A phase 2 study on the treatment of hyperkalemia in patients with chronic kidney disease suggests that the selective potassium trap, ZS-9, is safe and efficient

Clinical utility of patiromer, sodium zirconium cyclosilicate, and sodium polystyrene sulfonate for the treatment of hyperkalemia: an evidence-based review

INTRODUCTION

Hyperkalemia is a serious medical condition that often manifests in patients with chronic kidney disease and heart failure. Renin-angiotensin-aldosterone system inhibitors are known to improve outcomes in these disease states but can also cause drug-induced hyperkalemia. New therapeutic options exist for managing hyperkalemia in these patients which warrant evidence-based evaluation.

AIM

The objective of this article was to review the efficacy and safety evidence for patiromer, sodium zirconium cyclosilicate (ZS9), and sodium polystyrene sulfonate (SPS) for the treatment of hyperkalemia.

EVIDENCE REVIEW

Current treatment options to enhance potassium excretion are SPS and loop diuretics, which are complicated by ambiguous efficacy and known toxicities. Patiromer and ZS9 are new agents designed to address this treatment gap. Both unabsorbable compounds bind potassium in the gastrointestinal (GI) tract to facilitate fecal excretion. The capacity to bind other medications in the GI tract infers high drug-drug interaction potential, which has been demonstrated with patiromer but not yet investigated with ZS9 or SPS. Phase II and III clinical trials of patiromer and ZS9 demonstrated clear evidence of a dose-dependent potassium-lowering effect and the ability to initiate, maintain, or titrate renin-angiotensin-aldosterone system inhibitors. There is limited evidence base for SPS: two small clinical trials indicated potassium reduction in chronic hyperkalemia. All agents may cause adverse GI effects, although they are less frequent with ZS9. Concerns remain for SPS to cause rare GI damage. Electrolyte abnormalities occurred with patiromer and SPS, whereas urinary tract infections, edema, and corrected QT-interval prolongations were reported with ZS9.

CONCLUSION

Patiromer and ZS9 have improved upon the age-old standard SPS for the treatment of hyperkalemia. Additional research should focus on drug-drug interactions in patients on multiple medications, incidence of rare adverse events, and use in high-risk populations.

Long-term efficacy of oral calcium polystyrene sulfonate for hyperkalemia in CKD patients

Background

Calcium polystyrene sulfonate (CPS) has long been used to treat hyperkalemia in patients with chronic kidney disease (CKD). However, its efficacy and safety profile have not been systematically explored. We investigated the long-term efficacy of oral CPS for treating mild hyperkalemia on an outpatient basis.

Methods

We performed a retrospective analysis of ambulatory CKD patients who were prescribed CPS for > 1 week because of elevated serum potassium levels > 5.0 mmol/L. Patients were divided into four groups according to the length of time that they took a fixed dosage of CPS (Group 1, < 3 months; Group 2, 3–6 months; Group 3, 6–12 months; and Group 4, > 1 year). Response was defined as a decrease in the serum potassium level (> 0.3 mmol/L) after treatment with CPS.

Results

We enrolled a total of 247 adult patients with a basal eGFR level of 30 ± 15 mL/min/1.73 m². All patients took small doses of CPS (8.0 ± 3.6 g/d), and serum potassium decreased in a dose-dependent fashion. Serum potassium of all patients decreased significantly from 5.8 ± 0.3 mmol/L to 4.9 ± 0.7 mmol/L with CPS treatment (P < 0.001). The response rates were 79.9%, 71.4%, 66.7%, and 86.8% in Groups 1, 2, 3, and 4, respectively. No serious adverse effects were reported during CPS administration, though constipation was noted in 19 patients (8%).

Conclusion

Small doses of oral CPS are effective and safe for controlling mild hyperkalemia in CKD patients over a long period of time.

Role of Hyperkalemia in Heart Failure and the Therapeutic Use of Potassium Binders

Hyperkalemia can be a life-threatening disorder, especially for at-risk patients with heart failure, chronic kidney disease, with diabetes, and patients on certain drugs like renin-angiotensin-aldosterone system antagonists and mineralocorticoid receptor antagonists. There are limited therapeutic options available for hyperkalemia, and they have narrow effectiveness because of their unfavorable side effects profile in long-term and high cost utilization requiring inpatient care. Patiromersorbitex calcium and sodium zirconium cyclosilicate are novel potassium-lowering compounds for the treatment and prevention of hyperkalemia in at-risk population. These therapeutic agents have shown encouraging results in early phase II and phase III clinical trials. However, there is need to further study their efficacy and safety in heart failure population in order to establish their clinical use. The focus of this chapter will be to promote better understanding of potassium homeostasis in heart failure patients and the mechanistic overview of novel drugs, with emphasis on heart failure population.

Sodium Zirconium Cyclosilicate (ZS-9): A Novel Agent for the Treatment of Hyperkalemia

Hyperkalemia is a potentially life-threatening electrolyte abnormality that may be caused by select medications, underlying organ dysfunction, or alterations in potassium homeostasis. Treatment for this condition has remained largely unchanged since the release of sodium polystyrene sulfonate (SPS) in 1958. Despite its widespread use, the safety and efficacy of SPS remains controversial. Two novel potassium-binding resins have emerged in recent years. Patiromer was the first of these to receive U.S. Food and Drug Administration approval for the treatment of hyperkalemia in October 2015. A second potassium-binding resin, a zirconium cyclosilicate currently known as ZS-9, may provide yet another alternative to the archetypal treatment with SPS. ZS-9 is an orally administered nonabsorbed inorganic compound that selectively binds potassium ions in vivo. Two phase III multicenter, randomized, placebo-controlled, double-blind trials have evaluated ZS-9 for the treatment of acute hyperkalemia. In this review, we discuss the pharmacology, clinical efficacy, safety, and potential place in therapy of ZS-9 for the enhanced elimination of potassium in the setting of hyperkalemia.

Pharmacodynamics and pharmacokinetics of sodium zirconium cyclosilicate [ZS-9] in the treatment of hyperkalemia

INTRODUCTION

Hyperkalemia is a common electrolyte disorder that arises from dysfunctional homeostatic mechanisms or as a consequence of decreased renal function. Sodium zirconium cyclosilicate (ZS-9) is a potential new therapy for hyperkalemia in both acute and chronic settings.

AREAS COVERED

Here we discuss mechanisms of potassium homeostasis and preclinical and clinical studies that present pharmacokinetics/pharmacodynamics, efficacy and safety profiles of ZS-9.

EXPERT OPINION

ZS-9 has a unique mechanism of action consisting of thermodynamically favorable sequestration of potassium ions, enabling rapid trapping and removal of excess potassium. The potassium lowering action of ZS-9 is predictable and rapid, leading to significant reduction of serum potassium within 1 hour of administration by irreversibly eliminating excess potassium rather than acting via intracellular translocation. Its safety profile, including gastrointestinal events, has been generally similar to that of placebo, with the exception of infrequent but manageable events of peripheral edema and transient hypokalemia. ZS-9 has demonstrated potential for enabling renin-angiotensin-aldosterone system inhibitors in mid-term studies, with long-term studies ongoing.

Potassium-Binding Agents to Facilitate Renin-Angiotensin-Aldosterone System Inhibitor Therapy

OBJECTIVE

To evaluate safety and efficacy data for potassium-binding resins in renin-angiotensin-aldosterone system (RAAS)-associated hyperkalemia.

DATA SOURCES

A search of MEDLINE (EBSCOhost; 1946 to February 2016) was conducted using the terms hyperkalemia, rennin-angiotensin-aldosterone system, angiotensin-converting enzyme inhibitor, angiotensin receptor blocker, aldosterone antagonists, resin, and binder Results were limited to human trials in English language journals. References of identified articles were reviewed to identify other relevant articles.

STUDY SELECTION AND DATA EXTRACTION

Concurrent potassium-binding agents and RAAS inhibitor use literature were reviewed. Inclusion criteria a 2-week minimum therapy duration with hyperkalemia or high-risk patients receiving concurrent RAAS-inhibiting agents. Seven articles met inclusion criteria: 1 retrospective case series for sodium polystyrene sulfonate (SPS), 1 noncontrolled study using patiromer, and 5 randomized, placebo-controlled trials using 3 different agents-2 patiromer, 2 sodium zirconium cyclosilicate (SZC), and 1 cross-linked polyelectrolyte (CLP).

DATA SYNTHESIS

SPS efficacy data are limited to a mean potassium reduction of 1.8 mEq/L in a 14-patient uncontrolled case series. CLP did not reduce hyperkalemia incidence compared with placebo. Patiromer effectively maintained potassium at 0.45 to 0.72 mmol/L lower than placebo while allowing spironolactone dose titration in more patients (91% vs 74%, P = 0.019). SZC also safely and effectively normalized and maintained potassium levels in patients receiving RAAS inhibitors (71%-85% vs 48% for placebo, P < 0.01).

CONCLUSIONS

Currently, the literature does not support SPS and CLP for preventing RAAS inhibitor-associated hyperkalemia. Patiromer and SZC safely and effectively lower serum potassium and prevent hyperkalemia redevelopment in patients receiving RAAS inhibitors for up to 4 and 8 weeks,0 respectively.

Novel Bloodless Potassium Determination Using a Signal-Processed Single-Lead ECG

BACKGROUND

Hyper- and hypokalemia are clinically silent, common in patients with renal or cardiac disease, and are life threatening. A noninvasive, unobtrusive, blood-free method for tracking potassium would be an important clinical advance.

METHODS AND RESULTS

Two groups of hemodialysis patients (development group, n=26; validation group, n=19) underwent high-resolution digital ECG recordings and had 2 to 3 blood tests during dialysis. Using advanced signal processing, we developed a personalized regression model for each patient to noninvasively calculate potassium values during the second and third dialysis sessions using only the processed single-channel ECG. In addition, by analyzing the entire development group's first-visit data, we created a global model for all patients that was validated against subsequent sessions in the development group and in a separate validation group. This global model sought to predict potassium, based on the T wave characteristics, with no blood tests required. For the personalized model, we successfully calculated potassium values with an absolute error of 0.36±0.34 mmol/L (or 10% of the measured blood potassium). For the global model, potassium prediction was also accurate, with an absolute error of 0.44±0.47 mmol/L for the training group (or 11% of the measured blood potassium) and 0.5±0.42 for the validation set (or 12% of the measured blood potassium).

CONCLUSIONS

The signal-processed ECG derived from a single lead can be used to calculate potassium values with clinically meaningful resolution using a strategy that requires no blood tests. This enables a cost-effective, noninvasive, unobtrusive strategy for potassium assessment that can be used during remote monitoring.

Potassium-Binding Agents for the Clinical Management of Hyperkalemia

Use of sodium polystyrene sulfonate (SPS) dominates the long-term treatment of hyperkalemia, but two new agents, sodium zirconium cyclosilicate and the recently FDA-approved patiromer, may offer potential advantages compared with SPS.

Renal Insufficiency in Concert with Renin-angiotensin-aldosterone Inhibition Is a Major Risk Factor for Hyperkalemia Associated with Low-dose Trimethoprim-sulfamethoxazole in Adults

OBJECTIVE

Low-dose trimethoprim-sulfamethoxazole (TMP-SMX) is commonly used to prevent pneumocystis pneumonia in daily practice. Previous reports have shown a relationship between high- or standard-dose of TMP-SMX and hyperkalemia, however it remains unclear whether this is true for low-dose TMP-SMX. In this study we sought to determine the risk factors for hyperkalemia associated with low-dose TMP-SMX.

METHODS

In this retrospective cohort study, 186 consecutive adult patients who received TMP-SMX as prophylaxis for pneumocystis pneumonia from January 2014 to January 2015 were evaluated. Data on the patients' age, gender, baseline estimated glomerular filtration rate (eGFR), baseline serum potassium, maximum serum potassium, duration reaching the maximal serum potassium level, dosage, and concomitant use of angiotensin-converting enzyme inhibitors (ACEi)/angiotensin receptor blockers (ARB), β-blockers, non-steroidal anti-inflammatory drugs and potassium-sparing diuretics were retrospectively collected. Hyperkalemia was defined as a serum potassium level ≥5 mEq/L. Univariate and multivariate analyses were performed.

RESULTS

The median age of the patients was 66 years and 51.1% were men. Hyperkalemia associated with low-dose TMP-SMX was observed in 32 patients (17.2%). The median duration to reach the maximal serum potassium level was 12 days. The multivariate logistic regression analysis identified renal insufficiency to be a major risk factor for hyperkalemia associated with low-dose TMP-SMX (eGFR <60 mL/min/1.73 m(2), adjusted OR 4.62). Moreover, in the subpopulation of patients with renal insufficiency, ACEi/ARB use was considered to be a major risk factor for hyperkalemia (adjusted OR 3.96).

CONCLUSION

Renal insufficiency in concert with ACEi/ARB use is a major risk factor for hyperkalemia induced by low-dose TMP-SMX.

Recent advances in treatment of heart failure

With the total cases and economic burden of heart failure continuing to rise, there is an overwhelming need for novel therapies. Several drugs for heart failure have succeeded in preclinical and early-phase clinical trials, but most of them failed to show the real benefit in pivotal clinical trials. Meanwhile, the US Food and Drug Administration recently approved two promising new drugs to treat heart failure: ivabradine and sacubitril/valsartan. Furthermore, some of the newer agents in testing offer the potential for significant progress in addition to these drugs. Patiromer and zirconium cyclosilicate are attractive agents that are expected to prevent hyperkalemia during renin-angiotensin-aldosterone system inhibition, and serelaxin and urodilatin are promising drugs in the treatment of acute heart failure. Future clinical trials with more appropriate study designs, optimal clinical endpoints, and proper patient selection are mandatory to assess the true efficacy of these attractive compounds in clinical practice.

Pharmacological interventions for the acute management of hyperkalaemia in adults

BACKGROUND

Hyperkalaemia is a potentially life-threatening electrolyte disturbance which may lead to cardiac arrhythmias and death. Renal replacement therapy is known to be effective in treating hyperkalaemia, but safe and effective pharmacological interventions are needed to prevent dialysis or avoid the complications of hyperkalaemia until dialysis is performed.

OBJECTIVES

This review looked at the benefits and harms of pharmacological treatments used in the acute management of hyperkalaemia in adults. This review evaluated the therapies that reduce serum potassium as well as those that prevent complications of hyperkalaemia.

SEARCH METHODS

We searched Cochrane Kidney and Transplant's Specialised Register to 18 August 2015 through contact with the Trials' Search Co-ordinator using search terms relevant to this review.

SELECTION CRITERIA

All randomised controlled trials (RCTs) and quasi-RCTs looking at any pharmacological intervention for the acute management of hyperkalaemia in adults were included in this review. Non-standard study designs such as cross-over studies were also included. Eligible studies enrolled adults (aged 18 years and over) with hyperkalaemia, defined as serum potassium concentration ≥ 4.9 mmol/L, to receive pharmacological therapy to reduce serum potassium or to prevent arrhythmias. Patients with artificially induced hyperkalaemia were excluded from this review.

DATA COLLECTION AND ANALYSIS

All three authors screened titles and abstracts, and data extraction and risk of bias assessment was performed independently by at least two authors. Studies reported in non-English language journals were translated before assessment. Authors were contacted when information about results or study methodology was missing from the original publication. Although we planned to group all studies of a particular pharmacological therapy regardless of administration route or dose for analysis, we were unable to conduct meta-analyses because of the small numbers of studies evaluating any given treatment. For continuous data we reported mean difference (MD) and 95% confidence intervals (CI).

MAIN RESULTS

We included seven studies (241 participants) in this review. Meta-analysis of these seven included studies was not possible due to heterogeneity of the treatments and because many of the studies did not provide sufficient statistical information with their results. Allocation and blinding methodology was poorly described in most studies. No study evaluated the efficacy of pharmacological interventions for preventing clinically relevant outcomes such as mortality and cardiac arrhythmias; however there is evidence that several commonly used therapies effectively reduce serum potassium levels. Salbutamol administered via either nebulizer or metered-dose inhaler (MDI) significantly reduced serum potassium compared with placebo. The peak effect of 10 mg nebulised salbutamol was seen at 120 minutes (MD -1.29 mmol/L, 95% CI -1.64 to -0.94) and at 90 minutes for 20 mg nebulised salbutamol (1 study: MD -1.18 mmol/L, 95% CI -1.54 to -0.82). One study reported 1.2 mg salbutamol via MDI 1.2 mg produced a significant decrease in serum potassium beginning at 10 minutes (MD -0.20 mmol/L, P < 0.05) and a maximal decrease at 60 minutes (MD -0.34 mmol/L, P < 0.0001). Intravenous (IV) and nebulised salbutamol produced comparable effects (2 studies). When compared to other interventions, salbutamol had similar effect to insulin-dextrose (2 studies) but was more effective than bicarbonate at 60 minutes (MD -0.46 mmol/L, 95% CI -0.82 to -0.10; 1 study). Insulin-dextrose was more effective than IV bicarbonate (1 study) and aminophylline (1 study). Insulin-dextrose, bicarbonate and aminophylline were not studied in any placebo-controlled studies. None of the included studies evaluated the effect of IV calcium or potassium binding resins in the treatment of hyperkalaemia.

AUTHORS' CONCLUSIONS

Evidence for the acute pharmacological management of hyperkalaemia is limited, with no clinical studies demonstrating a reduction in adverse patient outcomes. Of the studied agents, salbutamol via any route and IV insulin-dextrose appear to be most effective at reducing serum potassium. There is limited evidence to support the use of other interventions, such as IV sodium bicarbonate or aminophylline. The effectiveness of potassium binding resins and IV calcium salts has not been tested in RCTs and requires further study before firm recommendations for clinical practice can be made.

The importance of intake: a gut feeling

Limiting enteric sodium absorption is an attractive option when renal sodium excretion is disturbed. An effective approach in the gut appears to be inhibition of the electroneutral Na(+)/H(+) exchangers (NHE), in particular NHE3. Recently, fluid retention, blood pressure and target organ injury were limited in rats with cardiorenal syndrome when treated with the NHE3 inhibitor tenapanor. The downside was that the osmotic fecal load leads to watery feces. Tenapanor also induced marked reductions in enteric phosphorus absorption in rats with cardiorenal syndrome on a high phosphorus intake and resulted in marked reductions in renal injury and practically prevented vascular calcification. We have yet to discover the clinical relevance in volume terms and vascular calcifications in patients in relation to the tolerated dose. However, even if the tenapanor-induced reduction in sodium adsorption is limited in humins, combination of tenapanor therapy with diuretics may be an interesting option in selected patients.