Association of Prescription of Oral Sodium Polystyrene Sulfonate With Sorbitol in an Inpatient Setting With Colonic Necrosis: A Retrospective Cohort Study

Risk of Serious Adverse Gastrointestinal Events with Potassium Binders in Hospitalized Patients: A National Study

BACKGROUND

Concerns about serious adverse gastrointestinal (GI) events with sodium polystyrene sulfonate (SPS) led to development of two new potassium binders, patiromer and sodium zirconium cyclosilicate (SZC), for treatment of hyperkalemia.

OBJECTIVE

To compare risk of intestinal ischemia/thrombosis or other serious GI events associated with SPS, patiromer, or SZC in hospitalized patients.

DESIGN

Retrospective cohort study.

PARTICIPANTS

National sample of 3,144,960 veterans hospitalized 2016-2022 in the U.S. Department of Veterans Affairs Healthcare System.

MAIN MEASURES

Demographics, comorbidities, medications and outcomes were ascertained from the VA Corporate Data Warehouse. Exposures were SPS, patiromer, SZC. Outcomes were 30-day intestinal ischemia/thrombosis, and a composite of intestinal ischemia/thrombosis, peptic ulcer/perforation or bowel resection/ostomy.

KEY RESULTS

Potassium binders were used during 39,270 (1.3%) hospitalizations: SPS = 30,040 (1.0%), patiromer = 3,750 (0.1%), and SZC = 5,520 (0.2%). Intestinal ischemia/thrombosis occurred with 106/30,040 (0.4%) SPS, 12/3750 (0.3%) patiromer and 24/5520 (0.4%) SZC, vs. 6998/3,105,650 (0.2%) without potassium binder. Adjusted odds ratios (aOR) were 1.40 [95% CI, 1.16 to 1.69] with SPS, 1.36 [CI, 0.79 to 2.36] with patiromer, and 1.78 [CI, 1.21 to 2.63] with SZC exposures. Composite GI adverse events occurred with 754/30,040 (2.5%) SPS, 96/3750 (2.6%) patiromer, 2.6% SZC, vs. 144/5520 (2.4%) without binder; aOR were 1.00 [CI, 0.94 to 1.08] with SPS, 1.08 [CI, 0.89 to 1.32] with patiromer, and 1.08 [CI, 0.93 to 1.27] with SZC exposures. No statistical difference in intestinal ischemia/thrombosis between each new agent and SPS was seen (p = 0.274 for SPS vs. SZC; p = 0.916 for SPS vs. patiromer).

CONCLUSION

Risk of intestinal ischemia/thrombosis or other serious adverse GI events was low and did not differ across three potassium-binding drugs.

Aldosterone and Potassium in Heart Failure: Overcoming This Major Impediment in Clinical Practice

Aldosterone is a key regulator of fluid and electrolyte balance in the body. It is often dysregulated in heart failure (HF) and is a key driver of cardiac remodelling and worse clinical outcomes. Potassium regulation is essential for normal cardiac, gastrointestinal and neuromuscular function. Serum potassium fluctuations are largely determined by aldosterone, the final step of the renin-angiotensin-aldosterone system. Dyskalaemia (i.e. hypokalaemia and hyperkalaemia) is prevalent in HF because of the disease itself, its therapies and related comorbidities such as chronic kidney disease. Prognostic implications of abnormal serum potassium follow a U-shaped curve, where both hypokalaemia and hyperkalaemia are associated with adverse outcomes. Hypokalaemia is associated with increased mortality, starting from potassium <4.0 mmol/l but especially at potassium <3.5 mmol/l. Hyperkalaemia, along with increasing arrhythmia risk, limits the use of lifesaving renin-angiotensin- aldosterone system inhibitors, which may have long-term survival implications. The advent of novel potassium binders aims to manage chronic hyperkalaemia and may allow for uptitration and optimal dosing of guideline-recommended therapy. This review discusses the impacts of dyskalaemia in HF, along with management strategies, including the relevance of potassium binder use in optimising HF treatment. Current and potential future aldosterone-modulating therapies, such as non-steroidal mineralocorticoid receptor antagonists and aldosterone synthase inhibitors, are also discussed.

Sodium Polystyrene Sulfonate-Induced Massive Bowel Necrosis With Distant Extraintestinal Crystal Deposition: A Case Report and Review of the Literature

Sodium polystyrene sulfonate (SPS), a cation-exchange resin, has been a mainstay in long-term hyperkalemia management but is associated with significant gastrointestinal complications, particularly when used with sorbitol. The deposition of SPS crystals within the intestinal mucosa has been suggested to precipitate ischemia, necrosis, and ulcerations, ultimately leading to bowel perforation. This case report details a striking instance of massive bowel perforation subsequent to SPS administration, with accompanying findings of disseminated crystals in distant organs and tissues upon autopsy. Additionally, we provide a comprehensive review of the existing literature on this rare yet significant drug-induced side effect.

Therapeutic update on oral potassium exchange resin use in chronic kidney disease patients: a systematic review of randomized controlled clinical trials

Hyperkalemia is a common electrolyte disorder in patients with chronic kidney disease (CKD) that increases in prevalence with the decline of glomerular fltration rate (GFR). Another risk of hyperkalemia is the use of renin-angiotensin-aldosterone system inhibitors (RAASi) and/or mineralocorticoid receptor antagonists (MRAs) in managing CKD and proteinuria. The treatment of chronic hyperkalemia is challenging especially for outpatients. Treatment options for hyperkalemia include the potassium exchange resins of which two new potassium binders, Patiromer Sorbitex Calcium, and Sodium Zirconium Cyclosilicate (SZC) have demonstrated their clinical efficacy in reducing serum potassium with a positive safety profile. The old potassium exchange resin sodium polystyrene sulfonate (Kayexalate™) has some negative side effects including colonic necrosis, hypomagnesemia, and hypernatremia. In this review and literature search, we compare the available oral potassium exchange resins, highlight their advantages and disadvantages and comment on efficacy and safety parameters specifically in CKD patients.

Comprehensive analysis of sodium polystyrene sulfonate-induced colitis: A systematic review

BACKGROUND

Sodium polystyrene sulfonate (SPS) is commonly prescribed for the management of hyperkalemia, a critical electrolyte imbalance contributing to over 800000 annual visits to emergency departments.

AIM

To conduct a systematic review of documented cases of SPS-induced colitis and assess its associated prognosis.

METHODS

Following the PRISMA-P guidelines, our study employed Medical Subject Headings and Health Sciences Descriptors, skillfully combined using Boolean operators, to conduct comprehensive searches across various electronic databases, including Scopus, Web of Science, MEDLINE (PubMed), BIREME (Biblioteca Regional de Medicina), LILACS (Latin American and Caribbean Health Sciences Literature), SciELO (Scientific Electronic Library Online), Embase, and Opengray.eu. Language criteria were confined to English, Spanish, and Portuguese, with no limitations on the publication date. Additionally, we manually scrutinized the reference lists of retrieved studies. To present our findings, we utilized simple descriptive analysis.

RESULTS

Our search strategy yielded a total of 442 references. After rigorous evaluation, we included 51 references, encompassing 59 documented cases of colitis. Predominant clinical presentations included abdominal pain, observed in 35 (60.3%) cases, and bloating, reported in 18 (31%) cases. The most frequently affected sites of inflammation were the cecum, rectum, and small intestine, accounting for 31%, 25.8%, and 22.4% of cases, respectively. Colonoscopy findings were described in 28 (48.2%) cases, and 29 (50%) of patients required surgical intervention. Among the subset of patients for whom outcome data was available, 39 (67.2%) experienced favorable outcomes, while 12 (20.6%) unfortunately succumbed to the condition. The mean time required for resolution was 36.7 d, with a range spanning from 1 to 120 d.

CONCLUSION

SPS demonstrates the capacity to effectively lower serum potassium levels within 24 h. However, this benefit is not without the risk of bowel injury. Our study highlights the absence of high-quality data pertaining to the incidence of adverse events associated with SPS usage, making it challenging to determine whether the potential risks outweigh the benefits. However, a significant mortality rate related to SPS-induced colitis was noted. Future investigations should prioritize randomized controlled trials with a sufficiently large patient cohort to ascertain the true utility and safety profile of this medication.

Hyperkalemia in chronic kidney disease: a focus on potassium lowering pharmacotherapy

INTRODUCTION

Hyperkalemia is one of the most common electrolyte disorders in chronic kidney disease (CKD) and is associated with serious adverse outcomes. Hyperkalemia risk is even greater when CKD patients also have additional predisposing conditions such as diabetes or heart failure. Renin-angiotensin-aldosterone-system blockers are first-line treatments for cardio- and nephroprotection, but their use is often limited due to K+ elevation, resulting in high rates of discontinuation.

AREAS COVERED

This article provides an overview of factors interfering with K+ homeostasis and discusses recent data on newer therapeutic agents used for the treatment of hyperkalemia. A detailed literature search was performed in two major databases (PubMed/MEDLINE and Scopus) up to April 2023.

EXPERT OPINION

Major clinical trials have tested new and promising kidney protective therapies such as sodium/glucose-cotransporter-2 inhibitors and mineralocorticoid-receptor-antagonists, with promising results. Until recently, the only treatment option for hyperkalemia was the cation-exchanging resin sodium-polystyrene-sulfonate. However, despite its common use, the efficacy and safety data of this drug in the long-term management of hyperkalemia are scarce. During the last decade, two novel orally administered K+-exchanging compounds (patiromer and sodium-zirconium-cyclosilicate) have been approved for the treatment of adults with hyperkalemia, as they both effectively reduce elevated serum K+ and maintain chronically K+ balance within the normal range with an excellent tolerability and no serious adverse events.

Potassium homeostasis - Physiology and pharmacology in a clinical context

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

Pharmacological strategies to manage hyperkalaemia: out with the old, in with the new? Not so fast…

Since the 1950s, sodium polystyrene sulphonate (SPS) has been the dominant cation exchange agent prescribed for hyperkalaemia. Clinicians have had plenty of time to learn of SPS's advantages and limitations. The demands of drug regulatory agencies regarding the incorporation of medications into the market were not so stringent then as they are today, and the efficacy and safety of SPS have been questioned. In recent years, two novel cation exchangers, patiromer and sodium zirconium cyclosilicate, have received (or are in the process of receiving) regulatory approval in multiple jurisdictions globally, after scrutiny of carefully conducted trials regarding their short-term and mid-term efficacy. In this debate, we defend the view that all three agents are likely to have similar efficacy. Harms are much better understood for SPS than for newer agents, but currently there are no data to suggest that novel agents are safer than SPS. Drug choices need to consider costs, access and numbers-needed-to-treat to prevent clinically important events; for potassium exchangers, we need trials directly examining clinically important events.

Adverse Gastrointestinal Events With Sodium Polystyrene Sulfonate Use in Patients on Maintenance Hemodialysis: An International Cohort Study

Background

There are concerns regarding the gastrointestinal (GI) safety of sodium polystyrene sulfonate (SPS), a medication commonly used in the management of hyperkalemia.

Objective

To compare the risk of GI adverse events among users versus non-users of SPS in patients on maintenance hemodialysis.

Design

International prospective cohort study.

Setting

Seventeen countries (Dialysis Outcomes and Practice Patterns Study [DOPPS] phase 2-6 from 2002 to 2018).

Patients

50 147 adults on maintenance hemodialysis.

Measurements

An adverse GI event defined by a GI hospitalization or GI fatality with SPS prescription compared with no SPS prescription.

Methods

Overlap propensity score-weighted Cox models.

Results

Sodium polystyrene sulfonate prescription was present in 13.4% of patients and ranged from 0.42% (Turkey) to 20.6% (Sweden) with 12.5% use in Canada. A total of 935 (1.9%) adverse GI events (140 [2.1%] with SPS, 795 [1.9%] with no SPS; absolute risk difference 0.2%) occurred. The weighted hazard ratio (HR) of a GI event was not elevated with SPS use compared with non-use (HR = 0.93, 95% confidence interval = 0.83-1.6). The results were consistent when examining fatal GI events and/or GI hospitalization separately.

Limitations

Sodium polystyrene sulfonate dose and duration were unknown.

Conclusions

Sodium polystyrene sulfonate use in patients on hemodialysis was not associated with a higher risk of an adverse GI event. Our findings suggest that SPS use is safe in an international cohort of maintenance hemodialysis patients.

Hyperkalemia: Prevalence, Predictors and Emerging Treatments

It is well established that an elevated potassium level (hyperkalemia) is associated with a risk of adverse events including morbidity, mortality and healthcare system cost. Hyperkalemia is commonly encountered in many chronic conditions including kidney disease, diabetes and heart failure. Furthermore, hyperkalemia may result from the use of renin-angiotensin-aldosterone system inhibitors (RAASi), which are disease-modifying treatments for these conditions. Therefore, balancing the benefits of optimizing treatment with RAASi while mitigating hyperkalemia is crucial to ensure patients are optimally treated. In this review, we will briefly discuss the definition, causes, epidemiology and consequences of hyperkalemia. The majority of the review will be focused on management of hyperkalemia in the acute and chronic setting, emphasizing contemporary approaches and evolving data on the relevance of dietary restriction and the use of novel potassium binders.

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.

Sodium Polystyrene Sulfonate-Induced Gastric Pneumatosis: A Rare Side Effect

Kayexalate has been used in the USA since 1975 for the treatment of hyperkalemia. Prior case reports have shown that sorbitol added to kayexalate has been known to cause rare side effects of colonic necrosis. We present a unique case report of gastric pneumatosis as a complication of kayexalate.

Risk of Intestinal Necrosis With Sodium Polystyrene Sulfonate: A Systematic Review and Meta-analysis

BACKGROUND

Reports of severe gastrointestinal side effects associated with sodium polystyrene sulfonate (SPS), particularly intestinal necrosis, have led some to recommend costlier alternative medications. No prior systematic review has included studies with controls reporting intestinal necrosis rates associated with SPS.

METHODS

A systematic literature search was conducted using Cochrane Library, Embase, Medline, Google Scholar, PubMed, Scopus, and Web of Science Core Collection from database inception through October 4, 2020. We included any clinical trial, cohort, or case-control study reporting an association between SPS and intestinal necrosis or severe gastrointestinal side effects.

RESULTS

Six studies including 26,716 patients treated with SPS with controls met inclusion criteria. The pooled odds ratio (OR) of intestinal necrosis was 1.43 (95% CI, 0.39-5.20). The pooled hazard ratio (HR) for intestinal necrosis from the two studies that performed survival analysis was 2.00 (95% CI, 0.45-8.78). The pooled HR for the composite outcome of severe gastrointestinal adverse events was 1.46 (95% CI, 1.01-2.11).

CONCLUSION

Based on our review of six studies, the risk of intestinal necrosis with SPS is not statistically greater than controls, although there was a statistically significantly increased risk for the composite outcome of severe gastrointestinal side effects based on two studies. Because of the risk of bias from potential confounding and selective reporting, the overall strength of evidence to support an association between SPS and intestinal necrosis or other severe gastrointestinal side effects is low. PROSPERO registration CRD42020213119.

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).

Adverse gastrointestinal events with sodium polystyrene sulphonate and calcium polystyrene sulphonate use in dialysis patients: a nationwide registry study

INTRODUCTION

Sodium polystyrene sulphonate (SPS) and calcium polystyrene sulphonate (CPS) are commonly used cation-exchange resins for the treatment and control of hyperkalaemia. However, their use (particularly SPS) has been limited by reports of adverse gastrointestinal (GI) events. The safety of these compounds in patients undergoing dialysis requires larger investigation.

AIMS

To study the occurrence of adverse GI events (occlusion, perforation, thrombosis/ischaemia) in the periods of SPS or CPS exposition versus the periods without exposition in dialysis patients.

METHODS

Dialysis patients were extracted from the French National Registry and merged with the French hospital discharge database (between 2006 and 2017). For our primary analysis, we used patients who had any claim of SPS use (n = 43 771). Time-varying Cox models, negative binomial regression and pre- versus post-treatment average treatment effects.

RESULTS

The mean age was 66 ± 15 years, 37% were female and 92% were undergoing haemodialysis. Over a 1-year follow-up, patients on periods with SPS (on-SPS) did not present an increased risk of adverse GI events versus the periods without SPS (off-SPS):  incidence rate (IR) (per 1000 person years) = 7.4 (6.4-8.7) versus 9.5 (8.1-11.0); adjusted hazard ratio (HR) (95% CI) = 0.81 (0.60-1.09), P = 0.17. Patients exposed to SPS did not experience a higher rate of adverse GI events in the year after SPS initiation versus the year before SPS initiation; P-value for parallel trend = 0.87. Patients on-CPS also did not show an increased risk of adverse GI events versus off-CPS: IR (per 1000 py) = 8.6 (5.1-11.9) versus 7.8 (5.1-11.9); adjusted HR (95% CI) = 0.76 (0.31-1.80), P = 0.52. The rates of adverse GI events in the periods on and off exposure were also similar over a follow-up of 5 years.

CONCLUSION

Our large, nationwide study shows that the incidence of adverse GI events in patients undergoing dialysis was low and that neither the use of SPS nor CPS was associated with increased GI events risk.

Small crystals with severe consequences

We present the case of a 23-year-old patient who developed a severe gastric ischemia after the ingestion of a single dose of sodium polystyrene sulfonate (SPS) orally. Emergency surgery confirmed extensive full thickness gastric necrosis, prompting a total gastrectomy. Histopathology showed kayexalate crystals in the gastric wall, suggesting SPS-related ischemic gastritis. After radical resection of the affected stomach, this young patient was able to fully recover. Although effective, the widespread use of SPS to treat hyperpotassemia remains a debated topic because of rare but serious adverse events like the forming of kayexalate crystal residues in the gastrointestinal tract. These crystal residues are mostly found in the large intestine and can lead to ulceration and necrosis. Physicians need to be aware of this rare but potentially devastating adverse effect of SPS ingestion.

Growth characteristics of human bone marrow mesenchymal stromal cells at cultivation on synthetic polyelectrolyte nanofilms in vitro

This study examines the adhesive properties and cytotoxicity of polyelectrolyte nanofilms from polyethyleneimine (PEI), polyallylamine hydrochloride (PAH) and sodium polystyrene sulfonate (PSS) on human bone marrow mesenchymal stromal cells (h-MSCs) and mouse adipose tissue (m-MSC) in vitro. Films are formed on 24- and 96-well culture plates in the combinations: PEI, PAH, PEI-PSS, PEI-PSS-PAH, PEI-PSS-PEI. An analysis of the culture results show that direct contact of h-MSCs with the PEI surface promotes adhesion (93–95% of adhesive cells versus 40% in the control). On the PEI surface, h-MSCs are evenly distributed, form colonies and 80% monolayer after 72 h of culture, as in the control on culture plastic. On nanofilms from PAH and PEI-PSS-PAH, cells grow in the form of rosette-like colonies with long and thin processes similar to neurites. The cytotoxic properties of PSS were revealed in direct contact with h-MSCs (more than 40% of nonviable cells with damaged plasma membranes). On the PSS surface, cells lost their adhesiveness. To culture and stably grow the cell mass of h-MSCs, it is better to use monolayer nanofilms made of highly adhesive and non-toxic PEI polyelectrolyte, which can bind the growth factors of blood serum and platelet lysate, ensuring the growth of h-MSCs under in vitro deprivation conditions.

Polysulfonate Resins in Hyperkalemia: A Systematic Review

BACKGROUND

Hyperkalemia is a potentially life-threatening electrolyte abnormality defined as a serum potassium above the lab reference range (usually >5.0-5.5 mEq/L). Polystyrene resins, including sodium polystyrene sulfonate (SPS) and calcium polystyrene sulfonate (CPS), have long been used to treat hyperkalemia. Sodium polystyrene sulfonate/calcium polystyrene sulfonate act by exchanging a cation for potassium within the intestinal lumen. While SPS and CPS have been available since the 1960s, there are rising concerns about the validity of the data supporting its use and about serious adverse gastrointestinal effects.

OBJECTIVE

The objective of this systematic review was to quantify the efficacy and safety of polystyrene sulfonate resins (SPS/CPS) in the treatment of adults with hyperkalemia. This review focuses on the randomized control trial (RCT), interventional non-RCT, and observational data available on SPS/CPS use.

DESIGN

Systematic review.

SETTING

Any country of origin. Both inpatient and outpatient settings.

PATIENTS

Adults with hyperkalemia treated with polystyrene sulfonate resins.

MEASUREMENTS

The primary outcome was change in serum potassium. The secondary outcomes included adverse effects of SPS/CPS and prevention of recurrent hyperkalemia.

METHODS

We conducted a systematic review using Cochrane Library, EMBASE (1947-2019), and Medline (1946-2019) databases. Literature reviews, systematic reviews, case studies, case series, and editorial pieces were excluded. Included studies were assessed for risk of bias.

RESULTS

Four RCTs, 21 observational studies, and 5 quasi-experimental trials were included. A total of 212 351 patients were included. Two thousand and fifty-eight patients were studied for the primary outcome and 210 293 patients were studied for the secondary outcomes. Study designs were heterogeneous and not amenable to meta-analysis. Most studies included nonhemodialysis outpatients older than 65 years. Of the included studies, 22/25 (88%) demonstrated a reduction of serum potassium >0.5 mEq/L over the study period. The magnitude of reduction in serum potassium of potassium resin compared with placebo or matched controls in the 3 low-risk studies identified was 0.14 to 1.04 mEq/L. However, each study used different dosing regimens. Ten of 22 studies reported the effects of polystyrene resins on serum potassium within 24 hours. A few high-quality observational studies suggest an increased risk of serious adverse gastrointestinal events with a relative risk of 2.10 and a hazard ratio of 1.25 to 1.94; however, the absolute risk remains low. The incidence of adverse gastrointestinal events is 16 to 23 events per 1000 person-years.

LIMITATIONS

We acknowledge several limitations in this study. Case studies and case series were excluded from the search results. Large case series may have been excluded despite having comparable sample sizes to studies included due to lack of a comparator and calculated estimates. Due to the heterogeneity of the studies, the data were unable to be meta-analyzed and as such the potassium-lowering effect of polystyrene sulfonate resins remains founded on small studies with potential confounders.

CONCLUSIONS

This systematic review demonstrates a continued lack of high-quality evidence for the use of SPS/CPS in hyperkalemia. Studies investigated highly variable timelines and the most robust evidence for SPS/CPS use is in chronic hyperkalemia. While the absence of high-quality evidence does not exclude the possibility of benefit, prescribers must understand that the use of SPS/CPS in acute hyperkalemia is not supported by high-quality evidence.

TRIAL REGISTRATION

The protocol for this systematic review was not registered.

Initiation of sodium polystyrene sulphonate and the risk of gastrointestinal adverse events in advanced chronic kidney disease: a nationwide study

BACKGROUND

Despite long-standing clinical use of sodium polystyrene sulphonate (SPS) for hyperkalaemia management in chronic kidney disease (CKD), its safety profile remains poorly investigated.

METHODS

We undertook an observational analysis of nephrology-referred adults with incident CKD Stage 4+ in Sweden during 2006-16 and with no previous SPS use. We studied patterns of use and adverse events associated to SPS initiation during follow-up. Patterns of SPS use were defined by chronicity of treatment and by prescribed dose. We estimated hazard ratios (HRs) and 95% confidence intervals (CIs) associated with SPS initiation (time-varying exposure) for the risk of severe (intestinal ischaemia, thrombosis or ulceration/perforation) and minor (de novo dispensation of laxatives or anti-diarrheal drugs) gastrointestinal (GI) events.

RESULTS

Of 19 530 SPS-naïve patients with CKD, 3690 initiated SPS during follow-up. A total of 59% took SPS chronically, with an average of three dispensations/year. The majority (85%) were prescribed lower dosages than specified on the product label. During follow-up, 202 severe and 1149 minor GI events were recorded. SPS initiation was associated with a higher incidence of severe adverse events [adjusted HR 1.25 95% CI 1.05-1.49)], particularly in those receiving per label doses [1.54 (1.09-2.17)] and mainly attributed to ulcers and perforations. SPS initiation was also associated with higher incidence of minor GI events [adjusted HR 1.11 (95% CI 1.03-1.19)], regardless of dose, and mainly accounted for by de novo dispensation of laxatives.

CONCLUSIONS

Initiation of SPS in patients with advanced CKD is associated with a higher risk of severe GI complications as well as the initiation of GI-related medications, particularly when prescribed at per label doses.

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.

Treating potassium disturbances: kill the killers but avoid overkill

OBJECTIVES

In this publication, we review the definitions, symptoms, causes, differential diagnoses and therapies of hypokalemia and hyperkalemia.

METHODS

Comprehensive tables and diagnostic algorithms are provided when appropriate.

RESULTS AND CONCLUSIONS

Although both hypokalemia and hyperkalemia may be life-threatening, this is essentially the case with severe changes (serum potassium < 2.5 or > 6.5 mmol/L), the presence of symptoms or electrocardiographic deviations, the association with aggravating factors (e.g. digitalis intake) and/or rapid acute changes. Only these truly need an emergency therapeutic approach. In all other cases, a careful consideration of the causes and their correction should prevail over additional approaches to modify serum potassium concentration. Although most therapeutic approaches to both hypokalemia and hyperkalemia have been well established since many years, recently two new intestinal potassium binders have been introduced on the market. It remains to be elucidated whether these drugs truly have an additional role on top of the existing treatments.

Risk of Hospitalization for Serious Adverse Gastrointestinal Events Associated With Sodium Polystyrene Sulfonate Use in Patients of Advanced Age

IMPORTANCE

Sodium polystyrene sulfonate is commonly prescribed for the treatment of hyperkalemia. Case reports of intestinal injury after administration of sodium polystyrene sulfonate with sorbitol resulted in a US Food and Drug Administration warning and discontinuation of combined 70% sorbitol-sodium polystyrene sulfonate formulations. There are ongoing concerns about the gastrointestinal (GI) safety of sodium polystyrene sulfonate use.

OBJECTIVE

To assess the risk of hospitalization for adverse GI events associated with sodium polystyrene sulfonate use in patients of advanced age.

DESIGN, SETTING, AND PARTICIPANTS

Population-based, retrospective matched cohort study of eligible adults of advanced age (≥66 years) dispensed sodium polystyrene sulfonate from April 1, 2003, to September 30, 2015, in Ontario, Canada, with maximum follow-up to March 31, 2016. Initial data analysis was conducted from August 1, 2018, to October 3, 2018; revision analysis was conducted from February 25, 2019, to April 2, 2019. Cox proportional hazards regression models were used to examine the association of sodium polystyrene sulfonate use with a composite of GI adverse events compared with nonuse that was matched via a high-dimensional propensity score. Additional analyses were limited to a subpopulation with baseline laboratory values of estimated glomerular filtration rate and serum potassium level.

EXPOSURE

Dispensed sodium polystyrene sulfonate in an outpatient setting.

MAIN OUTCOMES AND MEASURES

The primary outcome was a composite of adverse GI events (hospitalization or emergency department visit with intestinal ischemia/thrombosis, GI ulceration/perforation, or resection/ostomy) within 30 days of initial sodium polystyrene sulfonate prescription.

RESULTS

From a total of 1 853 866 eligible adults, 27 704 individuals were dispensed sodium polystyrene sulfonate (mean [SD] age, 78.5 [7.7] years; 54.7% male), and 20 020 sodium polystyrene sulfonate users were matched to 20 020 nonusers. Sodium polystyrene sulfonate use compared with nonuse was associated with a higher risk of an adverse GI event over the following 30 days (37 events [0.2%]; incidence rate, 22.97 per 1000 person-years vs 18 events [0.1%]; incidence rate, 11.01 per 1000 person-years) (hazard ratio, 1.94; 95% CI, 1.10-3.41). Results were consistent in additional analyses, including the subpopulation with baseline laboratory values (hazard ratio, 2.91; 95% CI, 1.38-6.12), and intestinal ischemia/thrombosis was the most common type of GI injury.

CONCLUSIONS AND RELEVANCE

The use of sodium polystyrene sulfonate is associated with a higher risk of hospitalization for serious adverse GI events. These findings require confirmation and suggest caution with the ongoing use of sodium polystyrene sulfonate.

Single-dose sodium polystyrene sulfonate for hyperkalemia in chronic kidney disease or end-stage renal disease

BACKGROUND

The use of sodium polystyrene sulfonate (SPS) for the treatment of hyperkalemia lacks sufficient efficacy data in patients with chronic kidney disease (CKD) and end-stage renal disease (ESRD); however, use remains widespread. Recent evidence suggests that this population may be at risk for serious gastrointestinal adverse effects with SPS. Methods. We conducted a single-center retrospective cohort study. Adult patients with CKD Stages 4, 5, or ESRD maintained on renal replacement therapy with serum potassium >5 mEq/L and receipt of SPS were screened for inclusion. Our primary outcome was decrease in potassium within 24 h post-30 g oral SPS suspended in 33% sorbitol. Secondary outcomes included decrease in potassium within 24 h from 15 or 30 g SPS doses and gastrointestinal adverse events.

RESULTS

Of 596 records, 114 were included for analysis. At the first serum potassium level within 24 h post-30 g oral SPS the median potassium decrease was 0.8 mEq/L [interquartile range (IQR) 0.4-1.1; P < 0.001]. At the first potassium level within 24 h post-15 or 30 g SPS, the median potassium decrease was 0.7 mEq/L (IQR 0.4-1.0; P < 0.001]. Post-SPS potassium levels occurred 14-16 h post-SPS. Gastrointestinal side effects occurred within 30 days of SPS in 5% of patients, although only two cases were classified as possibly associated.

CONCLUSIONS

The use of single-dose SPS monotherapy resulted in a significant decrease in serum potassium levels within 24 h in patients with CKD Stage 4, 5, or ESRD. However, it remains unclear if SPS is associated with an increased risk of gastrointestinal injury in this population.

Emergency Department Management of Acute Kidney Injury, Electrolyte Abnormalities, and Renal Replacement Therapy in the Critically Ill

Acute kidney injury (AKI) is a common sequela of critical illness. Clinical manifestation of AKI varies and can include electrolyte abnormalities, anion gap, or non-anion-gap metabolic acidosis. Treatment strategies require careful identification of the cause of the AKI, relying on both clinical history and laboratory data. Once the cause has been identified, treatment can then target the underlying cause and avoid further insults. Conservative management should first be attempted for patients with AKI. If conservative management fails, renal replacement therapy or hemodialysis can be used.

Medication Safety Principles and Practice in CKD

Ensuring patient safety is a priority of medical care because iatrogenic injury has been a primary concern. Medications are an important source of medical errors, and kidney disease is a thoroughfare of factors threatening safe administration of medicines. Principal among these is reduced kidney function because almost half of all medications used are eliminated via the kidney. Additionally, kidney patients often suffer from multimorbidity, including diabetes, hypertension, and heart failure, with a range of prescribers who often do not coordinate treatments. Patients with kidney disease are also susceptible to further kidney injury and metabolic derangements from medications, which can worsen the disease. In this review, we will present the key issues and threats to safe medication use in kidney disease, with a focus on predialysis CKD, as the scope of medication safety in ESKD and transplantation are unique and deserve their own consideration. We discuss drugs that need to be avoided or dose modified, and review the complications of a range of medications routinely administered in CKD, as these also call for cautious use.

Deleting Death and Dialysis: Conservative Care of Cardio-Vascular Risk and Kidney Function Loss in Chronic Kidney Disease (CKD)

The uremic syndrome, which is the clinical expression of chronic kidney disease (CKD), is a complex amalgam of accelerated aging and organ dysfunctions, whereby cardio-vascular disease plays a capital role. In this narrative review, we offer a summary of the current conservative (medical) treatment options for cardio-vascular and overall morbidity and mortality risk in CKD. Since the progression of CKD is also associated with a higher cardio-vascular risk, we summarize the interventions that may prevent the progression of CKD as well. We pay attention to established therapies, as well as to novel promising options. Approaches that have been considered are not limited to pharmacological approaches but take into account lifestyle measures and diet as well. We took as many randomized controlled hard endpoint outcome trials as possible into account, although observational studies and post hoc analyses were included where appropriate. We also considered health economic aspects. Based on this information, we constructed comprehensive tables summarizing the available therapeutic options and the number and kind of studies (controlled or not, contradictory outcomes or not) with regard to each approach. Our review underscores the scarcity of well-designed large controlled trials in CKD. Nevertheless, based on the controlled and observational data, a therapeutic algorithm can be developed for this complex and multifactorial condition. It is likely that interventions should be aimed at targeting several modifiable factors simultaneously.

The Successful Treatment of Sodium Polystyrene Sulfonate-induced Enteritis Diagnosed by Small Bowel Endoscopy

Sodium polystyrene sulfonate (SPS: Kayexalate^®) is an ion-exchange resin used to treat hyperkalemia in patients with chronic kidney disease. It is known that this resin sometimes causes colonic necrosis and perforation, but there are few reports about small bowel necrosis associated with SPS. We herein report the case of a patient who developed SPS-induced small bowel necrosis, which was diagnosed based on the examination of a small bowel endoscopic biopsy specimen. The SPS-induced small bowel necrosis was resistant to conservative treatment including the cessation of SPS, and finally required surgical bowel resection.

Hyperkalemia in the Hypertensive Patient

PURPOSE OF REVIEW

Hyperkalemia develops in a patient with systemic arterial hypertension (HTN) if one or more risk factors are present, namely chronic kidney disease (CKD) (especially severe stage 4-5 CKD), diabetes mellitus (DM), heart failure (HF), or pharmacological therapies that interfere with potassium homeostasis, mainly through renin-angiotensin-aldosterone inhibition (RAASi). Hyperkalemia is a considerable reason of morbidity (emergency department (ED) visits and hospitalizations) and portends a higher mortality risk in patients at risk; for instance, hyperkalemia increases the risk of mortality within 1 day of a hyperkalemic event. This review aims to identify the risk factors for high-serum potassium, highlight the risk versus benefit of RAASi in certain patient populations, and outline preventive as well as therapeutic strategies for hyperkalemia.

RECENT FINDINGS

A growing body of evidence supports the safety and efficacy of cation-exchange resins, patiromer, or sodium zirconium cyclosilicate, in patients with a compelling indication for RAASi, yet in whom such therapy was complicated by hyperkalemia, allowing these patients to benefit from continued RAASi therapy. In summary, novel cation exchange polymers present the clinician with a new and safe strategy to address hyperkalemia in patients with a compelling indication for ongoing RAASi therapy instead of withdrawal of such therapy.

Revisiting RAAS blockade in CKD with newer potassium-binding drugs

Among patients with proteinuric chronic kidney disease (CKD), current guideline recommendations mandate the use of agents blocking the renin angiotensin aldosterone system (RAAS) as first-line antihypertensive therapy based on randomized trials demonstrating that RAAS inhibitors are superior to other antihypertensive drug classes in slowing nephropathy progression to end-stage renal disease. However, the opportunities for adequate RAAS blockade in CKD are often limited, and an important impediment is the risk of hyperkalemia, especially when RAAS inhibitors are used in maximal doses or are combined. Accordingly, a large proportion of patients with proteinuric CKD may not have the anticipated renoprotective benefits since RAAS blockers are often discontinued due to incident hyperkalemia or are administered at suboptimal doses for fear of the development of hyperkalemia. Two newer potassium binders, patiromer and sodium zirconium cyclosilicate (ZS-9), have been shown to effectively and safely reduce serum potassium levels and maintain long-term normokalemia in CKD patients receiving background therapy with RAAS inhibitors. Whether these novel potassium-lowering therapies can overcome the barrier of hyperkalemia and enhance the tolerability of RAAS inhibitor use in proteinuric CKD awaits randomized trials.

Evaluation of the tolerability and efficacy of sodium polystyrene sulfonate for long-term management of hyperkalemia in patients with chronic kidney disease

PURPOSE

Sodium polystyrene sulfonate (SPS) is a cation-exchanging resin that has been widely used for several decades as first-line therapy of mild chronic hyperkalemia in patients with chronic kidney disease (CKD). However, evidence to prove the long-term tolerability and efficacy of SPS for the treatment of this condition is still missing.

METHODS

In this retrospective, observational study, we enrolled 26 outpatients with stages 3-4 CKD who received oral therapy with low-dose SPS for mild chronic hyperkalemia in the Outpatient Nephrology clinic of our Department during 2010-2016. We obtained medical records on side effects potentially attributable to SPS use, and we analyzed the changes in serum electrolytes before and after the initiation of SPS therapy.

RESULTS

Serum potassium levels fell from 5.9 ± 0.4 to 4.8 ± 0.5 mmol/l (P < 0.001) over a median follow-up of 15.4 months (range 3-27 months). SPS use was associated with a slight, but significant elevation in serum sodium levels (139.5 ± 2.9 vs 141.2 ± 2.4, P = 0.006), whereas serum calcium and phosphate remained unchanged before and after the initiation of SPS. We recorded ten episodes of recurrent serum potassium elevation ≥ 5.5 mmol/l, none of which required hospitalization or acute dialysis. No episode of colonic necrosis or any other serious drug-related adverse event was observed. SPS therapy was well-tolerated, since only 1 out of 26 patients discontinued SPS at 3 months due to gastrointestinal intolerance.

CONCLUSION

This study suggests that low-dose SPS is well-tolerated and can effectively normalize elevated serum potassium over several weeks in CKD outpatients with mild chronic 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.

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.

Treatment of Severe Hyperkalemia: Confronting 4 Fallacies

Severe hyperkalemia is a medical emergency that can cause lethal arrhythmias. Successful management requires monitoring of the electrocardiogram and serum potassium concentrations, the prompt institution of therapies that work both synergistically and sequentially, and timely repeat dosing as necessary. It is of concern then that, based on questions about effectiveness and safety, many physicians no longer use 3 key modalities in the treatment of severe hyperkalemia: sodium bicarbonate, sodium polystyrene sulfonate (Kayexalate [Concordia Pharmaceuticals Inc., Oakville, ON, Canada], SPS [CMP Pharma, Farmville, NC]), and hemodialysis with low potassium dialysate. After reviewing older reports and newer information, I believe that these exclusions are ill advised. In this article, I briefly discuss the treatment of severe hyperkalemia and detail why these modalities are safe and effective and merit inclusion in the treatment of severe hyperkalemia.

Potassium: friend or foe?

The kidney plays an essential role in maintaining homeostasis of ion concentrations in the blood. Because the concentration gradient of potassium across the cell membrane is a key determinant of the membrane potential of cells, even small deviations in serum potassium level from the normal setpoint can lead to severe muscle dysfunction, resulting in respiratory failure and cardiac arrest. Less severe hypo- and hyperkalemia are also associated with morbidity and mortality across various patient populations. In addition, deficiencies in potassium intake have been associated with hypertension and adverse cardiovascular and renal outcomes, likely due in part to the interrelated handling of sodium and potassium by the kidney. Here, data on the beneficial effects of potassium on blood pressure and cardiovascular and renal outcomes will be reviewed, along with the physiological basis for these effects. In some patient populations, however, potassium excess is deleterious. Risk factors for the development of hyperkalemia will be reviewed, as well as the risks and benefits of existing and emerging therapies for 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.

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

Background

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

Methods

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

Results

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

Conclusion

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

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.

Total colectomy for colon perforation after kayexalate administration: a case report and literature review of a rare complication

Kayexalate is an ion exchange resin that is commonly used to acutely treat patients with hyperkalemia. Bowel ulceration and necrosis is a rare and uncommonly recognized complication of kayexalate administration. More often, concomitant administration with sorbitol is reported to damage the bowel; however, there are reports of kayexalate administration causing bowel necrosis without sorbitol. We present a case of a critically ill patient who underwent total colectomy for colonic necrosis secondary to oral kayexalate administration that was not recognized until late in the pathologic process. We also review the literature to further investigate this progression.

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

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

The Unappreciated Role of Extrarenal and Gut Sensors in Modulating Renal Potassium Handling: Implications for Diagnosis of Dyskalemias and Interpreting Clinical Trials

In addition to the classic and well-established "feedback control" of potassium balance, increasing investigative attention has focused on a novel and not widely recognized complementary regulatory paradigm for maintaining potassium homeostasis-the "feed-forward control" of potassium balance. This regulatory mechanism, initially defined in rumen, has recently been validated in normal human subjects. Studies are being conducted to determine the location for this putative potassium sensor and to evaluate potential signals, which might increase renal potassium excretion. Awareness of this more updated integrative control mechanism for potassium homeostasis is ever more relevant today, when the medical community is increasingly focused on the challenges of managing the hyperkalemia provoked by renin-angiotensin-aldosterone system inhibitors (RAASis). Recent studies have demonstrated a wide gap between RAASi prescribing guidelines and real-world experience and have highlighted that this gap is thought to be attributable in great part to hyperkalemia. Consequently we require a greater knowledge of the complexities of the regulatory mechanisms subserving potassium homeostasis. Sodium polystyrene sulfonate has long been the mainstay for treating hyperkalemia, but its administration is fraught with challenges related to patient discomfort and colonic necrosis. The current and imminent availability of newer potassium binders with better tolerability and more predictive dose-response potassium removal should enhance the management of hyperkalemia. Consequently it is essential to better understand the intricacies of mammalian colonic K+ handling. We discuss colonic transport of K+ and review evidence for potassium (BK) channels being responsible for increased stool K+ in patients with diseases such as ulcerative colitis.

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.