Mechanism of Action and Pharmacology of Patiromer, a Nonabsorbed Cross-Linked Polymer That Lowers Serum Potassium Concentration in Patients With Hyperkalemia

Vinyl and methyl-ester groups in the insoluble polymer drug patiromer identified and quantified by solid-state NMR

Patiromer (Veltassa®) is a crosslinked, insoluble co-polymer drug used as a nonabsorbent potassium binder, approved for treatment of hyperkalemia. Quantitative solid-state 13C nuclear magnetic resonance (NMR) analysis with comprehensive peak assignment, component quantification, and calculation of mole and weight fractions of monomer units was performed on three doses of patiromer. The workflow is documented in detail. Spectrally edited solid-state 13C NMR spectra of patiromer show =CHn peaks of matching intensity at 116 and 141 ppm, characteristic of -CH=CH2 vinyl groups. Similar spectral features can be observed in earlier studies but were previously ignored. In this study, the vinyl signals are well-resolved in a 2-s direct polarization (DP) spectrum without and with dipolar dephasing, which confirms that these sp2-hybridized carbons are bonded to hydrogen and partially mobile, consistent with vinyl side groups from incompletely reacted divinyl crosslinkers. The vinyl groups account for 1.6% of all carbon, 3% of the monomer units, and nearly 1/3 of the crosslinkers. Furthermore, an unexpected OCH3 moiety accounting for ∼1.2% of all carbons was identified by spectral editing; its chemical shift of 54 ppm is more consistent with a methyl ester than with a methyl ether. It can originate from incomplete hydrolysis of ∼6% of methyl-2-fluoroacrylate, the main monomer of patiromer. Characteristic cross peaks in two-dimensional 1H-13C heteronuclear correlation NMR confirm the presence of the vinyl and OCH3 groups. Trace amounts of xanthan gum are also detected. The quantitative 13C NMR spectrum of patiromer has been matched in a simulation using a model with five monomer units.

The U.S. FDA approved cardiovascular drugs from 2011 to 2023: A medicinal chemistry perspective

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality worldwide. A total of 28 new molecular entities (NMEs) were approved by the U.S. Food and Drug Administration (FDA) for the treatment of cardiovascular diseases from 2011 to 2023. Approximately 25 % of the medications were sanctioned for the management of diverse vascular disorders. The other major therapeutic areas of focus included antilipemic agents (15 %), blood pressure disease (11 %), heart failure, hyperkalemia, and cardiomyopathy (7-8% each). Among all the approved drugs, there are a total of 22 new chemical entities (NCEs), including inhibitors, agonists, polymers, and inorganic compounds. In addition to NCEs, 6 biological agents (BLAs), including monoclonal antibodies, small interfering RNAs (siRNAs), and antisense oligonucleotides, have also obtained approval for the treatment of cardiovascular diseases. From this perspective, approved NCEs are itemized and discussed based on their disease, targets, chemical classes, major drug metabolites, and biochemical and pharmacological properties. Systematic analysis has been conducted to examine the binding modes of these approved drugs with their targets using cocrystal structure information or docking studies to provide valuable insights for designing next-generation agents. Furthermore, the synthetic approaches employed in the creation of these drug molecules have been emphasized, aiming to inspire the development of novel, efficient, and applicable synthetic methodologies. Generally, the primary objective of this review is to provide a comprehensive examination of the clinical applications, pharmacology, binding modes, and synthetic methodologies employed in small-molecule drugs approved for treating CVD. This will facilitate the development of more potent and innovative therapeutics for effectively managing cardiovascular diseases.

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.

Upper Gastrointestinal Bleeding Secondary to Sodium Polystyrene Sulfonate Use: A Rare Adverse Effect of Commonly Prescribed Treatment

We report a case of a 62-year-old man who was brought in by emergency medical services after a fall and change in mental status. He was found to have severe hyperkalemia, acute kidney injury, and rhabdomyolysis. The hyperkalemia was treated with sodium polystyrene sulfonate (SPS). During hospitalization, he witnessed having black tarry stools along with a significant drop in hemoglobin. Endoscopic evaluation demonstrated nonbleeding large diffuse gastric ulcers with stigmata of recent bleeding, and ulcer biopsy revealed findings consistent with SPS-induced gastric ulceration. No other source of bleeding was localized, suggesting acute upper gastrointestinal bleeding due to SPS mucosal injury.

The efficacy and safety of new potassium binders on renin-angiotensin-aldosterone system inhibitor optimization in heart failure patients: a systematic review and meta-analysis

Guideline-directed medical therapy (GDMT) has improved outcomes in patients with heart failure, including the use of renin-angiotensin-aldosterone system inhibitors, which can hinder the excretion of potassium, resulting in hyperkalaemia. New potassium binders (NPBs) can prevent this adverse effect; however, the efficacy and safety of NPB for this indication have not been fully established. We conducted a systematic review and meta-analysis synthesizing randomized controlled trials (RCTs), which were retrieved by systematically searching PubMed, Web of Science, Scopus, and Cochrane through 26 April 2023. The risk of bias assessment was conducted, following Cochrane's updated Risk of Bias 2 assessment tool. We used the fixed-effects model to pool dichotomous data using risk ratio (RR) and continuous data using mean difference (MD), with a 95% confidence interval (CI) (PROSPERO ID: CRD42023426113). We included six RCTs with a total of 1432 patients. NPB was significantly associated with successful mineralocorticoid receptor antagonist (MRA) optimization [RR: 1.13 with 95% CI (1.02-1.25), P = 0.02], decreased patients with MRA at less than the target dose [RR: 0.72 with 95% CI (0.57-0.90), P = 0.004], and decreased hyperkalaemic episodes [RR: 0.42 with 95% CI (0.24-0.72), P = 0.002]. However, there was no difference between NPB and placebo regarding angiotensin-converting enzyme inhibitor (ACEi)/angiotensin receptor blocker (ARB)/angiotensin receptor/neprilysin inhibitor (ANRi) optimization [RR: 1.02 with 95% CI (0.89-1.17), P = 0.76] and serum potassium change [MD: -0.31 with 95% CI (-0.61 to 0.00), P = 0.05], with an acceptable safety profile except for the increased incidence of hypokalaemia with NPB [RR: 1.57 with 95% CI (1.12-2.21), P = 0.009]. NPB has been shown to improve GDMT outcomes by enhancing MRA optimization and reducing hyperkalaemic episodes. However, there are limited data on the effects of NPB on ACEi/ARB/ANRi optimization. Future RCTs should investigate ACEi/ARB/ANRi optimization and conduct head-to-head comparisons of NPB (patiromer and sodium zirconium cyclosilicate).

Magnesium and Vascular Calcification in Chronic Kidney Disease: Current Insights

Magnesium (Mg) plays crucial roles in multiple essential biological processes. As the kidneys are the primary organ responsible for maintaining the blood concentration of Mg, people with chronic kidney disease (CKD) may develop disturbances in Mg. While both hyper- and hypomagnesemia may lead to adverse effects, the consequences associated with hypomagnesemia are often more severe and lasting. Importantly, observational studies have shown that CKD patients with hypomagnesemia have greater vascular calcification. Vascular calcification is accelerated and contributes to a high mortality rate in the CKD population. Both in vitro and animal studies have demonstrated that Mg protects against vascular calcification via several potential mechanisms, such as inhibiting the formation of both hydroxyapatite and pathogenic calciprotein particles as well as limiting osteogenic differentiation, a process in which vascular smooth muscle cells in the media layer of the arteries transform into bone-like cells. These preclinical findings have led to several important clinical trials that have investigated the effects of Mg supplementation on vascular calcification in people with CKD. Interestingly, two major clinical studies produced contradictory findings, resulting in a state of equipoise. This narrative review provides an overview of our current knowledge in the renal handling of Mg in health and CKD and the underlying mechanisms by which Mg may protect against vascular calcification. Lastly, we evaluate the strength of evidence from clinical studies on the efficacy of Mg supplementation and discuss future research directions.

Effects of Patiromer and Sodium Zirconium Cyclosilicate on Blood Pressure in Rats with Chronic Kidney Disease

BACKGROUND

Potassium-binders patiromer and sodium zirconium cyclosilicate (SZC) are approved to treat hyperkalaemia, which is frequently observed in chronic kidney disease (CKD). Elevated blood pressure (BP) is common in CKD, due in part to impaired sodium excretion. The effect of patiromer, which exchanges calcium for potassium and SZC, which exchanges sodium or hydrogen for potassium, on BP was assessed in a CKD rat model.

METHODS

Thirty-six Sprague Dawley rats with 5/6 nephrectomy were randomised to three groups (n = 12/group) to receive 4 g/kg/day patiromer or SZC, or vehicle treatment, for 8 weeks. BP was determined by radiotelemetry and urinary protein and electrolytes were measured.

RESULTS

At Week 8, systolic BP (sBP) increased in all groups; however, patiromer led to a lower mean (standard deviation) sBP than vehicle or SZC (141 [2.9] vs 158 [5.2] or 162 [6.1] mm Hg, respectively, both p < 0.001), with no difference in sBP between vehicle and SZC (p = 0.08). Similar results were observed for diastolic BP. Serum potassium levels fell with SZC (p < 0.02), but not vehicle or patiromer. Urine potassium decreased with both patiromer and SZC versus vehicle (p < 0.01); urine sodium increased with SZC (p < 0.01); and urine calcium increased with patiromer (p < 0.01). Urine phosphorus decreased with patiromer (p < 0.01) but increased with SZC (p < 0.01). Patiromer resulted in less proteinuria than vehicle or SZC (both p < 0.017).

CONCLUSIONS

After 8 weeks, treatment with patiromer resulted in lower BP in rats than vehicle or SZC. Further studies are needed to determine the mechanism of the differential effect of potassium binders on rat BP.

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.

Maintaining Renin-Angiotensin-Aldosterone System Inhibitor Treatment with Patiromer in Hyperkalaemic Chronic Kidney Disease Patients: Comparison of a Propensity-Matched Real-World Population with AMETHYST-DN

INTRODUCTION

Guideline-directed renin-angiotensin-aldosterone system inhibitor (RAASi) therapy is rarely achieved in clinical settings, often due to hyperkalaemia. We assessed the potassium binder, patiromer, on continuation of RAASi therapy in hyperkalaemic patients with chronic kidney disease (CKD) and type 2 diabetes mellitus (T2DM) in the AMETHYST-DN trial, propensity score-matched to a real-world cohort not receiving patiromer (Salford Kidney Study).

METHODS

The phase 2, open-label AMETHYST-DN trial (NCT01371747) randomized 304 adults with CKD on RAASi, T2DM, hyperkalaemia (serum potassium [sK+] >5.0 mEq/L), and hypertension to receive patiromer, 8.4-33.6 g/day for 12 months. Patients underwent propensity score matching for systolic blood pressure (BP), heart failure status, and estimated glomerular filtration rate (eGFR), with 321 patients with CKD, T2DM, hyperkalaemia, and on RAASi from a prospective CKD cohort (Salford Kidney Study). Changes in RAASi utilization, sK+, BP, proteinuria, and eGFR during 12-month follow-up were assessed by Mann-Whitney U or χ2 tests.

RESULTS

Matching produced 135:135 patients with no significant differences in age, sex, systolic BP, sK+, eGFR, or heart failure status, although differences in diastolic BP remained (p < 0.001). After 12 months, 100% of AMETHYST-DN patients receiving patiromer remained on RAASi therapy, whereas 38.5% of the Salford Kidney Cohort discontinued RAASi (p < 0.001); hyperkalaemia contributed in 16% of patients (42% of RAASi discontinuations). Significantly greater reductions in sK+ and BP, but not proteinuria or eGFR, were observed in AMETHYST-DN, compared with Salford Kidney Study patients (p < 0.05).

CONCLUSIONS

These results demonstrate the benefit of patiromer for sK+ management to enable RAASi use while revealing beneficial effects on BP.

Patiromer Treatment in Patients With CKD, Hyperkalemia, and Hyperphosphatemia: A Post Hoc Analysis of 3 Clinical Trials

RATIONALE & OBJECTIVE

Patients with chronic kidney disease (CKD), hyperkalemia (serum potassium [sK+]>5.0 mEq/L), and hyperphosphatemia experience poor clinical outcomes. Patiromer, a potassium binder that uses calcium as the exchange ion, may also reduce serum phosphorus (sP). We characterized the effect of patiromer on sP in patients with CKD, hyperkalemia, and hyperphosphatemia.

STUDY DESIGN

A post hoc pooled analysis of individual-level data from the AMETHYST-DN, OPAL-HK, and TOURMALINE trials of patiromer.

SETTING & PARTICIPANTS

Patients with CKD and hyperkalemia.

EXPOSURE

Patients treated with patiromer (8.4-33.6 g/day).

OUTCOME

Mean changes from baseline in sP, sK+, serum calcium (sCa2+), and serum magnesium (sMg2+) after 2 and 4 weeks of treatment.

ANALYTICAL APPROACH

Descriptive statistics to summarize pooled data on the study outcomes from the 3 studies.

RESULTS

We included 578 patients in the analysis. Of these participants, 86 patients (14.9%) had baseline hyperphosphatemia of whom 75.6% (65 of 86) had CKD stage 4/5 and 31.1% (153 of 492) with sP≤4.5mg/dL had CKD stage 4/5. Among the patients with elevated sP and sK+at baseline, the mean±SD reduction in sP and sK+after 4 weeks of patiromer treatment was-0.62±1.09mg/dL and-0.71± 0.51 mEq/L, respectively. Additionally, the mean±SD reduction in sMg2+in these patients was -0.25±0.23mg/dL while sCa2+remained unchanged. Both sMg2+and sCa2+remained within the normal range. Patiromer was generally well tolerated, and no serious adverse events were considered related to patiromer.

LIMITATIONS

These were post hoc analyses, no placebo comparison was performed due to the design of the original studies, and the follow-up period was limited to 4 weeks.

CONCLUSIONS

Reductions in sP and sK+to the normal range were observed after 2 weeks of patiromer treatment, and the reduction was sustained during 4 weeks of treatment among patients with non-dialysis-dependent CKD, hyperkalemia, and hyperphosphatemia. Future controlled trials are needed to establish if patiromer is useful to reduce both sK+and sP in hyperkalemic patients with CKD and hyperphosphatemia.

Patiromer utility as an adjunct treatment in patients needing urgent hyperkalaemia management (PLATINUM): design of a multicentre, randomised, double-blind, placebo-controlled, parallel-group study

INTRODUCTION

Hyperkalaemia is common, life-threatening and often requires emergency department (ED) management; however, no standardised ED treatment protocol exists. Common treatments transiently reducing serum potassium (K+) (including albuterol, glucose and insulin) may cause hypoglycaemia. We outline the design and rationale of the Patiromer Utility as an Adjunct Treatment in Patients Needing Urgent Hyperkalaemia Management (PLATINUM) study, which will be the largest ED randomised controlled hyperkalaemia trial ever performed, enabling assessment of a standardised approach to hyperkalaemia management, as well as establishing a new evaluation parameter (net clinical benefit) for acute hyperkalaemia treatment investigations.

METHODS AND ANALYSIS

PLATINUM is a Phase 4, multicentre, randomised, double-blind, placebo-controlled study in participants who present to the ED at approximately 30 US sites. Approximately 300 adult participants with hyperkalaemia (K+ ≥5.8 mEq/L) will be enrolled. Participants will be randomised 1:1 to receive glucose (25 g intravenously <15 min before insulin), insulin (5 units intravenous bolus) and aerosolised albuterol (10 mg over 30 min), followed by a single oral dose of either 25.2 g patiromer or placebo, with a second dose of patiromer (8.4 g) or placebo after 24 hours. The primary endpoint is net clinical benefit, defined as the mean change in the number of additional interventions less the mean change in serum K+, at hour 6. Secondary endpoints are net clinical benefit at hour 4, proportion of participants without additional K+-related medical interventions, number of additional K+-related interventions and proportion of participants with sustained K+ reduction (K+ ≤5.5 mEq/L). Safety endpoints are the incidence of adverse events, and severity of changes in serum K+ and magnesium.

ETHICS AND DISSEMINATION

A central Institutional Review Board (IRB) and Ethics Committee provided protocol approval (#20201569), with subsequent approval by local IRBs at each site, and participants will provide written consent. Primary results will be published in peer-reviewed manuscripts promptly following study completion.

TRIAL REGISTRATION NUMBER

NCT04443608.

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.

Understanding and Treatment Strategies of Hypertension and Hyperkalemia in Chronic Kidney Disease

Hypertension and potassium imbalance are commonly observed in chronic kidney disease (CKD) patients. The development of hypertension would be related to several mechanisms. Hypertension is related to body mass index, dietary salt intake, and volume overload and is treated with antihypertensives. In CKD patients, managing hypertension can provide important effects that can slow the progression of CKD or reduce complications associated with reduced glomerular filtration rate. The prevalence of hyperkalemia and hypokalemia in CKD patients was similar at 15-20% and 15-18%, respectively, but more attention needs to be paid to treating and preventing hyperkalemia, which is related to a higher mortality rate, than hypokalemia. Hyperkalemia is prevalent in CKD due to impaired potassium excretion. Serum potassium level is affected by renin-angiotensin-aldosterone system inhibitors and diuretics and dietary potassium intake and can be managed by potassium restriction dietary, optimized renin-angiotensin-aldosterone system inhibitor, sodium polystyrene sulfonate, patiromer, and hemodialysis. This review discussed strategies to mitigate and care for the risk of hypertension and hyperkalemia in CKD patients.

Safety and efficacy of new potassium binders on hyperkalemia management in patients with heart failure: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Hyperkalemia leads to suboptimal use of evidence-based therapies in patients with heart failure (HF). Therefore, we aimed to assess whether new potassium binders are effective and safe to promote medical optimization in patients with HF.

METHODS

MEDLINE, Cochrane, and Embase were searched for randomized controlled trials (RCTs) that reported outcomes after initiation of Patiromer or Sodium Zirconium Cyclosilicate (SZC) versus placebo in patients with HF at high risk of hyperkalemia development. Risk ratios (RR) with 95% confidence intervals (CI) were pooled with a random effects model. Quality assessment and risk of bias were performed according to Cochrane recommendations.

RESULTS

A total of 1432 patients from 6 RCTs were included, of whom 737 (51.5%) patients received potassium binders. In patients with HF, potassium binders increased the use of renin-angiotensin-aldosterone inhibitors (RR 1.14; 95% CI 1.02-1.28; p = 0.021; I² = 44%) and reduced the risk of hyperkalemia (RR 0.66; 95% CI 0.52-0.84; p < 0.001; I² = 46%). The risk of hypokalemia was significantly increased in patients treated with potassium binders (RR 5.61; 95% CI 1.49-21.08; p = 0.011; I² = 0%). There was no difference between groups in all-cause mortality rates (RR 1.13; 95% CI 0.59-2.16; p = 0.721; I² = 0%) or in adverse events leading to drug discontinuation (RR 1.08; 95% CI 0.60-1.93; p = 0.801; I² = 0%).

CONCLUSION

The use of new potassium binders Patiromer or SZC in patients with HF at risk for hyperkalemia increased the rates of medical therapy optimization with renin-angiotensin-aldosterone inhibitors and reduced the incidence of hyperkalemia, at the cost of an increased prevalence of hypokalemia.

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.

A New Understanding of Potassium's Influence Upon Human Health and Renal Physiology

Potassium channels are expressed in virtually all cell types, and their activity is the dominant determinant of cellular membrane potential. As such, potassium flux is a key regulator of many cellular processes including the regulation of action potentials in excitable cells. Subtle changes in extracellular potassium can initiate signaling processes vital for survival (insulin signaling) while more extreme and chronic changes may lead to pathological states (acid-base disturbances and cardiac arrhythmia). While many factors acutely influence extracellular potassium levels, it is principally the role of the kidneys to maintain potassium balance by matching urinary excretion with dietary intake. When this balance is disrupted, human health is negatively impacted. In this review, we discuss evolving views of dietary potassium intake as means of preventing and mitigating diseases. We also provide an update on a molecular pathway called the potassium switch, a mechanism by which extracellular potassium regulates distal nephron sodium reabsorption. Finally, we review recent literature describing how several popular therapeutics influence potassium homeostasis.

Patiromer utilization in patients with advanced chronic kidney disease under nephrology care in Germany

Background

Hyperkalemia (HK) is a frequent condition in patients with chronic kidney disease (CKD) that is associated with high morbidity and mortality. Patiromer has recently been introduced as a potassium binder. Data on patiromer use in patients with CKD in the real-world setting in Europe are lacking. We describe time to discontinuation and changes in serum potassium levels among German CKD stage 3-5 patients starting patiromer.

Methods

Duration of patiromer use was estimated by Kaplan-Meier curve, starting at patiromer initiation and censoring for death, dialysis, transplant or loss to follow-up. Serum potassium levels and renin-angiotensin-aldosterone system inhibitor (RAASi) use are described at baseline and during follow-up, restricted to patients remaining on patiromer.

Results

We identified 140 patiromer users within our analysis sample [81% CKD stage 4/5, 83% receiving RAASi, and median K+ 5.7 (5.4, 6.3) mmol/L]. Thirty percent of patiromer users had prior history of polystyrene sulfonate use. Overall, 95% of patiromer users stayed on treatment past 1 month, with 53% continuing for over a year. Mean serum potassium levels decreased after patiromer initiation and remained stable under treatment during follow-up (up to 180 days). Among these patients, 73%-82% used RAASis during the time periods before and after patiromer initiation, with no obvious trend indicating discontinuation.

Conclusion

Real-world evidence of patiromer use in Germany shows that, in line with what has been observed in clinical trials, patients on patiromer have a reduction in serum potassium when used long-term. Moreover, most patients on patiromer do not discontinue treatment prior to 1 year after initiation.

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.

Clinical Efficacy, Safety, Tolerability, and Real-World Data of Patiromer for the Treatment of Hyperkalemia

Hyperkalemia remains one of the most difficult consequences of disease state and treatment for patients with chronic kidney disease, heart failure, and diabetes. Controlling hyperkalemia can be difficult, but has become easier with the introduction of novel oral potassium binders. Patiromer was approved in 2015 for the treatment of hyperkalemia by the FDA in the United States. Several pivotal trials proved its efficacy, safety, and improved tolerability compared with previous hyperkalemia treatments. Additionally, many real-world publications and trials have given deeper insights into the capabilities of patiromer. We discuss improved disease state outcomes with combining patiromer with RAASi. This paper will also highlight new trials forthcoming that are highly anticipated to expand the possibilities in using patiromer to improve outcomes and populations.

Experience with the potassium binder patiromer in hyperkalaemia management in heart failure patients in real life

AIMS

Hyperkalaemia (HK) is common in heart failure (HF) patients, related to renal dysfunction and medical treatment. It limits medical therapy optimization, which impacts prognosis. New potassium (K) binders help control HK, allowing better medical management of HF.

METHODS AND RESULTS

A retrospective multicentre register included all outpatients with HF and HK (K ≥ 5.1 mEq/L) treated with patiromer according to current recommendations. We evaluated analytic and clinical parameters before starting the treatment and at 7, 30 and 90 days, as well as adverse events related to patiromer and treatment optimization. We included 74 patients (71.6% male) with a mean age of 70.8 years (SD 9.2). Sixty-seven patients (90.5%) presented HK in the previous year. Forty patients (54.1%) underwent down-titration of a renin-angiotensin-aldosterone inhibitor (RAASi) or a mineralocorticoid receptor antagonist (MRA), and 27 (36.5%) stopped any of them due to HK. Initial K was 5.5 mEq/L (SD 0.6), with a significantly reduction at 7 days (4.9 mEq/L (SD 0.8); P < 0.001), maintained at 90 days (4.9 mEq/L (SD 0.8); P < 0.001). There were no other electrolyte disturbances, with a slight improvement in renal function [glomerular filtration rate 39.6 mL/min (SD 20.4) to 42.7 mL/min (SD 23.2); P = 0.005]. Adverse events were reported in 33.9% of patients, the most common being hypomagnesaemia (16.3%), gastrointestinal disturbances (14.9%) and HK (2.8%). Withdrawal of patiromer was uncommon (12.2%) due to gastrointestinal disturbances in 66.7% of cases. Nine patients (12.2%) started on a RAASi, and 15 patients (20.3%) on an MRA during the follow-up. Forty-five patients (60.8%) increased the dose of RAASi or MRA, increasing to target doses in 5.4 and 10.8% of patients, respectively. At 90 days, NTproBNP values were reduced from 2509.5 pg/mL [IQR 1311-4,249] to 1396.0 pg/mL [IQR 804-4263]; P = 0.003, but the reduction was only observed in those who optimized HF medical treatment [NTproBNP from 1950.5 pg/mL (IQR 1208-3403) to 1349.0 pg/mL (IQR 804-2609); P < 0.01]. NYHA functional class only improved in 7.5% of patients, corresponding with those who optimized HF medical treatment. Compared with the previous 3 months before patiromer treatment, the rate of hospitalization was reduced from 28.4 to 10.9% (P < 0.01), and the emergency room visits from 18.9 to 5.4% (P < 0.01).

CONCLUSIONS

In a real-life cohort of patients with HF, patiromer reduced and maintained K levels during 3 months of follow-up. The most common adverse events were hypomagnesaemia and gastrointestinal disturbances. Patiromer helps optimize medical treatment, increasing the percentage of patients treated with RAASi and MRA at target doses. At the end of follow-up, natriuretic peptides values and hospital visits were reduced, suggesting the benefit of optimizing HF medical treatment.

Can Novel Potassium Binders Liberate People with Chronic Kidney Disease from the Low-Potassium Diet? A Cautionary Tale

The advent of new potassium binders provides an important breakthrough in the chronic management of hyperkalemia for people with CKD. In addition to the direct benefits of managing hyperkalemia, many researchers and clinicians view these new medications as a possible means to safely transition patients away from the low-potassium diet to a more healthful eating pattern. In this review, we examine the mechanisms of potassium binders in the context of hyperkalemia risk related to dietary potassium intake in people with CKD. We note that whereas these medications target hyperkalemia caused by potassium bioaccumulation, the primary evidence for restricting dietary potassium is risk of postprandial hyperkalemia. The majority of ingested potassium is absorbed alongside endogenously secreted potassium in the small intestines, but the action of these novel medications is predominantly constrained to the large intestine. As a result and despite their effectiveness in lowering basal potassium levels, it remains unclear whether potassium binders would provide protection against hyperkalemia caused by excessive dietary potassium intake in people with CKD. Until this knowledge gap is bridged, clinicians should consider postprandial hyperkalemia risk when removing restrictions on dietary potassium intake in people with CKD on potassium binders.

OUP accepted manuscript

Background

Hyperkalaemia is frequent in haemodialysis (HD) patients and associated with increased cardiovascular mortality. Despite routine clinical use, evidence regarding the efficacy of potassium (K⁺) binders in HD is scant. We wished to compare the efficacy of patiromer (PAT) and sodium polystyrene sulfonate (SPS) on K⁺ levels in this setting.

Methods

We screened patients in three HD centres with pre-HD K⁺ value between 5.0 and 6.4 mmol/L, after an initial 2-week washout period for those previously on K⁺ binders. We included patients in an unblinded two-arm crossover trial comparing SPS 15 g before each meal on non-dialysis days with PAT 16.8 g once daily on non-dialysis days with randomized attribution order and a 2-week intermediate washout period. The primary outcome was the mean weekly K⁺ value.

Results

We included 51 patients and analysed 48 with mean age of 66.4 ± 19.4 years, 72.9% men and 43.4% diabetics. Mean weekly K⁺ values were 5.00 ± 0.54 mmol/L, 4.55 ± 0.75 mmol/L and 5.17 ± 0.64 mmol/L under PAT (P = .003), SPS (P < .001) and washout, respectively. In direct comparison, K⁺ values and prevalence of hyperkalaemia were lower under SPS as compared with PAT (P < .001). While the incidence of gastrointestinal side effects was similar between treatments, SPS showed lower subjective tolerability score (6.0 ± 2.4 and 6.9 ± 1.9) and compliance (10.8 ± 20.4% and 2.4 ± 7.3% missed doses) as compared with PAT (P < .001 for both).

Conclusion

Both PAT and SPS are effective in decreasing K⁺ levels in chronic HD patients. However, at the tested doses, SPS was significantly more effective in doing so as compared with PAT, despite lower tolerability and compliance. Larger randomized controlled trials should be conducted in order to confirm our findings and determine whether they would impact clinical outcomes.

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.

Possible Advantages Deriving from Patiromer Use in Hypertensive Patients Made Hyperkalemic by Renin-Angiotensin-Aldosterone Blocking Agents

Hyperkalemia is an elevated level of serum potassium (K⁺) and does represent a life-threatening condition. In clinical practice, hyperkalemia mainly derives from an impaired renal K⁺ excretion which, in turn, is usually caused by either acute or chronic renal failure. In concordance with this, hyperkalemia is very common in several chronic conditions, such as kidney disease, diabetes mellitus, heart failure, hypertension, and coronary heart disease. In all of these conditions the use of Renin-Angiotensin-Aldosterone System inhibitors (RAASIs), such as angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs), and mineralocorticoid receptor antagonist is widely recommended and further increases the risk of hyperkalemia. As hypertension is concerned, clinical trials suggest that the risk of hyperkalemia associated with RAASIs ranges from 2 to 10%. This often leads to a reduction or complete cessation of RAASIs, leaving patients without protective medications. Patiromer, a new oral potassium-binding agent, has been approved for clinical use in several countries, including Europe and US. Clinical studies have demonstrated that patiromer is effective in inducing a rapid and sustained K⁺ reduction in various patient settings, including those where RAASIs are a fundamental component of cardiorenal protection. Patiromer is generally well tolerated and characterised by a good safety profile. Most importantly, patiromer use might allow the continuation of ACEIs and ARBs in hypertensive patients developing hyperkalemia during treatment and thereby favour a more effective and long-lasting cardiorenal protection.

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.

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.

Management of Chronic Hyperkalemia in Patients With Chronic Kidney Disease: An Old Problem With News Options

Hyperkalemia is one of the main electrolyte disorders in patients with chronic kidney disease (CKD). The prevalence of hyperkalemia increases as the Glomerular Filtration Rate (GFR) declines. Although chronic hyperkalemia is not a medical emergency, it can have negative consequences for the adequate cardio-renal management in the medium and long term. Hyperkalemia is common in patients on renin-angiotensin-aldosterone system inhibitors (RAASi) or Mineralocorticoid Receptor Antagonists (MRAs) and can affect treatment optimization for hypertension, diabetes mellitus, heart failure (HF), and CKD. Mortality rates are higher with suboptimal dosing among patients with CKD, diabetes or HF compared with full RAASi dosing, and are the highest among patients who discontinue RAASis. The treatment of chronic hyperkalemia is still challenging. Therefore, in the real world, discontinuation or reduction of RAASi therapy may lead to adverse cardiorenal outcomes, and current guidelines differ with regard to recommendations on RAASi therapy to enhance cardio and reno-protective effects. Treatment options for hyperkalemia have not changed much since the introduction of the cation exchange resin over 50 years ago. Nowadays, two new potassium binders, Patiromer Sorbitex Calcium, and Sodium Zirconium Cyclosilicate (SZC) already approved by FDA and by the European Medicines Agency, have demonstrated their clinical efficacy in reducing serum potassium with a good safety profile. The use of the newer potassium binders may allow continuing and optimizing RAASi therapy in patients with hyperkalemia keeping the cardio-renal protective effect in patients with CKD and cardiovascular disease. However, further research is needed to address some questions related to potassium disorders (definition of chronic hyperkalemia, monitoring strategies, prediction score for hyperkalemia or length for treatment).

Increased colonic K+ excretion through inhibition of the H,K-ATPase type 2 helps reduce plasma K+ level in a murine model of nephronic reduction

Hyperkalemia is frequently observed in patients at the end-stage of chronic kidney disease (CKD), and has possible harmful consequences on cardiac function. Many strategies are currently used to manage hyperkalemia, one consisting of increasing fecal K⁺ excretion through the administration of cation-exchange resins. In this study, we explored another more specific method of increasing intestinal K⁺ secretion by inhibiting the H,K-ATPase type 2 (HKA2), which is the main colonic K⁺ reabsorptive pathway. We hypothetised that the absence of this pump could impede the increase of plasma K⁺ levels following nephronic reduction (N5/6) by favoring fecal K⁺ secretion. In N5/6 WT and HKA2KO mice under normal K⁺ intake, the plasma K⁺ level remained within the normal range, however, a load of K⁺ induced strong hyperkalemia in N5/6 WT mice (9.1 ± 0.5 mM), which was significantly less pronounced in N5/6 HKA2KO mice (7.9 ± 0.4 mM, p < 0.01). This was correlated to a higher capacity of HKA2KO mice to excrete K⁺ in their feces. The absence of HKA2 also increased fecal Na⁺ excretion by inhibiting its colonic ENaC-dependent absorption. We also showed that angiotensin-converting-enzyme inhibitor like enalapril, used to treat hypertension during CKD, induced a less severe hyperkalemia in N5/6 HKA2KO than in N5/6 WT mice. This study therefore provides the proof of concept that the targeted inhibition of HKA2 could be a specific therapeutic maneuver to reduce plasma K⁺ levels in CKD patients.

Effect of patiromer on serum potassium in hyperkalemic patients with heart failure: Pooled analysis of 3 randomized trials

BACKGROUND

Hyperkalemia (HK) is a serious medical condition that can cause potentially fatal cardiac arrhythmias. Patients with heart failure (HF) are at risk of HK due to underlying chronic kidney disease and use of guideline-recommended renin-angiotensin-aldosterone system inhibitors. Patiromer, a sodium-free, non-absorbed potassium (K⁺) binder, is indicated for the treatment of HK.

OBJECTIVE

To evaluate the consistency of patiromer's effect on lowering serum K⁺ in patients with HF and HK using pooled data from three clinical trials.

METHODS

This post-hoc analysis evaluated the efficacy and safety of patiromer for management of HK over a 4-week treatment period using combined data from three clinical trials (AMETHYST-DN, OPAL-HK and TOURMALINE). Eligible patients had HK (serum K⁺ > 5.0 mEq/L) at study entry. Starting doses of patiromer ranged from 8.4 to 33.6 g/day. In this analysis, efficacy was assessed as the mean (± standard error [SE]) change in serum K⁺ from baseline to Week 4. Safety outcomes evaluated included the incidence and severity of adverse events (AEs) during the 4-week treatment period.

RESULTS

In total, 653 patients who received ≥1 dose of patiromer were evaluable for efficacy (214 diagnosed with HF and 439 without HF). Mean baseline serum K⁺ was 5.4 mEq/L. Patient characteristics were generally similar between the HF and non-HF subgroups. Serum K⁺ decreased to <5.0mEq/L within one week of patients starting patiromer, reaching a nadir after 3 weeks in both the HF and non-HF subgroups (4.59 mEq/L and 4.64 mEq/L, respectively). The mean ± SE change from baseline to Week 4 in serum K⁺ was -0.79 ± 0.06 mEq/L (95% CI: -0.91, -0.68) in patients with HF and - 0.75 ± 0.02 mEq/L (95% CI: -0.79, -0.70) in patients without HF. AEs occurred in 31% of patients with HF and 37% of patients without HF and were mostly mild or moderate in severity. The most common AEs were constipation (HF patients: 7%, non-HF patients: 5%) and diarrhea (HF patients: 2%, non-HF patients: 4%). AEs leading to discontinuation of patiromer occurred in 7% of patients with HF and in 3% of patients without HF.

CONCLUSIONS

In this pooled analysis of patients with HK, patiromer was generally well tolerated and reduced serum K⁺ similarly in patients with and without HF over 4 weeks.

Hyperkalemia in heart failure

Hyperkalemia is increasingly prevalent in the heart failure population as more people live with heart failure and comorbid conditions such as diabetes and chronic kidney disease. Furthermore, renin–angiotensin–aldosterone (RAAS) inhibitors are a key component of clinical therapy in these populations. Until now, we have not had any reliable or tolerable therapies for treatment of hyperkalemia resulting in inability to implement or achieve target doses of RAAS inhibition. This review will focus on two new therapies for hyperkalemia: patiromer and sodium zirconium cyclosilicate (SZC).

Pharmacodynamic effects of the K+ binder patiromer in a novel chronic hyperkalemia model in spontaneously hypertensive rats

Currently described hyperkalemia (HK) animal models are typically acute and cause significant distress and mortality to the animals, warranting new approaches for studying chronic HK in a more appropriate clinical setting. Using the spontaneously hypertensive rat (SHR) model as a more relevant disease template, as well as surgical (unilateral nephrectomy), dietary (3% potassium [K+ ] supplementation), and pharmacological (amiloride) interventions, we were able to stably induce HK on a chronic basis for up to 12 weeks to serum K+ elevations between 8 and 9 mmol/L, with minimal clinical stress to the animals. Short-term proof-of-concept and long-term chronic studies in hyperkalemic SHRs showed concomitant increases in serum aldosterone, consistent with the previously reported relationship between serum K+ and aldosterone. Treatment with the K+ binder patiromer demonstrated that the disease model was responsive to pharmacological intervention, with significant abrogation in serum K+ , as well as serum aldosterone to levels near baseline, and this was consistent in both short-term and long-term 12-week chronic studies. Our results demonstrate the feasibility of establishing a chronic HK disease state, and this novel HK animal model may be suitable for further evaluating the effects of long-term, K+ -lowering therapies on effects such as renal fibrosis and end-organ damage.

The potassium regulator patiromer affects serum and stool electrolytes in patients receiving hemodialysis

Hyperkalemia is a common and an important cause of death in maintenance hemodialysis patients. Here we investigated the effect of patiromer, a synthetic cation exchanger, to regulate potassium homeostasis. Serum and stool electrolytes were measured in 27 anuric patients with hyperkalemia receiving hemodialysis (mainly 2 mEq/L dialysate) during consecutive two weeks of no-treatment, 12 weeks of treatment with patiromer (16.8g once daily), and six weeks of no treatment. The serum potassium decreased from a mean of 5.7 mEq/L pre-treatment to 5.1 mEq/L during treatment and rebounded to 5.4 mEq/L post-treatment. During the treatment phase, serum calcium significantly increased (from 8.9 to 9.1 mg/dL) and serum magnesium significantly decreased (from 2.6 to 2.4 mg/dL) compared to pre-treatment levels. For each one mEg/L increase in serum magnesium, serum potassium increased by 1.07 mEq/L. Stool potassium significantly increased during treatment phase from pre-treatment levels (4132 to 5923 μg/g) and significantly decreased post-treatment to 4246 μg/g. For each one μg/g increase in stool potassium, serum potassium significantly declined by 0.05 mEq/L. Stool calcium was significantly higher during the treatment phase (13017 μg/g) compared to pre-treatment (7874 μg/g) and post-treatment (7635 μg/g) phases. We estimated that 16.8 g of patiromer will increase fecal potassium by 1880 μg/g and reduce serum potassium by 0.5 mEq/L. Thus, there is a complex interaction between stool and blood potassium, calcium and magnesium during patiromer treatment. Long term consequence of patiromer-induced changes in serum calcium and magnesium remains to be studied.

New Treatment Options for Hyperkalemia in Patients with Chronic Kidney Disease

Hyperkalemia may cause life-threatening cardiac and neuromuscular alterations, and it is associated with high mortality rates. Its treatment includes a multifaceted approach, guided by potassium levels and clinical presentation. In general, treatment of hyperkalemia may be directed towards stabilizing cell membrane potential, promoting transcellular potassium shift and lowering total K+ body content. The latter can be obtained by dialysis, or by increasing potassium elimination by urine or the gastrointestinal tract. Until recently, the only therapeutic option for increasing fecal K+ excretion was represented by the cation-exchanging resin sodium polystyrene sulfonate. However, despite its common use, the efficacy of this drug has been poorly studied in controlled studies, and concerns about its safety have been reported. Interestingly, new drugs, namely patiromer and sodium zirconium cyclosilicate, have been developed to treat hyperkalemia by increasing gastrointestinal potassium elimination. These medications have proved their efficacy and safety in large clinical trials, involving subjects at high risk of hyperkalemia, such as patients with heart failure and chronic kidney disease. In this review, we discuss the mechanisms of action and the updated data of patiromer and sodium zirconium cyclosilicate, considering that the availability of these new treatment options offers the possibility of improving the management of both acute and chronic hyperkalemia.

Evolution of Patiromer Use: a Review

PURPOSE OF REVIEW

The purpose of this review is to present data from clinical trials that resulted in the key data supporting the use of patiromer as a potassium binder in clinical practice today.

RECENT FINDINGS

In addition to trials that support the current Food and Drug Administration label and published over the past 3 years, the recently published Spironolactone With Patiromer in the Treatment of Resistant Hypertension in Chronic Kidney Disease (AMBER) trial provides clear benefits of patiromer use in a group of resistant hypertension patients. The AMBER was a phase 2, multicenter, randomized, double-blind, parallel-group, placebo-controlled study that evaluated 295 participants stratified by local serum potassium measurement (4.3 to < 4.7 mmol/L vs 4.7 to 5.1 mmol/L) and history of diabetes and chronic kidney disease. The focus was on enabling participants with resistant hypertension to achieve blood pressure goals by using spironolactone. Additionally, the ongoing Patiromer for the Management of Hyperkalemia in Subjects Receiving RAASi Medications for the Treatment of Heart Failure (DIAMOND) trial is designed to demonstrate how patiromer is an "enabler" of therapies that are needed to either control resistant hypertension or reduce mortality in heart failure but generate hyperkalemia. These and other studies are discussed in detail. Patiromer is one of two new potassium binders that are far better tolerated than the previous agent and can be given chronically to participants who need life-saving therapies but have elevations of potassium into a dangerous range as a consequence.

Hyperkalemia and Hypertension Post Organ Transplantation - A Management Challenge

Potassium is the most important intracellular cation and the kidneys play a pivotal role in potassium homeostasis. Potassium disorder is a common electrolyte abnormality and it increases the risk of death from any cause, particularly cardiovascular events. Hyperkalemia is a common electrolyte abnormality encountered post organ transplantation. The etiology is multifactorial, and includes drugs such as calcineurin inhibitors. In certain regards, the clinical picture of post-transplantation hyperkalemia and hypertension resembles that of Gordon syndrome or familial hyperkalemic hypertension, a disorder characterized by over activity of thiazide-sensitive sodium chloride cotransporter. Effective and safe management of chronic hyperkalemia can be challenging in this special patient population. Despite the significant short-term and long-term side effects, fludrocortisone (a potent synthetic oral mineralocorticoid receptor agonist) has emerged as the default drug of choice for treatment of refractory hyperkalemia in many organ transplant recipients. However, the long-term efficacy and safety of fludrocortisone for management of hyperkalemia in organ transplant recipients remains unknown. This review discusses potassium homeostasis, including the role of the kidneys, and focuses on calcineurin inhibitor-induced hyperkalemia and on the under-appreciated role of thiazide-type diuretic use in management of hyperkalemia and hypertension. We present an illustrative case of post-transplantation hyperkalemia and hypertension with relevant literature.

Optimally managing hyperkalemia in patients with cardiorenal syndrome

Renin-angiotensin-aldosterone system inhibitors (RAASi) are now a standard treatment in most patients with cardiovascular disease, especially in those with heart failure (HF). The European Society of Cardiology and the American College of Cardiology/American Heart Association gave a Class IA recommendation for the use of RAASi in the treatment of Classes II-IV symptomatic HF with reduced ejection fraction (HFREF), based on their strong clinical benefits of lowering all-cause mortality and HF hospitalizations in these subjects. However, RAASi therapy or adding mineralocorticoid receptor antagonists in subjects receiving background angiotensin-converting enzyme inhibitors or angiotensin receptor blockers may be associated with an increased risk of hyperkalemia (HK), especially in those with reduced kidney function. As a result, a significant proportion of these subjects either have RAASi dose reduced or more often discontinued when they develop HK. Discontinuation of RAASi in patients hospitalized with HFREF was associated with higher postdischarge mortality and rehospitalization rates, while optimal dosing of RAASi significantly reduced median hospital stays, outpatient visits and related costs. Thus, effective treatment is required to lower potassium level and maintain normokalemia in subjects with HF and reduced kidney disease who develop or are at risk of HK, thus enabling them to continue their RAASi therapy and maximize benefits from RAASi. In this review, we provide an up-to-date review of the prevalence and significance of HK in patients with cardiorenal syndrome, as well as their optimal management of HK with recent novel therapies.

Quantification of Monomer Units in Insoluble Polymeric Active Pharmaceutical Ingredients Using Solid-State NMR Spectroscopy I: Patiromer

Although extensive precautions are taken to limit batch-to-batch variation in pharmaceutical manufacturing, differences between lots may still exist, particularly in complex formulations. When polymerization is used in the production process, the potential for varying chain lengths and incorporation of different monomers increases the likelihood of batch-to-batch variation. This poses a significant challenge for demonstrating active pharmaceutical ingredient (API) sameness between the innovator and generic drug under development. Therefore, the ability to accurately analyze and quantify the relative amounts of active ingredients present in a formulated product is critically important. Solid-state nuclear magnetic resonance (SSNMR) spectroscopy was used to identify, quantify, and compare the relative amounts of the three polymer groups in the amorphous block copolymer drug, patiromer (Veltassa^®). Techniques such as cross polarization (CP) and magic angle spinning were used to quantify each polymer group while the importance of understanding CP dynamics to obtain quantitative data was also addressed. It was found that the magnetization transfer rate and chemical shift anisotropy for different functional groups present in patiromer play a large role when optimizing parameters for spectral acquisition. Once accounted for, the average patiromer lot contained 90.9%, 7.6%, and 1.5% carboxylate, aromatic, and aliphatic blocks, respectively, with little lot-to-lot variation between different dosage strengths and expiration dates. SSNMR proved to be a sensitive analytical technique for evaluating and quantifying different monomer groups present in patiromer. This procedure may serve as a guide for similar quantitation studies on complex drug products and for demonstrating API sameness during generic drug development.

Current Management of Hyperkalemia in Patients on Dialysis

Patients with end-stage renal disease (ESRD) on maintenance dialysis have a high risk of developing hyperkalemia, generally defined as serum potassium (K⁺) concentrations of >5.0 mmol/l, particularly those undergoing maintenance hemodialysis. Currently, the key approaches to the management of hyperkalemia in patients with ESRD are dialysis, dietary K⁺ restriction, and avoidance of medications that increase hyperkalemia risk. In this review, we highlight the issues and challenges associated with effective management of hyperkalemia in patients undergoing maintenance dialysis using an illustrative case presentation. In addition, we examine the potential nondialysis options for the management of these patients, including use of the newer K⁺ binder agents patiromer and sodium zirconium cyclosilicate, which may reduce the need for the highly restrictive dialysis diet, with its own implication on nutritional status in patients with ESRD, as well as reducing the risk of potentially life-threatening hyperkalemia.

Hyperkalemia treatment modalities: A descriptive observational study focused on medication and healthcare resource utilization

Renin-angiotensin-aldosterone system inhibitor (RAASi) therapy has been shown to improve outcomes among patients with congestive heart failure, diabetes, or renal dysfunction. These patients are also at risk for the development of hyperkalemia (HK), often leading to down-titration and/or discontinuation of RAASi therapy. Patiromer is the first sodium-free, non-absorbed potassium (K⁺) binder approved for the treatment of hyperkalemia (HK) in over 50 years. We described the association between use of K⁺ binders (Patiromer and sodium polystyrene sulfonate [SPS]) and renin-angiotensin-aldosterone system inhibitor (RAASi), on healthcare resource utilization (HRU). The study population consisted of Medicare Advantage patients with HK (K⁺ ≥ 5.0 mmol/L) in Optum’s Clinformatics^® Data Mart between 1/1/2016–12/31/2017. Patiromer and (SPS) initiators, and HK patients not exposed to a K⁺ binder (NoKb) were included. The index date was the date of the first K⁺ binder dispensing or HK diagnosis. Outcomes assessed at 6 months post-index were: (1) K⁺ binder utilization, (2) RAASi continuation, and (3) HRU (pre- vs post-index). HRU change was analyzed using McNemar’s statistical test. Study cohorts included 610 (patiromer), 5556 (SPS), and 21,282 (NoKb) patients. Overall baseline patient characteristics were: mean age 75 years; female 49%, low-income subsidy 29%, chronic kidney disease 48% (63% for patiromer cohort), and congestive heart failure 29%. At 6 months post-index, 28% (patiromer) and 2% (SPS) remained continuously exposed to the index K⁺ binder. RAASi continued for 78% (patiromer), 57% (SPS), and 57% (NoKb). The difference (pre- vs post-index) in hospitalized patients was: –9.4% (patiromer; P<0.05), –7.2% (SPS), and +16.8% (NoKb; P<0.001). Disparate K⁺ binder utilization patterns were observed. The majority of patiromer patients continued RAASi therapy while the percentage of SPS patients that continued RAASi therapy was lower, overlapping CIs were observed. Following continuous patiromer exposure, statistically significant reductions in hospital admissions and emergency department visits were observed, continuous SPS exposure observed no statistically significant reductions in either hospitalizations or ED visits, while NoKb patients with continuous exposure had statistically significant increases in both. Further research, with a larger sample size using comparative analytic methods, is warranted.

Patiromer for Treatment of Hyperkalemia in the Emergency Department: A Pilot Study

BACKGROUND

Hyperkalemia is common and potentially life threatening. Patiromer is a Food and Drug Administration (FDA)-cleared oral potassium binder effective in the chronic treatment of hyperkalemia.

OBJECTIVE

The objective was to investigate the potential efficacy and safety of oral patiromer in treating acute hyperkalemia in the emergency department (ED).

METHODS

This is a single-center, randomized, open-label convenience sample pilot study in an inner-city ED. Adult patients with end-stage renal disease and a serum potassium level of ≥ 6.0 mEq/L were randomized to standard of care (SOC) or one dose of 25.2 g oral patiromer plus SOC (PAT). Blood samples and electrocardiograms were collected at enrollment and at 1, 2, 4, and 6 hours thereafter. The primary outcome was the difference in potassium between groups at 6 hours. Secondary outcomes were the amount and number of times insulin and albuterol were given.

RESULTS

Thirty patients were included in the final analysis, 15 in each group. There were no differences in age, sex, or baseline serum potassium. There was no difference in mean serum potassium between SOC and PAT groups at 6 hours (6.32 mEq/L, confidence interval [CI] = 6.0 to 6.63 mEq/L vs. 5.81 mEq/L, CI = 5.48 to 6.14 mEq/L). However, 2 hours posttreatment the serum potassium of the PAT group was lower than SOC group (5.90 mEq/L, CI = 5.63 to 6.17 mEq/L vs. 6.51 mEq/L, CI = 6.25 to 6.78 mEq/L) and also 0.61 mEq/L lower than baseline. There were no differences in the amount or number of administrations of insulin or albuterol between groups, although the amount of albuterol used in the PAT group at 6 hours was lower but not significant (median, 0 mg vs. 12.5 mg; p = 0.097). There were no differences in adverse events between groups.

CONCLUSION

In this open-label pilot study of severe hyperkalemia, a single dose of 25.2 g of oral patiromer reduced serum potassium within 2 hours but did not show a difference at 6 hours. This is the first study showing that patiromer may have a role in the acute management of hyperkalemia; however, more rigorous studies are needed.

Boosting the Limited Use of Mineralocorticoid Receptor Antagonists Through New Agents for Hyperkalemia

Background:

Hyperkalemia is an important clinical problem that is associated with significant lifethreatening complications. Several conditions are associated with increased risk for hyperkalemia such as chronic kidney disease, diabetes mellitus, heart failure, and the use of renin-angiotensin-aldosterone system (RAAS) inhibitors.

Objective:

The purpose of this review is to present and critically discuss treatment options for the management of hyperkalemia.

Method:

A comprehensive review of the literature was performed to identify studies assessing the drug-induced management of hyperkalemia.

Results:

The management of chronic hyperkalemia seems to be challenging and includes a variety of traditional interventions, such as restriction in the intake of the dietary potassium, loop diuretics or sodium polystyrene sulfonate. In the last few years, several new agents have emerged as promising options to reduce potassium levels in hyperkalemic patients. Patiromer and sodium zirconium cyclosilicate 9 (ZS-9) have been examined in hyperkalemic patients and were found to be efficient and safe. Importantly, the efficacy of these novel drugs might allow the continuation of the use of RAAS inhibitors, morbidity- and mortality-wise beneficial class of drugs in the setting of chronic kidney disease and heart failure.

Conclusion:

Data support that the recently emerged patiromer and ZS-9 offer significant hyperkalemia-related benefits. Larger trials are needed to unveil the impact of these drugs in other patients’ subpopulations, as well.