PEARL-HF: prevention of hyperkalemia in patients with heart failure using a novel polymeric potassium binder, RLY5016

Real-world management of chronic and postprandial hyperkalemia in CKD patients treated with patiromer: a single-center retrospective study

INTRODUCTION

Hyperkalemia, one of the most important electrolyte abnormalities of chronic kidney disease (CKD), often limits the use of renin-angiotensin-aldosterone system inhibitors and can increase in the postprandial period. In this study we report a real-world experience with the new non-adsorbed potassium binder patiromer in stage 3b-4 CKD patients. Moreover, we performed a cross-sectional analysis to evaluate, for the first time, the efficacy of patiromer in the control of postprandial potassium concentrations.

METHODS

We retrospectively collected data of 40 patients at the time of patiromer initiation (T0), and after 2 (T2), 6 (T6) and 12 (T12) months of treatment. For cross sectional analysis, a blood sample was collected 2 h after the main meal for the evaluation of postprandial potassium concentrations.

RESULTS

Eighty-two point five percent of patients (33/40) reached normal potassium concentrations at T2. Serum potassium significantly decreased at T2 compared to T0 (5.13 ± 0.48 vs 5.77 ± 0.41 mmol/L, respectively; p < 0.001) and the reduction remained significant during the follow-up (5.06 ± 0.36 at T6 and 5.77 ± 0.41 at T12; p < 0.001 vs T0). Renin-angiotensin-aldosterone system inhibitors were continued by 93% of patients (27/29). Adverse events were reported in 27.5% of patients and were all mild-to-moderate. Postprandial potassium concentrations did not significantly change compared to fasting state potassium measured at T12 (4.53 ± 0.33 vs 5.06 ± 0.36 mmol/L; p = 0.15).

CONCLUSIONS

In a real-world setting of advanced CKD patients, patiromer is a useful treatment for hyperkalemia, since it significantly reduces serum potassium levels over the long term and is able to maintain potassium concentrations in the normal range even in the post-prandial period.

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.

Sequencing Quadruple Therapy for Heart Failure with Reduced Ejection Fraction: Does It Really Matter?

The conventional sequence of guideline-directed medical therapy (GDMT) initiation in heart failure with reduced ejection fraction (HFrEF) assumes that the effectiveness and tolerability of GDMT agents mirror their order of discovery, which is not true. In this review, the authors discuss flexible GDMT sequencing that should be permitted in special populations, such as patients with bradycardia, chronic kidney disease, or atrial fibrillation. Moreover, the initiation of certain GDMT medications may enable tolerance of other GDMT medications. Most importantly, the achievement of partial doses of all four pillars of GDMT is better than achievement of target dosing of only a couple.

The Efficacy and Safety of Patiromer for Heart Failure Patients: A Systematic Review and Meta-Analysis

PURPOSE

To evaluate the efficacy and safety of patiromer, a novel potassium binder, in reducing the risk of hyperkalemia in patients with heart failure and optimizing their RAASi therapy.

DESIGN

Systematic review and meta-analyses.

METHOD

The authors conducted a systematic search in Pubmed, Embase, Web of Science, and Cochrane Library for randomized controlled trials investigating the efficacy and safety of patiromer in heart failure patients from inception to 31 January 2023 and updated on 25 March 2023. The primary outcome was the association between the reduction of hyperkalemia and patiromer compared with placebo, and the secondary outcome was the association between optimization of RAASi therapy and patiromer.

RESULTS

A total of four randomized controlled trials (n = 1163) were included in the study. Patiromer was able to reduce the risk of hyperkalemia in heart failure patients by 44% (RR 0.56, 95% CI 0.36 to 0.87; I² = 61.9%), improve tolerance to target doses of MRA in patients with heart failure (RR 1.15, 95% CI 1.02 to 1.30; I² = 49.4%), and decrease the proportion of all-cause discontinuation of RAASi (RR 0.49, 95% CI 0.25 to 0.98; I² = 48.4%). However, patiromer therapy was associated with an increased risk of hypokalemia (RR 1.51, 95% CI 1.07 to 2.12; I² = 0%), while no other statistically significant adverse events were observed.

CONCLUSION

Patiromer appears to have a considerable effect on reducing the incidence of hyperkalemia in heart failure patients and on optimizing the therapy of RAASi in those patients.

Comparison of Patiromer to Sodium Polystyrene Sulfonate in Acute Hyperkalemia

Background: Patiromer and sodium polystyrene sulfonate (SPS) are cation-exchangers approved for the treatment of chronic hyperkalemia. Data regarding their efficacy acutely is lacking. Despite this, both drugs are frequently used in the emergent setting. Objective: The purpose of this study was to compare the potassium reduction of patiromer to SPS within 6 to 24 hours following a single dose. Methods: This retrospective quality improvement project included hyperkalemic patients receiving 1 dose of patiromer or SPS and had a second potassium level drawn in 6 to 24 hours. Doses of 8.4 g of patiromer and 15 g of SPS were considered "low dose" while 16.8 g of patiromer and 30 g of SPS were considered "high dose." The presence of a dose-response relationship was assessed through a linear regression analysis. Results: Mean (SD) potassium reduction was higher in SPS than patiromer [0.76 (0.63) mEq/L vs 0.32 (0.65) mEq/L, (P = .001)]. A dose response relationship was not demonstrated in low versus high dose groups [-0.21 (0.14), P = .13] and CKD, ESRD, and renal transplant patients when compared to patients with normal renal function [0.11 (0.17), P = .51, -0.07 (0.19), P = -0.07 (0.19), P = .73, and -0.10 (0.22), P = .65]. Conclusions: This study suggests a clinically significant reduction in potassium with SPS compared to patiromer. Although SPS was successful in demonstrating this outcome, due to well-documented adverse reactions in the literature and a time to onset of 6 hours, it cannot be recommended for use in acute hyperkalemia either.

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.

Patiromer in a Patient with Severe Hyperkalemia on Incremental Hemodialysis with 1 Session per Week: A Case Report and Literature Review

Hyperkalemia is common in patients with ESRD, undergoing hemodialysis (HD), and is associated with an increase in hospitalization and mortality. Residual kidney function in long-term dialysis patients is associated with lower morbidity and mortality in HD patients. Although the 2015 National Kidney Foundation-Kidney Disease Outcomes Quality Initiate (NKD-KDOQI) guidelines allow the reduction in the weekly HD dose for patients with a residual kidney urea clearance (Kur) >3 mL/min/1.73 m², very few centers adjust the dialysis dose based on these criteria. In our center, the pattern of incremental hemodialysis (iHD) with once-a-week schedule (1 HD/W) has been an option for a group of patients showing very good results. This pattern is maintained as long as residual diuresis is >1,000 mL/24 h, Kur is >4 mL/min, and there is no presence of edema or volume overload, as well as no analytical parameters persistently outside the advisable range (serum phosphorus >6 mg/dL or potassium [K⁺] >6.5 mmol/L). Management of hyperkalemia in HD patients includes reduction of dietary intake, dosing of medications that contribute to hyperkalemia, and use of cation-exchange resins such as calcium or sodium polystyrene sulfonate. Two newer potassium binders, patiromer sorbitex calcium and sodium zirconium cyclosilicate, have been safely used for potassium imbalance treatment in patients with ESRD in HD with a conventional regimen of thrice weekly, but has not yet been studied in 1 HD/W schedules. We present the case of a 76-year-old woman in iHD (1 HD/W) treated with patiromer for severe HK and describe her clinical characteristics and outcomes. In addition, we review the corresponding literature. Based on these data, it can be anticipated that the use of patiromer may overcome the risk of hyperkalemia in patients with incident ESRD treated with less-frequent HD regimens.

Novelties in Therapy of Chronic Heart Failure

In recent decades, considerable advances have been made in the treatment of heart failure. The main target of heart failure therapy is the inhibition of the sympathetic nervous system and renin-angiotensin-aldosterone system. The angiotensin receptor blockers represent a breakthrough in the treatment of heart failure with a demonstrated effect on reduction of cardiovascular events. However, new perspectives derive from latest drugs developed for diabetes, iron deficiency, and hyperkalemia. New frontiers are also opened to the development of neurohormonal therapies, antagonists of inflammatory mediators, inotropic agents, and cell-based treatments.

Hyperkalemia in heart failure: Foe or friend?

Hyperkalemia is a frequent and sometimes life‐threatening condition that may be associated with arrhythmia and cardiac dysfunction in patients with heart failure (HF). High potassium levels in HF represent both a direct risk for cardiovascular complication and an indirect biomarker of the severity of the underlying disease, reflecting neurohormonal activation and renal dysfunction. Evaluating the prevalence and significance of hyperkalemia in HF patients is essential for optimizing the use of potassium sparing agents, such the renin–angiotensin–aldosterone system inhibitors (RAASi) or angiotensin receptor‐neprilysin inhibitors and mineralocorticoid receptor antagonists, which represent a well‐established cornerstone and life‐saving therapy. In this review we discuss recent findings and current concepts related to the epidemiology, pathological mechanisms and implications of hyperkalemia, as well as novel therapeutic approaches to counteract it in patients with HF. The balance between optimizing life‐saving potassium sparing medication and minimizing hyperkalemia‐associated risk is much needed in patients with HF. Although older potassium‐binding agents are associated with serious adverse events, novel potassium‐binding drugs are effective in lowering potassium levels and are generally well tolerated. Novel potassium‐binding drugs, such as patiromer and sodium zirconium cyclosilicate, may help to optimize therapy in HF and achieve guideline‐recommended doses. Hyperkalemia is common in HF patients and is associated with a poorer prognosis and an increased risk of cardiovascular complications: Contrariwise, “moderate” potassium levels go with a better prognosis, while the emergence of new drugs, potassium binders, could allow target doses of RAASi to be achieved.

Pivotal clinical trials, meta-analyses and current guidelines in the treatment of hyperkalemia

Hyperkalemia (HK) is the most common electrolyte disturbance observed in patients with advanced stages of chronic kidney disease (CKD), is a potentially life-threatening clinical condition due to an increased risk of fatal arrhythmias, and strongly impacts the quality of life and prognosis of CKD patients. Moreover, while renin–angiotensin–aldosterone system inhibitors (RAASIs) represent the most cardio-nephro-protective drugs used in clinical practice, the treatment with these drugs per se increases serum potassium (sK) values, particularly when heart failure and diabetes mellitus coexist. In fact, the onset or recurrence of HK is frequently associated with not starting, down-titrating or withdrawing RAASIs, and is an indication to begin renal replacement treatment in end-stage renal disease. Current strategies aimed at preventing and treating chronic HK are still unsatisfactory, as evidenced by the relatively high prevalence of HK also in patients under stable nephrology care, and even in the ideal setting of randomized clinical trials. Indeed, dietary potassium restriction, the use of sodium bicarbonate or diuretics, the withdrawal or down-titration of RAASIs, or the administration of old potassium binders, namely sodium polystyrene sulphonate and calcium polystyrene sulphonate, have limited efficacy and are poorly tolerated; therefore, these strategies are not suitable for long-term control of sK. As such, there is an important unmet need for novel therapeutic options for the chronic management of patients at risk for HK. The development of new potassium binders may change the treatment landscape in the near future. This review summarizes the current evidence on the treatment of chronic HK in cardio-renal patients.

A new area for the management of hyperkalaemia with potassium binders: clinical use in nephrology

Chronic kidney disease (CKD) patients and more so CKD patients treated with renin-angiotensin-aldosterone system inhibitors (RAASi) are prone to experience hyperkalaemia, a condition associated with an increased risk of death. This represents a true dilemma in daily practice since RAASi are the cornerstones of nephroprotective and cardioprotective strategies in CKD patients, as well as in hypertensive patients with or without CKD. The recent availability in the USA and EU of the potassium-binding resin Patiromer, together with sodium zirconium cyclosilicate (SZC), which was more recently approved in the EU and the US, may lead to a paradigm shift both in the treatment of hyperkalaemia and in enabling RAASi maintenance. Whether potassium normalization, potentially combined with a RAASi maintenance strategy, may translate into improved cardiovascular and renal outcomes needs be tested prospectively.

Chronic hyperkalemia in non-dialysis CKD: controversial issues in nephrology practice

Chronic hyperkalemia is a major complication of chronic kidney disease (CKD) that occurs frequently, heralds poor prognosis, and necessitates careful management by the nephrologist. Current strategies aimed at prevention and treatment of hyperkalemia are still suboptimal, as evidenced by the relatively high prevalence of hyperkalemia in patients under stable nephrology care, and even in the ideal setting of randomized trials where best treatment and monitoring are mandatory. The aim of this review was to identify and discuss a range of unresolved issues related to the management of chronic hyperkalemia in non-dialysis CKD. The following topics of clinical interest were addressed: diagnosis, relationship with main comorbidities of CKD, therapy with inhibitors of the renin-angiotensin-aldosterone system, efficacy of current dietary and pharmacological treatment, and the potential role of the new generation of potassium binders. Opinion-based answers are provided for each of these controversial issues.

Serum potassium and adverse outcomes across the range of kidney function: a CKD Prognosis Consortium meta-analysis

Aims

Both hypo- and hyperkalaemia can have immediate deleterious physiological effects, and less is known about long-term risks. The objective was to determine the risks of all-cause mortality, cardiovascular mortality, and end-stage renal disease associated with potassium levels across the range of kidney function and evaluate for consistency across cohorts in a global consortium.

Methods and results

We performed an individual-level data meta-analysis of 27 international cohorts [10 general population, 7 high cardiovascular risk, and 10 chronic kidney disease (CKD)] in the CKD Prognosis Consortium. We used Cox regression followed by random-effects meta-analysis to assess the relationship between baseline potassium and adverse outcomes, adjusted for demographic and clinical characteristics, overall and across strata of estimated glomerular filtration rate (eGFR) and albuminuria. We included 1 217 986 participants followed up for a mean of 6.9 years. The average age was 55 ± 16 years, average eGFR was 83 ± 23 mL/min/1.73 m2, and 17% had moderate- to-severe increased albuminuria levels. The mean baseline potassium was 4.2 ± 0.4 mmol/L. The risk of serum potassium of >5.5 mmol/L was related to lower eGFR and higher albuminuria. The risk relationship between potassium levels and adverse outcomes was U-shaped, with the lowest risk at serum potassium of 4-4.5 mmol/L. Compared with a reference of 4.2 mmol/L, the adjusted hazard ratio for all-cause mortality was 1.22 [95% confidence interval (CI) 1.15-1.29] at 5.5 mmol/L and 1.49 (95% CI 1.26-1.76) at 3.0 mmol/L. Risks were similar by eGFR, albuminuria, renin-angiotensin-aldosterone system inhibitor use, and across cohorts.

Conclusions

Outpatient potassium levels both above and below the normal range are consistently associated with adverse outcomes, with similar risk relationships across eGFR and albuminuria.

Potassium homeostasis in health and disease: A scientific workshop cosponsored by the National Kidney Foundation and the American Society of Hypertension

While much emphasis, and some controversy, centers on recommendations for sodium intake, there has been considerably less interest in recommendations for dietary potassium intake, in both the general population and patients with medical conditions, particularly acute and chronic kidney disease. Physiology literature and cohort studies have noted that the relative balance in sodium and potassium intakes is an important determinant of many of the sodium-related outcomes. A noteworthy characteristic of potassium in clinical medicine is the extreme concern shared by many practitioners when confronted by a patient with hyperkalemia. Fear of this often asymptomatic finding limits enthusiasm for recommending potassium intake and often limits the use of renin-angiotensin-aldosterone system blockers in patients with heart failure and chronic kidney diseases. New agents for managing hyperkalemia may alter the long-term management of heart failure and the hypertension, proteinuria, and further function loss in chronic kidney diseases. In this jointly sponsored effort between the American Society of Hypertension and the National Kidney Foundation, 3 panels of researchers and practitioners from various disciplines discussed and summarized current understanding of the role of potassium in health and disease, focusing on cardiovascular, nutritional, and kidney considerations associated with both hypo- and hyperkalemia.

Potassium Homeostasis in Health and Disease: A Scientific Workshop Cosponsored by the National Kidney Foundation and the American Society of Hypertension

While much emphasis, and some controversy, centers on recommendations for sodium intake, there has been considerably less interest in recommendations for dietary potassium intake, in both the general population and patients with medical conditions, particularly acute and chronic kidney disease. Physiology literature and cohort studies have noted that the relative balance in sodium and potassium intakes is an important determinant of many of the sodium-related outcomes. A noteworthy characteristic of potassium in clinical medicine is the extreme concern shared by many practitioners when confronted by a patient with hyperkalemia. Fear of this often asymptomatic finding limits enthusiasm for recommending potassium intake and often limits the use of renin-angiotensin-aldosterone system blockers in patients with heart failure and chronic kidney diseases. New agents for managing hyperkalemia may alter the long-term management of heart failure and the hypertension, proteinuria, and further function loss in chronic kidney diseases. In this jointly sponsored effort between the American Society of Hypertension and the National Kidney Foundation, 3 panels of researchers and practitioners from various disciplines discussed and summarized current understanding of the role of potassium in health and disease, focusing on cardiovascular, nutritional, and kidney considerations associated with both hypo- and hyperkalemia.

Updates in hyperkalemia: Outcomes and therapeutic strategies

Hyperkalemia is a frequent clinical abnormality in patients with chronic kidney disease, and it is associated with higher risk of mortality and malignant arrhythmias. Severe hyperkalemia is a medical emergency, which requires immediate therapies, followed by interventions aimed at preventing its recurrence. Current treatment paradigms for chronic hyperkalemia management are focused on eliminating predisposing factors, such as high potassium intake in diets or supplements, and the use of medications known to raise potassium level. Among the latter, inhibitors of the renin-angiotensin aldosterone system are some of the most commonly involved medications, and their discontinuation is often the first step taken by clinicians to prevent the recurrence of hyperkalemia. While this strategy is usually successful, it also deprives patients of the recognized benefits of this class, such as their renoprotective effects. The development of novel potassium binders has ushered in a new era of hyperkalemia management, with a focus on chronic therapy while maintaining the use of beneficial, but hyperkalemia-inducing medications such as renin-angiotensin aldosterone system inhibitors. This review article examines the incidence and clinical consequences of hyperkalemia, and its various treatment options, with special emphasis on novel therapeutic agents and the potential benefits of their application.

Efficacy and Safety of Patiromer in Hyperkalemia: A Systematic Review and Meta-Analysis

BACKGROUND

Patients at the highest risk of hyperkalemia are those with chronic kidney disease (CKD) stages 3 and 4.

OBJECTIVE

To evaluate the efficacy and safety of patiromer in hyperkalemia in patients with heart failure or CKD.

METHODS

The Cochrane Renal Group's Specialized Register was searched through contact with the Trials' Search Coordinator. We aimed at including randomized controlled trials with patiromer in patients with developed or risks of developing hyperkalemia, comparing against an active comparator or placebo. Three studies matched our inclusion and exclusion criteria, which we included in the meta-analysis. All-cause mortality, reduction in hospitalization, episodes of hypokalemia or hyperkalemia, and cardiovascular and gastrointestinal adverse events during the treatment period were our primary outcomes. Serial change in serum potassium (K⁺) until end of treatment or follow-up during the trial period and all other reported adverse reactions during the treatment period were our secondary outcomes. Meta-analysis (RevMan version 5.3.5) and descriptive statistics were used.

RESULTS

There was a non-significant improvement in all-cause mortality and serious cardiovascular events with patiromer than placebo. Hospitalization data were unavailable. Although serious gastrointestinal events were more common with placebo, there was a significant reduction ( P = .02) in the risk of non-serious gastrointestinal events with placebo. Patiromer lowered serum K⁺ more than placebo, and there were more patients developing hyperkalemia with placebo. High-dose patiromer was associated with better efficacy in some parameters but with more adverse events.

CONCLUSION

Although patiromer seems promising, more trials with active comparator are essential to finalize its indication and use in hyperkalemia.

Effect of Patiromer on Urinary Ion Excretion in Healthy Adults

BACKGROUND AND OBJECTIVES

Patiromer is a nonabsorbed potassium-binding polymer that uses calcium as the counterexchange ion. The calcium released with potassium binding has the potential to be absorbed or bind phosphate. Because binding is not specific for potassium, patiromer can bind other cations. Here, we evaluate the effect of patiromer on urine ion excretion in healthy adults, which reflects gastrointestinal ion absorption.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We analyzed the effect of patiromer on urine potassium, sodium, magnesium, calcium, and phosphate in two studies. Healthy adults on controlled diets in a clinical research unit were given patiromer up to 50.4 g/d divided three times a day for 8 days (dose-finding study) or 25.2 g/d in a crossover design as daily or divided (two or three times a day) doses for 18 days (dosing regimen study). On the basis of 24-hour collections, urinary ion excretion during the baseline period (days 5-11) was compared with that during the treatment period (days 13-19; dose-finding study), and the last 4 days of each period were compared across regimens (dosing regimen study).

RESULTS

In the dose-finding study, patiromer induced a dose-dependent decrease in urine potassium, urine magnesium, and urine sodium (P<0.01 for each). Patiromer at 25.2 g/d decreased urine potassium (mean±SD) by 1140±316 mg/d, urine magnesium by 45±1 mg/d, and urine sodium by 225±145 mg/d. Urine calcium increased in a dose-dependent manner, and urine phosphate decreased in parallel (both P<0.01). Patiromer at 25.2 g/d increased urine calcium by 73±23 mg/d and decreased urine phosphate by 64±40 mg/d. Urine potassium, urine sodium, and urine magnesium were unaffected by dosing regimen, whereas the increase in urine calcium was significantly lower with daily compared with three times a day dosing (P=0.01). Urine phosphate also decreased less with daily compared with two or three times a day dosing (P<0.05).

CONCLUSIONS

In healthy adults, patiromer reduces urine potassium, urine sodium, urine magnesium, and urine phosphate, while modestly increasing urine calcium. Compared with divided dosing, administration of patiromer once daily provides equivalent reductions in urine potassium, urine sodium, and urine magnesium, with less effect on urine calcium and urine phosphate.

Emergency management of severe hyperkalemia: Guideline for best practice and opportunities for the future

Hyperkalemia is a common electrolyte disorder, especially in chronic kidney disease, diabetes mellitus, or heart failure. Hyperkalemia can lead to potentially fatal cardiac dysrhythmias, and it is associated with increased mortality. Determining whether emergency therapy is warranted is largely based on subjective clinical judgment. The Investigator Network Initiative Cardiovascular and Renal Clinical Trialists (INI-CRCT) aimed to evaluate the current knowledge pertaining to the emergency treatment of hyperkalemia. The INI-CRCT developed a treatment algorithm reflecting expert opinion of best practices in the context of current evidence, identified gaps in knowledge, and set priorities for future research. We searched PubMed (to August 4, 2015) for consensus guidelines, reviews, randomized clinical trials, and observational studies, limited to English language but not by publication date. Treatment approaches are based on small studies, anecdotal experience, and traditional practice patterns. The safety and real-world effectiveness of standard therapies remain unproven. Prospective research is needed and should include studies to better characterize the population, define the serum potassium thresholds where life-threatening arrhythmias are imminent, assess the potassium and electrocardiogram response to standard interventions. Randomized, controlled trials are needed to test the safety and efficacy of new potassium binders for the emergency treatment of severe hyperkalemia in hemodynamically stable patients. Existing emergency treatments for severe hyperkalemia are not supported by a compelling body of evidence, and they are used inconsistently across institutions, with potentially significant associated side effects. Further research is needed to fill knowledge gaps, and definitive clinical trials are needed to better define optimal management strategies, and ultimately to improve outcomes in these patients.

Current and future treatment options for managing hyperkalemia

Hyperkalemia is associated with life-threatening cardiac arrhythmias and increased mortality. Hyperkalemia is most often observed in patients with chronic kidney disease and/or in those with congestive heart failure being treated with drugs that limit renal potassium excretion, especially drugs that inhibit the renin-angiotensin-aldosterone system. Treatment of hyperkalemia may be either acute, as needed during rapid changes in serum potassium, which are associated with cardiac arrhythmia, or chronic, which stabilizes serum potassium levels and limits the development of life-threatening arrhythmias. There are a number of both acute and chronic treatments available for the treatment of hyperkalemia, but some are limited by complex administration requirements and/or serious side effects. Hyperkalemia remains a vexing problem for clinicians, particularly in the care of patients with chronic kidney disease and cardiovascular disease.

Potential New Agents for the Management of Hyperkalemia

Hyperkalemia is a common electrolyte disturbance with multiple potential etiologies. It is usually observed in the setting of reduced renal function. Mild to moderate hyperkalemia is usually asymptomatic, but is associated with poor prognosis. When severe, hyperkalemia may cause serious acute cardiac arrhythmias and conduction abnormalities, and may result in sudden death. The rising prevalence of conditions associated with hyperkalemia (heart failure, chronic kidney disease, and diabetes) and broad use of renin-angiotensin-aldosterone system (RAAS) inhibitors and mineralocorticoid receptor antagonists (MRAs), which improve patient outcomes but increase the risk of hyperkalemia, have led to a significant rise in hyperkalemia-related hospitalizations and deaths. Current non-invasive therapies for hyperkalemia either do not remove excess potassium or have poor efficacy and tolerability. There is a clear need for safer, more effective potassium-lowering therapies suitable for both acute and chronic settings. Patiromer sorbitex calcium and sodium zirconium cyclosilicate (ZS-9) are two new potassium-lowering compounds currently in development. Although they have not yet been approved by the US FDA, both have demonstrated efficacy and safety in recent trials. Patiromer sorbitex calcium is a polymer resin and sorbitol complex that binds potassium in exchange for calcium; ZS-9, a non-absorbed, highly selective inorganic cation exchanger, traps potassium in exchange for sodium and hydrogen. This review discusses the merits of both novel drugs and how they may help optimize the future management of patients with hyperkalemia.

Patiromer: a clinical review

IMPORTANCE

Patiromer FOS (for oral suspension), formerly known as RLY5016, is pending FDA approval for the treatment of hyperkalemia. Once approved, patiromer, as well as a second agent known as sodium zirconium cyclosilicate (ZS-9), will be among the new therapeutic options available to treat hyperkalemia in over 50 years.

OBJECTIVE

The primary objective of this review is to analyze the efficacy and safety of patiromer to treat hyperkalemia and compare its pharmacokinetics to currently available sodium polystyrene sulfonate (SPS) therapy. Patiromer was studied in patients with chronic kidney disease and/or heart failure for both acute and chronic therapy.

EVIDENCE REVIEW

Studies of patiromer were obtained via a literature search of PubMed database and Google Scholar (2000 to the present) using 'patiromer', 'RLY5016', and 'hyperkalemia management' as keywords. Additional references were identified from fda.gov, clinicaltrials.gov, and the pharmaceutical manufacturer, Relypsa Inc.

FINDINGS

Three published clinical trials, ten posters, one clinical trial commentary, three editorials and one oral presentation were obtained. The materials discussed three main clinical trials (PEARL-HF, OPAL-HK and AMETHYST-DN) and examined the safety and efficacy of patiromer in patients with hyperkalemia or at risk for hyperkalemia who have chronic kidney disease (CKD), type 2 diabetes mellitus (T2DM), hypertension and/or heart failure (HF) while receiving renin-angiotensin-aldosterone system inhibitors (RAASis). All three studies achieved their primary endpoints and reduced serum potassium. The PEARL-HF study increased the proportion of patients able to titrate their spironolactone dose from 25 mg/day to 50 mg/day in patients with normokalemia who had a history of hyperkalemia or an estimated glomerular filtration rate of <60 mL/min. The OPAL-HK study allowed patients receiving patiromer to remain on their RAASi therapy. The AMETHYST-DN study demonstrated that patiromer reduced and maintained mean serum potassium ≤5.0 mEq/L for up to 1 year, with a low rate of hypokalemia. Adverse events (AEs) were similar between studies. The most commonly reported adverse event was constipation.

CONCLUSIONS AND RELEVANCE

Patiromer is effective in decreasing serum potassium, preventing recurrence of hyperkalemia, and reducing RAASi discontinuation. Compared to current SPS therapy, patiromer may be the preferred option to treat hyperkalemia, once approved. Patiromer is well tolerated and is not associated with serious AEs.

Management of Hyperkalemia: An Update for the Internist

Hyperkalemia is a clinically important electrolyte abnormality that occurs most commonly in patients with chronic kidney disease. Due to its propensity to induce electrophysiological disturbances, severe hyperkalemia is considered a medical emergency. The management of acute and chronic hyperkalemia can be achieved through the implementation of various interventions, one of which is the elimination of medications that can raise serum potassium levels. Because many such medications (especially inhibitors of the renin-angiotensin aldosterone system) have shown beneficial effects in patients with cardiovascular and renal disease, their discontinuation for reasons of hyperkalemia represent an undesirable clinical compromise. The emergence of 2 new potassium-binding medications for acute and chronic therapy of hyperkalemia may soon allow the continued use of medications such as renin-angiotensin-aldosterone system inhibitors even in patients who are prone to hyperkalemia. This review article provides an overview of the physiology and the pathophysiology of potassium metabolism and hyperkalemia, the epidemiology of hyperkalemia, and its acute and chronic management. We discuss in detail emerging data about new potassium-lowering therapies, and their potential future role 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.

Effect of patiromer on reducing serum potassium and preventing recurrent hyperkalaemia in patients with heart failure and chronic kidney disease on RAAS inhibitors

AIMS

We evaluated the effects of patiromer, a potassium (K(+))-binding polymer, in a pre-specified analysis of hyperkalaemic patients with heart failure (HF) in the OPAL-HK trial.

METHODS AND RESULTS

Chronic kidney disease (CKD) patients on renin-angiotensin-aldosterone system inhibitors (RAASi) with serum K(+) levels ≥5.1 mEq/L to <6.5 mEq/L (n = 243) received patiromer (4.2 g or 8.4 g BID initially) for 4 weeks (initial treatment phase); the primary efficacy endpoint was mean change in serum K(+) from baseline to week 4. Eligible patients (those with baseline K(+) ≥5.5 mEq/L to <6.5 mEq/L and levels ≥3.8 mEq/L to <5.1 mEq/L at the end of week 4) entered an 8-week randomized withdrawal phase and were randomly assigned to continue patiromer or switch to placebo; the primary efficacy endpoint was the between-group difference in median change in the serum K(+) over the first 4 weeks of that phase. One hundred and two patients (42%) had heart failure (HF). The mean [± standard error (SE)] change in serum K(+) from baseline to week 4 was -1.06 ± 0.05 mEq/L [95% confidence interval (CI), -1.16,-0.95; P < 0.001]; 76% (95% CI, 69,84) achieved serum K(+), 3.8 mEq/L to <5.1 mEq/L. In the randomized withdrawal phase, the median increase in serum K(+) from baseline of that phase was greater with placebo (n = 22) than patiromer (n = 27) (P < 0.001); recurrent hyperkalaemia (serum K(+), ≥5.5 mEq/L) occurred in 52% on placebo and 8% on patiromer (P < 0.001). Mild-to-moderate constipation was the most common adverse event (11%); hypokalaemia occurred in 3%.

CONCLUSION

In patients with CKD and HF who were hyperkalaemic on RAASi, patiromer was well tolerated, decreased serum K(+), and, compared with placebo, reduced recurrent hyperkalaemia.

Patiromer induces rapid and sustained potassium lowering in patients with chronic kidney disease and hyperkalemia

Patients with chronic kidney disease (CKD) have a high risk of hyperkalemia, which increases mortality and can lead to renin–angiotensin–aldosterone system inhibitor (RAASi) dose reduction or discontinuation. Patiromer, a nonabsorbed potassium binder, has been shown to normalize serum potassium in patients with CKD and hyperkalemia on RAASi. Here, patiromer's onset of action was determined in patients with CKD and hyperkalemia taking at least one RAASi. After a 3-day potassium- and sodium-restricted diet in an inpatient research unit, those with sustained hyperkalemia (serum potassium 5.5 – under 6.5 mEq/l) received patiromer 8.4 g/dose with morning and evening meals for a total of four doses. Serum potassium was assessed at baseline (0 h), 4 h postdose, then every 2–4 h to 48 h, at 58 h, and during outpatient follow-up. Mean baseline serum potassium was 5.93 mEq/l and was significantly reduced by 7 h after the first dose and at all subsequent times through 48 h. Significantly, mean serum potassium under 5.5 mEq/l was achieved within 20 h. At 48 h (14 h after last dose), there was a significant mean reduction of 0.75 mEq/l. Serum potassium did not increase before the next dose or for 24 h after the last dose. Patiromer was well tolerated, without serious adverse events and no withdrawals. The most common gastrointestinal adverse event was mild constipation in two patients. No hypokalemia (serum potassium under 3.5 mEq/l) was observed. Thus, patiromer induced an early and sustained reduction in serum potassium and was well tolerated in patients with CKD and sustained hyperkalemia on RAASis.

Patiromer in patients with kidney disease and hyperkalemia receiving RAAS inhibitors

BACKGROUND

Hyperkalemia increases the risk of death and limits the use of inhibitors of the renin-angiotensin-aldosterone system (RAAS) in high-risk patients. We assessed the safety and efficacy of patiromer, a nonabsorbed potassium binder, in a multicenter, prospective trial.

METHODS

Patients with chronic kidney disease who were receiving RAAS inhibitors and who had serum potassium levels of 5.1 to less than 6.5 mmol per liter received patiromer (at an initial dose of 4.2 g or 8.4 g twice a day) for 4 weeks (initial treatment phase); the primary efficacy end point was the mean change in the serum potassium level from baseline to week 4. Eligible patients at the end of week 4 (those with a baseline potassium level of 5.5 to <6.5 mmol per liter in whom the level decreased to 3.8 to <5.1 mmol per liter) entered an 8-week randomized withdrawal phase in which they were randomly assigned to continue patiromer or switch to placebo; the primary efficacy end point was the between-group difference in the median change in the serum potassium level over the first 4 weeks of that phase.

RESULTS

In the initial treatment phase, among 237 patients receiving patiromer who had at least one potassium measurement at a scheduled visit after day 3, the mean (±SE) change in the serum potassium level was -1.01±0.03 mmol per liter (P<0.001). At week 4, 76% (95% confidence interval, 70 to 81) of the patients had reached the target potassium level (3.8 to <5.1 mmol per liter). Subsequently, 107 patients were randomly assigned to patiromer (55 patients) or placebo (52 patients) for the randomized withdrawal phase. The median increase in the potassium level from baseline of that phase was greater with placebo than with patiromer (P<0.001); a recurrence of hyperkalemia (potassium level, ≥5.5 mmol per liter) occurred in 60% of the patients in the placebo group as compared with 15% in the patiromer group through week 8 (P<0.001). Mild-to-moderate constipation was the most common adverse event (in 11% of the patients); hypokalemia occurred in 3%.

CONCLUSIONS

In patients with chronic kidney disease who were receiving RAAS inhibitors and who had hyperkalemia, patiromer treatment was associated with a decrease in serum potassium levels and, as compared with placebo, a reduction in the recurrence of hyperkalemia. (Funded by Relypsa; OPAL-HK ClinicalTrials.gov number, NCT01810939.).

Thick ascending limb of the loop of Henle

The thick ascending limb occupies a central anatomic and functional position in human renal physiology, with critical roles in the defense of the extracellular fluid volume, the urinary concentrating mechanism, calcium and magnesium homeostasis, bicarbonate and ammonium homeostasis, and urinary protein composition. The last decade has witnessed tremendous progress in the understanding of the molecular physiology and pathophysiology of this nephron segment. These advances are the subject of this review, with emphasis on particularly recent developments.

Aldosterone and the kidney: a rapidly moving frontier (an update)

Beyond the classical effect of aldosterone on sodium reabsorption in the distal nephron, the spectrum of aldosterone-induced effects on the kidney (and the cardiovascular system) continues to expand at a rapid pace. Blockade of this system has become an attractive target for intervention. Major contributions have been reported in the past 2-3 years. By necessity this brief summary addresses only some of the emerging issues of nephrological relevance. In this fast moving field, we try to give a concise discussion of papers with potential nephrological relevance in the past 2-3 years.

Mineralocorticoid receptor blockade-a novel approach to fight hyperkalaemia in chronic kidney disease

Hyperkalaemia continues to be a major hazard of mineralocorticoid receptor blockade in an effort to retard the progression of chronic kidney disease (CKD). In cardiac patients on mineralocorticoid receptor blockade, RLY-5016 which captures K⁺ in the colon has been effective in reducing the risk of hyperkalaemia. This compound might be useful in CKD as well.

Vascular calcification--is aldosterone a culprit?

In chronic kidney disease (CKD), increased plasma phosphate concentrations cause vascular calcification which substantially contribute to cardiovascular events and increased mortality of CKD patients. Similar to CKD patients, klotho-hypomorphic mice (kl/kl) also suffer from excessive vascular calcification leading to growth deficit, rapid ageing and early death. The hyperphosphataemia of kl/kl mice results from excessive formation of 1,25(OH)2D3 causing excessive intestinal phosphate absorption. Further, kl/kl mice further suffer from hyperaldosteronism and compelling evidence points to an active role of mineralocorticoids in triggering osteoinductive programmes in the vasculature, thus further contributing to the development of vascular calcification. Conversely, in kl/kl mice, the mineralocorticoid receptor antagonist spironolactone decreased the vascular osteoinductive processes and reversed the excessive expression of osteogenic programmes, i.e. type III sodium-dependent phosphate transporter Pit1, tumour necrosis factor α (Tnfα), transcription factors Msx2, Cbfa1/Runx2 and osterix as well as alkaline phosphatase (Alp). In human aortic vascular smooth muscle cells (HAoSMCs), aldosterone alone similarly triggered an 'osteogenic' programme, thus increasing PIT1, TNFα, MSX2, CBFA1/RUNX2 and ALP expression as well as ALP activity and potentiated the effects of phosphate treatment. These effects were again reversed by spironolactone and in addition by PIT1 silencing. The above observations reveal that the severe vascular calcification is not only the result of high plasma phosphate concentrations, but also promoted by aldosterone-driven osteoinductive signalling. Future studies in CKD patients will be required to define the role of aldosterone and the potential impact of its inhibition by spironolactone in the pathophysiology of vascular calcification.