Potential New Agents for the Management of Hyperkalemia

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.

Treatment of Mild Hyperkalemia in Hospitalized Patients: An Unnecessary Practice?

Background

Sodium polystyrene sulfonate (SPS) is one of the most commonly used treatments for mild hyperkalemia. Other treatments include insulin, sodium bicarbonate, and salbutamol, which may be given alone or in combination. The results of research examining treatment effectiveness for mild hyperkalemia (e.g., the ability of SPS to achieve normokalemia) thus far have been inconsistent. Given that the effectiveness of treatment for mild hyperkalemia is debatable, new research is needed.

Objective

To determine whether treatment of hospitalized patients with mild hyperkalemia (using SPS or another approach, relative to no treatment) was associated with achievement of normokalemia (serum potassium < 5.1 mmol/L).

Methods

For this retrospective, quasi-experimental study, hospitalized patients with index serum potassium level between 5.1 and 6.4 mmol/L were identified. Post-index serum potassium level within 24 hours was dichotomized (< 5.1 or ≥ 5.1 mmol/L). Pre-index serum creatinine and serum potassium levels were recorded as the average of the first 5 values immediately before the index potassium value. For each patient, treatment was categorized as no treatment, SPS treatment, or other treatment strategy.

Results

Among the 1944 patients included in the analysis, the average age was 66.8 (standard deviation 13.5) years; 605 (31.1%) of the patients were women and 1339 (68.9%) were men. Logistic regression results indicated that patients who were female and/or had higher pre-index serum potassium were less likely to return to normokalemia within 24 hours after the time of the index serum potassium value. Treatment category was not a statistically significant predictor of the achievement of normokalemia. Most patients with mild hyperkalemia (> 74.5% in each treatment category) achieved normokalemia, whether or not they received treatment.

Conclusions

The findings of this study suggest that although follow-up is required for mild hyperkalemia in hospitalized patients, active treatment may be unnecessary.

Sodium Zirconium Cyclosilicate among Individuals with Hyperkalemia: A 12-Month Phase 3 Study

BACKGROUND AND OBJECTIVES

Oral sodium zirconium cyclosilicate (formerly ZS-9) binds and removes potassium via the gastrointestinal tract. Sodium zirconium cyclosilicate-associated restoration and maintenance of normokalemia and adverse events were evaluated in a two-part, open label, phase 3 trial.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In the correction phase, adult outpatients with plasma potassium ≥5.1 mmol/L (i-STAT Point-of-Care) received sodium zirconium cyclosilicate 10 g three times daily for 24-72 hours until normokalemic (potassium =3.5-5.0 mmol/L). Qualifying participants entered the ≤12-month maintenance phase and received sodium zirconium cyclosilicate 5 g once daily titrated to maintain normokalemia without dietary or medication restrictions. Prespecified primary end points were restoration of normal serum potassium values (3.5-5.0 mmol/L) during the correction phase and maintenance of serum potassium ≤5.1 mmol/L during the maintenance phase. Adverse events were assessed throughout.

RESULTS

Of 751 participants, 746 (99%) achieved normokalemia during the correction phase (mean serum potassium =4.8 mmol/L; 95% confidence interval, 4.7 to 4.8) and entered the maintenance phase; 466 (63%) participants completed the 12-month trial. Participants were predominantly white, men, and age ≥65 years old; 74% had an eGFR<60 ml/min per 1.73 m², and 65% used renin-angiotensin-aldosterone system inhibitors. Mean time on sodium zirconium cyclosilicate was 286 days. Mean daily sodium zirconium cyclosilicate dose was 7.2 g (SD=2.6). Over months 3-12, mean serum potassium was 4.7 mmol/L (95% confidence interval, 4.6 to 4.7); mean serum potassium values ≤5.1 and ≤5.5 mmol/L were achieved by 88% and 99% of participants, respectively. Of 483 renin-angiotensin-aldosterone system inhibitor users at baseline, 87% continued or had their dose increased; 11% discontinued. Among 263 renin-angiotensin-aldosterone system inhibitor-naïve participants, 14% initiated renin-angiotensin-aldosterone system inhibitor therapy. Overall, 489 (66%) participants experienced adverse events during the maintenance phase, and 22% experienced a serious adverse event. Of eight (1%) deaths, none were considered related to sodium zirconium cyclosilicate. Nine (1%) and 34 (5%) participants experienced serum potassium <3.0 and 3.0-3.4 mmol/L, respectively.

CONCLUSIONS

After achieving normokalemia, individualized once daily sodium zirconium cyclosilicate was associated with maintenance of normokalemia without substantial renin-angiotensin-aldosterone system inhibitor changes for ≤12 months.

Medical Management of Heart Failure With Reduced Ejection Fraction in Patients With Advanced Renal Disease

Large randomized clinical trials (RCT) supporting guidelines for the management of heart failure with reduced ejection fraction (HFrEF) have typically excluded patients with advanced chronic kidney disease (CKD). Patients with concomitant advanced CKD and HFrEF experience poor cardiovascular outcomes and mortality relative to either disease in isolation and have been shown to consistently receive lower rates of HFrEF guideline-directed medical therapy (GDMT). This review evaluated recent evidence for the use of GDMT in patients with HFrEF and advanced CKD approaching dialysis from RCTs and observational cohorts. The authors also discuss the limitations and challenges inherent in the evidence for GDMT in this population, and offer guidance to clinicians for proper clinical use and future research directions.

Current treatment and unmet needs of hyperkalaemia in the emergency department

Hyperkalaemia is a common electrolyte abnormality and can cause life-threatening cardiac arrhythmia. Even though it is common in patients with diabetes, heart failure, and kidney disease, there is poor consensus over its definition and wide variability in its treatment. Medications used to treat hyperkalaemia in the emergent setting do not have robust efficacy and safety data to guide treatment leading to mismanagement due to poor choice of some agents or inappropriate dosing of others. Moreover, the medications used in the emergent setting are at best temporizing measures, with dialysis being the definitive treatment. New and old k binder therapies provide means to excrete potassium, but their roles are unclear in the emergent setting. Electrocardiograms are the corner stones of hyperkalaemia management; however, recent studies show that they might manifest abnormalities infrequently, even in severe hyperkalaemia, thus questioning their role. With an aging population and a rise in rates of heart and kidney failure, hyperkalaemia is on the rise, and there is a need, now more than ever, to understand the efficacy and safety of the current medications and to develop newer ones.

Safety of potassium-bearing citrate in patients with renal transplantation: A case report

RATIONALE

Urinary lithiasis is one of severe postoperative complications in patients undergoing renal transplantation, possibly leading to anuria, urinary infection, or even acute renal failure. Potassium sodium hydrogen citrate (PSHC), a potassium-bearing citrate, is commonly prescribed to prevent stone formation.

PATIENT CONCERNS

A 25-year-old man (patient 1) and a 31-year-old man (patient 2) receiving renal transplantation for end-stage renal disease (ESRD) were enrolled in this study. They were given 10 g/day of PSHC granules from the ninth day to the 17th day after surgery. Patient 1 presented chest tightness, nausea, muscle weakness, and ascending paralysis on the 10th day. Patient 2 presented weak waves on EGG on the 17th day. Moreover, their serum potassium concentrations (SPCs) were 7.67 and 6.05 mmol/L, respectively.

DIAGNOSIS

Acute hyperkalemia.

INTERVENTIONS

Hemo-filtration was performed for patient 1, while patient 2 received 10% calcium gluconate 10 mL, 5% NaHCO3 125 mL, and 10% glucose 500 mL with the addition of 10 units of insulin through intravenous drip.

OUTCOMES

Their SPCs dropped to the normal range.

LESSONS

Physicians should pay close attentions to potential risks caused by PSHC, and monitor the SPCs to minimize the occurrence of hyperkalemia.

Hyperkalemia in Heart Failure

Disorders of potassium homeostasis can potentiate the already elevated risk of arrhythmia in heart failure. Heart failure patients have a high prevalence of chronic kidney disease, which further heightens the risk of hyperkalemia, especially when renin-angiotensin-aldosterone system inhibitors are used. Acute treatment for hyperkalemia may not be tolerated in the long term. Recent data for patiromer and sodium zirconium cyclosilicate, used to treat and prevent high serum potassium levels on a more chronic basis, have sparked interest in the treatment of hyperkalemia, as well as the potential use of renin-angiotensin-aldosterone system inhibitors in patients who were previously unable to take these drugs or tolerated only low doses. This review discusses the epidemiology, pathophysiology, and outcomes of hyperkalemia in heart failure; provides an overview of traditional and novel ways to approach management of hyperkalemia; and discusses the need for further research to optimally treat heart failure.

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.

Fatal intravenous injection of potassium: Is postmortem biochemistry useful for the diagnosis?

Fatal cases of potassium overdoses have traditionally been considered indemonstrable due postmortem biochemical investigation limits (mainly potassium determination in postmortem serum and vitreous humor). Nevertheless, some authors have expressed a divergent opinion over the years based on the results of their own investigations. In this study, we investigated left vitreous, right vitreous, postmortem serum from peripheral blood, postmortem serum from cardiac blood, urine, pericardial and cerebrospinal fluid potassium concentrations in 21 forensic autopsy cases. One of these was a case of accidental, fatal intravenous potassium injection in a hospitalized patient. The other twenty cases were subjects with various causes of death unrelated to potassium administration and comparable postmortem intervals. Our aim was to assess whether postmortem biochemical investigations performed in several biological samples may be useful in diagnosing exogenous potassium administration. No statistically significant differences were observed between the measured concentrations in the fatal case of potassium intravenous administration and the control cases in any of the tested samples. Potassium concentrations in the investigated case of exogenous potassium injection were within the range of those measured in the control cases, irrespective of the tested biological sample. Our findings corroborate the conclusions of former authors who highlighted that circumstantial evidence provides the greatest diagnostic contribution in situations of suspected potassium poisoning. This is due to the objective limitations demonstrated by postmortem biochemical investigations in such cases, even when potassium measurements are carried out in several biological samples of satisfying quality and within a relatively short postmortem interval.

Patiromer: A Review in Hyperkalaemia

Patiromer (Veltassa(™)) for oral suspension is a sodium-free potassium binder that is approved in the USA for the treatment of hyperkalaemia. In clinical trials, patiromer significantly reduced serum potassium levels from baseline to week 4 in patients with chronic kidney disease (CKD) and mild to severe hyperkalaemia (OPAL-HK), or CKD, mild to moderate hyperkalaemia and type 2 diabetes mellitus (AMETHYST-DN), who were receiving renin-angiotensin-aldosterone system inhibitors (RAASis; drugs that inhibit the renal excretion of potassium). Among patients in OPAL-HK who had moderate to severe hyperkalaemia at baseline and normokalaemia on patiromer and RAASis at week 4, continuing patiromer for a further 8 weeks maintained reductions in potassium levels more effectively than switching to placebo (i.e. withdrawing patiromer); consequently, fewer patiromer than placebo recipients experienced recurrent hyperkalaemia during this period. Furthermore, almost all patiromer (vs. less than half of placebo) recipients were still receiving RAASi therapy at the end of this trial. In AMETHYST-DN, the significant reduction from baseline in serum potassium levels seen at week 4 was sustained for up to 52 weeks. Patiromer was generally well tolerated in these trials, with no treatment-related serious adverse events or deaths. Commonly occurring treatment-related adverse events include mild to moderate constipation and hypomagnesaemia, and there is a low risk of hypokalaemia. In conclusion, oral patiromer is a useful new option for patients with hyperkalaemia.