease and those suffering from constipation.

Risk of hospitalization for heart failure in patients with hyperkalemia treated with sodium zirconium cyclosilicate versus patiromer

BACKGROUND

Sodium zirconium cyclosilicate (SZC) and patiromer were recently approved to treat hyperkalemia. Whether the initiation of SZC is associated with an increased risk of hospitalization for heart failure (HHF) compared to patiromer in routine practice remains unknown.

METHODS AND RESULTS

We conducted a new-user cohort study of non-dialysis adults who initiated SZC or patiromer using Optum's de-identified Clinformatics® Data Mart Database from May 2018 to September 2020. We performed propensity score (PS) matching in a variable ratio to match each SZC initiator with up to three patiromer initiators. The primary outcome was HHF. Cox proportional hazards regression models generated hazard ratios (HRs) with 95% confidence intervals (CIs) in the PS-matched groups. The cohort included 1,126 SZC initiators and 2,839 PS-matched patiromer initiators. The mean age was 72 years old, about 30% had a history of heart failure, and 85% had chronic kidney disease stages 3-5. The SZC group had 88 cases of HHF (incidence rate [IR] 35.8 per 100 person-years [PY]), and the patiromer group had 245 cases of HHF (IR 25.1 per 100 PY). The rate of HHF was numerically higher in the SZC initiators than patiromer initiators (HR 1.22, 95%CI 0.95, 1.56), but did not reach statistical significance. Results were consistent across sensitivity and subgroup analyses.

CONCLUSIONS

Initiation of SZC might be associated with an increased risk of hospitalization for heart failure compared to patiromer in routine practice. Larger comparative studies are needed to evaluate the safety of SZC in routine practice more precisely.

Potassium responses to sodium zirconium cyclosilicate in hyperkalemic hemodialysis patients: post-hoc analysis of DIALIZE

BACKGROUND

Sodium zirconium cyclosilicate (SZC) is an effective and well-tolerated treatment for hyperkalemia in maintenance hemodialysis patients. In post-hoc analyses of the phase 3b DIALIZE study, we examined the spectrum of potassium responses to SZC.

METHODS

Post-hoc analyses with SZC and placebo included: the number of long interdialytic interval (LIDI) visits during the 4-week evaluation period where patients attained pre-dialysis serum potassium (sK⁺) concentrations of 4.0-5.0 and 4.0-5.5 mmol/L; potassium gradient (the difference between pre-dialysis sK⁺ and dialysate potassium) at days 36, 43, 50, and 57, and change from baseline to the end of treatment (EOT) using categories of potassium gradient (1 to < 2, 2 to < 3, 3 to < 4, and ≥ 4 mmol/L).

RESULTS

A greater proportion of patients achieved the ranges of pre-dialysis sK⁺ concentration with SZC versus placebo for ≥1, ≥ 2, ≥ 3, and 4 LIDI visits over 4 weeks; 23.7 and 48.5% of patients in the SZC group achieved pre-dialysis sK⁺ concentrations of 4.0-5.0 and 4.0-5.5 mmol/L, respectively, at all 4 LIDI visits. Baseline mean potassium gradient was similar with SZC and placebo. At day 57, mean (standard deviation) potassium gradient was 2.78 (0.08) mmol/L with SZC and 3.52 (0.08) mmol/L with placebo; mean difference (95% confidence interval) was - 0.74 mmol/L (- 0.97 to - 0.52). A greater reduction in potassium gradient category from baseline towards lower-risk categories at EOT was observed with SZC versus placebo.

CONCLUSIONS

These analyses expand our knowledge of the spectrum of potassium responses with SZC in hyperkalemic hemodialysis patients.

TRIAL REGISTRATION

NCT03303521 .

Phase I Study of the Pharmacodynamics and Safety of Sodium Zirconium Cyclosilicate in Healthy Chinese Adults

Sodium zirconium cyclosilicate (SZC) is an effective potassium binder for patients with hyperkalemia. This single‐center, open‐label, phase I study (NCT03283267) characterized the pharmacodynamics and safety of SZC in Chinese individuals. Twenty‐two healthy Chinese adults (mean age, 33.5 years) randomized 1:1 received daily oral SZC 5 or 10 g for 4 days, following 4 days on a low‐sodium, high‐potassium diet (continued throughout the study). End points were mean change from baseline in 24‐hour urinary potassium (primary) and sodium excretion, and serum potassium concentration. Urinary potassium excretion significantly decreased with SZC 5 g (mean change [mmol], –13.0; P < .001) and 10 g (–15.4; P < .001). Although urinary sodium excretion decreased significantly with SZC 5 g (–11.5; P = .030), there was no significant change with SZC 10 g (–5.1; P = .299). Serum potassium concentrations decreased significantly with SZC 5 g (–0.14; P = .031) and 10 g (–0.20; P = .002). All treatment‐emergent adverse events were mild, and none were considered causally related to SZC. Over 4 days, the pharmacodynamics and safety of SZC were consistent in healthy Chinese adults with global studies and patients of Japanese ethnicity.

Effect of Sodium Zirconium Cyclosilicate on Serum Potassium and Bicarbonate in Patients with Hyperkalemia and Metabolic Acidosis Associated with Chronic Kidney Disease: Rationale and Design of the NEUTRALIZE Study

INTRODUCTION

Sodium zirconium cyclosilicate (SZC) is a selective potassium (K+) binder for hyperkalemia management that provides rapid and sustained correction of hyperkalemia. The NEUTRALIZE study is investigating whether SZC, in addition to correcting hyperkalemia and maintaining normal serum K+, can provide sustained increases in serum bicarbonate (HCO3-) in patients with hyperkalemia and metabolic acidosis associated with chronic kidney disease (CKD).

METHODS

This is a prospective, randomized, double-blind, placebo-controlled phase 3b study of US adults with stage 3-5 CKD not on dialysis with hyperkalemia (K+ >5.0-≤5.9 mmol/L) and low-serum HCO3- (16-20 mmol/L). In the open-label correction phase, all eligible patients receive SZC 10 g three times daily for up to 48 h. Patients who achieve normokalemia (K+ ≥3.5-≤5.0 mmol/L) are then randomized 1:1 to once-daily SZC 10 g or placebo for a 4-week, double-blind, placebo-controlled maintenance phase. The primary endpoint is the proportion of patients with normokalemia at the end of treatment (EOT) without rescue therapy for hyperkalemia. Key secondary endpoints include mean change in serum HCO3-, the proportion of patients with an increase in serum HCO3- of ≥2 or ≥3 mmol/L without rescue therapy for metabolic acidosis, and the proportion of patients with serum HCO3- ≥22 mmol/L at EOT.

CONCLUSIONS

NEUTRALIZE will establish whether SZC can provide sustained increases in serum HCO3- while lowering serum K+ in patients with hyperkalemia and CKD-associated metabolic acidosis and may provide insights on the mechanism(s) underlying the increased serum HCO3- with SZC treatment.

Clinical Implications of Sodium Zirconium Cyclosilicate Therapy in Patients with Systolic Heart Failure and Hyperkalemia

BACKGROUND

Sodium zirconium cyclosilicate (SZC), a newly introduced specific potassium binder, is introduced to treat hyperkalemia. However, the implications of SZC in up-titrating renin-angiotensin-aldosterone system inhibitors in patients with systolic heart failure remain unknown.

METHODS AND RESULTS

Patients with heart failure with left ventricular ejection fraction <50% and hyperkalemia who had completed 3-month SZC therapy were retrospectively included. Serum potassium levels, the dose of renin-angiotensin-aldosterone system inhibitors, and echocardiographic parameters during the 3-month SZC therapy as compared with the pretreatment 3-month period were investigated. A total of 24 patients (median 77 years old, 71% men, median left ventricular ejection fraction 41%) received a 3-month SZC therapy without any associated adverse events including hypokalemia. Compared with the pretreatment period, serum potassium levels decreased, doses of renin-angiotensin-aldosterone system inhibitors increased, and the left ventricular ejection fraction and plasma B-type natriuretic peptide levels improved following the 3-month SZC therapy (p < 0.05 for all).

CONCLUSIONS

SZC may be a promising therapeutic option to improve hyperkalemia, indirectly allowing up-titration of renin-angiotensin-aldosterone system inhibitors and facilitating reverse remodeling in patients with heart failure with a left ventricular ejection fraction <50% and hyperkalemia.

Optimization of RAASi Therapy with New Potassium Binders for Patients with Heart Failure and Hyperkalemia: Rapid Review and Meta-Analysis

(1) Background: The objective of this rapid review is to assess whether new potassium binders (NPBs) could enable the optimization of RAASi therapy more than usual care or placebo in patients with or at risk of heart failure and hyperkalemia. (2) Methods: We searched for RCTs that included patients with or at risk of hyperkalemia and patients treated with Patiromer or sodium zirconium cyclosilicate (ZSC). The comparators were placebo, usual care, and potassium binders with different doses or different treatment protocols. We searched the Cochrane CENTRAL, MEDLINE, and ClinicalTrials.gov databases. The risk of bias was assessed using the Cochrane risk of bias tool for RCTs. Data were pooled using the random effects model, and the fixed effects model was used for sensitivity analysis. (3) Results: We included 12 studies with 2800 enrolled patients. Only three of these trials (412 patients) were included in the meta-analysis. NPBs seemed to have an effect on the optimization of MRA therapy, with an RR (95% CI) of 1.24 (1.09, 1.42) (moderate certainty evidence); Patiromer seemed to have an effect on MRA optimization, with an RR (95% CI) or 1.25 (1.08, 1.45) (high certainty evidence). ZSC seemed to have no effect on enabling MRA therapy, with an RR (95% CI) of 1.19 (0.89, 1.59) (low certainty evidence). The AEs in HF patients with hyperkalemia treated with Patiromer were GI disorders and hypomagnesemia. ZSC The AEs included chronic cardiac failure, hypokalemia, and edema. (4) Conclusions: This meta-analysis included three studies with a small number of patients and a short follow-up period (1–3 months). The evidence of the effect of NPBs on MRA optimization had a moderate certainty for imprecision. Data on the effect on MRA optimization and less severe AEs in long-term treatment seem to suggest the use of Patiromer for the optimization of MRA therapy in patients with or at risk of heart failure and hyperkalemia. Future adequately powered RCTs are needed to assess the benefits and potential harms of potassium binders.

The Role of Patiromer in Delaying the Onset of Renal Replacement Therapy in Patients with Advanced Renal Failure

Patients with chronic kidney disease (CKD) are at an increased risk of developing hyperkalemia, which can be potentially life threatening. Hyperkalemia is frequently encountered with renin-angiotensin-aldosterone system inhibitor (RAASi) therapy use in patients with CKD and often results in the underdosing or discontinuation of these drugs. RAASi therapy has been proven to delay the progression of CKD, ameliorate proteinuria, and reduce the overall risk of cardiovascular morbidity and mortality. Patiromer is a sodium-free, potassium-binding polymer used for the treatment of hyperkalemia. We present a case series of four patients with Stage 4 or 5 CKD in whom the initiation of dialysis was delayed with the use of patiromer. For one patient, dialysis was delayed by 18 months, whereas the remaining three patients, in whom hyperkalemia was one of the main complications, remain dialysis independent to date.

Hyperkalemia with RAAS inhibition: Mechanism, clinical significance, and management

Renin-angiotensin-aldosterone system (RAAS) inhibitors are evidence-based treatments for a number of conditions including hypertension, diabetes mellitus, chronic kidney disease, and congestive heart failure. Among the most common adverse effects of RAAS inhibitors is hyperkalemia which results from either reduced secretion of aldosterone or increased resistance to aldosterone. Many of the conditions for which RAAS inhibitors are recommended further amplify the risk for hyperkalemia in and of themselves. RAAS inhibitor-related hyperkalemia is associated with an increased risk for cardiovascular events, hospitalizations, and death. Yet discontinuation of RAAS inhibitors for patients with chronic kidney disease and congestive heart failure is also associated with an increased risk for cardiovascular events, hospitalizations, and death. Therefore, clinicians are often left to struggle with the dilemma of the best management approach to RAAS inhibitor-related hyperkalemia. The ideal solution involves pharmacotherapies that are safe and effective in mitigating hyperkalemia and allow patients to continue to receive the beneficial effects from RAAS inhibitors. In this regard, modern pharmacologic agents such as patiromer and zirconium cyclosilicate are providing a mechanism whereby physicians are better equipped to maintain their patients on RAAS inhibitors.

The LIFT trial: study protocol for a double-blind, randomised, placebo-controlled trial of K+-binder Lokelma for maximisation of RAAS inhibition in CKD patients with heart failure

BACKGROUND

CKD is common in heart failure (HF) and associated with morbidity and mortality, yet life-prolonging medications such as renin-angiotensin-aldosterone inhibitors (RAASi) are underused due to risk of hyperkalaemia. Sodium zirconium cyclosilicate (SZC) is a potassium-binding medication that has been shown to reduce incidence of hyperkalaemia in CKD, non-CKD, and HF populations, which we propose will support maximisation of RAASi therapy.

METHODS

We propose a 1:1 randomised, double-blind, placebo-controlled trial in which participants will receive either SZC or placebo. We will up-titrate participants' RAASi therapy while monitoring their serum potassium levels and adjusting their SZC dose if necessary. Participants with CKD and HF will be recruited from CKD and HF clinics at St George's Hospital. The total study period will be 18 months; 130 participants will be enrolled for approximately two months each following screening. Our primary outcome will be the proportion of participants who achieve maximum RAASi dose while maintaining normokalaemia. Secondary outcomes include participants reaching maximum RAASi dose without severe hyperkalaemia; time from randomisation to hyperkalaemia; time from randomisation to severe hyperkalaemia; number of RAASi dose escalations per participant; final doses of RAASi therapy; changes in quality of life score, eGFR, ACR, serum sodium, troponin T; number and duration of hospital admissions; and within-participant change in serum potassium compared to baseline.

DISCUSSION

This trial will be the first to examine the use of SZC for the maximisation of RAASi dosing in patients with advanced CKD and HF. We will assess the impact of achieving target RAASi dosing on hospital admission rates and duration of stay, with the hope that optimum RAASi treatment will translate into reduced morbidity and improved QoL. If clinical benefit is demonstrated, we hope that the joint multidisciplinary CKD-HF approach will be expanded.

TRIAL REGISTRATION

EudraCT number 2020-002946-18. Registered on 08 June 2020. Online record pending.

Sodium zirconium cyclosilicate for the management of chronic hyperkalemia in kidney disease, a novel agent

INTRODUCTION

Hyperkalemia is a common finding in patients with advanced kidney disease for multiple reasons. Renin-Angiotensin-Aldosterone-System Inhibitors (RAASi) that are indicated for slowing down progression of kidney disease are often associated with hyperkalemia which becomes a limiting factor in their use and titration to the maximum dose. Having a safe, effective, tolerable, and affordable potassium binder can help optimize RAAS inhibition in the setting of kidney disease.

AREAS COVERED

Although sodium polystyrene sulfonate has been a mainstay of acute management of hyperkalemia for decades, evidence regarding its efficacy is limited, and its chronic use is not routinely recommended for concerns regarding toxicity. The concern of gastrointestinal (GI) adverse effects with sodium polystyrene sulfonate has spurred the development of alternatives. Sodium zirconium cyclosilicate (SZC) is a promising agent that selectively binds potassium in the gut and eliminates it, while being safe for chronic use based on 1 year of data. Even though we do not have head-to-head studies among the three currently available binders, SZC stands out in rapidity of onset and efficacy.

EXPERT OPINION

In this review, we summarize the general management of hyperkalemia, including new agents. We review the pre-clinical and clinical data relating to sodium zirconium cyclosilicate.

Patiromer and Sodium Zirconium Cyclosilicate in Treatment of Hyperkalemia: A Systematic Review and Meta-Analysis

Background

Patiromer and sodium zirconium cyclosilicate (SZC) are newer options for hyperkalemia treatment. This systematic review and meta-analysis were conducted to assess the safety and side effect profile of patiromer and SZC compared with placebo or other standards of care in the management of hyperkalemia.

Methods

We searched electronic databases for relevant articles. The screening was performed independently and data were extracted among the selected studies. We performed a statistical analysis on Revman 5.4 software. The odds ratio (OR) was used for outcome estimation with a 95% CI.

Results

Patiromer had lower rates of hyperkalemia (OR = 0.44; 95% CI, 0.22–0.89) compared with standard of care. The analysis showed no significant differences between the 2 groups in terms of overall adverse effects, any serious/specific adverse effects, or treatment discontinuation as a result of adverse effects. Comparing the SZC-10 group with standard of care showed no significant differences in the occurrence of hyperkalemia during treatment, overall adverse effects, any serious/specific adverse effects, or treatment discontinuation as a result of adverse effects but showed a higher rate of edema in the treatment group (OR = 6.77; 95% CI, 1.03–44.25). Similarly, no significant differences were seen between the 2 SZC doses for the occurrence of any adverse effects, hyperkalemia, constipation, diarrhea, or urinary tract infection, whereas edema was higher among patients receiving SZC-10 (OR = 3.13; 95% CI, 1.19–8.27).

Conclusions

In patients with acute hyperkalemia, SZC is the drug of choice due to its more rapid reduction of serum potassium level, whereas in patients with chronic hyperkalemia, patiromer appears to be the drug of choice because SZC is associated with an increase in edema, likely due to an increase in sodium absorption, which could have important adverse consequences in patients with chronic kidney disease and or heart failure. Thus, both drugs were found to be safe while treating hyperkalemia. (Curr Ther Res Clin Exp. 2021; 82:XXX–XXX)

Hyperkalaemia in Heart Failure

Hyperkalaemia has become an increasingly prevalent finding in patients with heart failure (HF), especially with renin–angiotensin–aldosterone system (RAAS) inhibitors and angiotensin–neprilysin inhibitors being the cornerstone of medical therapy. Patients living with HF often have other comorbidities, such as diabetes and chronic kidney disease, which predispose to hyperkalaemia. Until now, we have not had any reliable or tolerable therapies for the treatment of hyperkalaemia to facilitate implementation or achievement of target doses of RAAS inhibition. Patiromer sorbitex calcium and sodium zirconium cyclosilicate are two novel potassium-binding resins that have shown promise in the management of patients predisposed to developing recurrent hyperkalaemia, and their use may allow for further optimisation of guideline directed medical therapy.

Potassium Metabolism and Management in Patients with CKD

Potassium (K), the main cation inside cells, plays roles in maintaining cellular osmolarity and acid-base equilibrium, as well as nerve stimulation transmission, and regulation of cardiac and muscle functions. It has also recently been shown that K has an antihypertensive effect by promoting sodium excretion, while it is also attracting attention as an important component that can suppress hypertension associated with excessive sodium intake. Since most ingested K is excreted through the kidneys, decreased renal function is a major factor in increased serum levels, and target values for its intake according to the degree of renal dysfunction have been established. In older individuals with impaired renal function, not only hyperkalemia but also hypokalemia due to anorexia, K loss by dialysis, and effects of various drugs are likely to develop. Thus, it is necessary to pay attention to K management tailored to individual conditions. Since abnormalities in K metabolism can also cause lethal arrhythmia or sudden cardiac death, it is extremely important to monitor patients with a high risk of hyper- or hypokalemia and attempt to provide early and appropriate intervention.