Patiromer in patients with kidney disease and hyperkalemia receiving RAAS inhibitors

An electronic alert to decrease Kayexalate ordering

Important safety concerns have recently emerged regarding the use of sodium polystyrene sulfonate (Kayexalate), a cation-exchange resin commonly used for the treatment of hyperkalemia. We implemented an electronic alert system at a tertiary care academic medical center to warn providers of the safety concerns of Kayexalate. We assessed the number of Kayexalate prescriptions per month, as well as the number of grams of Kayexalate ordered per month, one year before versus one year after implementing the alert. The mean (±SD) number of Kayexalate orders decreased from 123 (±12) to 76 (±14) orders/month (38% absolute reduction, p < 0.001) after implementing the alert. Additionally, the mean (±SD) amount of Kayexalate prescribed decreased from 3332 (±329) to 1885 (±358) g/month (43% absolute reduction, p < 0.001). We conclude that an electronic alert is an effective tool to decrease Kayexalate ordering.

Optimizing dialysate potassium

Potassium shifts in thrice weekly HD patients are likely a reversible cause of arrhythmia and sudden cardiac death. In general, a dialysate potassium <2.0 mmol/L should be avoided, and many patients with dialysate potassium of 2 mmol/L could safely be adjusted upwards. The ideal predialysis serum potassium should be around 5.0 mmol/L. Trends in serum potassium and not single values, should inform chronic changes of dialysate potassium prescription. Atypical values should be dealt with as a one off, but should not lead to chronic bath changes. Referral to a renal dietician for counseling to limit dietary potassium intake is vital to prevent recurrence of these atypical episodes. Finally, facilities should develop and implement a formal and reliable way to alert the physician about possible potassium bath mismatching. This facility level approach works best if a policy is developed and endorsed by all involved stakeholders.

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.

Weight-based insulin dosing for acute hyperkalemia results in less hypoglycemia

Hyperkalemia treatment with intravenous insulin has been associated with hypoglycemia. This single-center, retrospective study compared the effects on hypoglycemia between weight-based insulin dosing (0.1 U/kg of body weight up to a maximum of 10 U) compared to standard flat doses of 10 U among patients weighing less than 95 kg. Of the 132 charts randomly selected for review, hypoglycemic events (blood glucose <70 mg/dL) were reduced from 27.3% in the 10-U group to 12.1% in the weight-based group (P = 0.05). The number of affected patients was reduced with 19.7% in the 10-U group and 10.6% in the weight-based group (P = 0.22). The potassium-lowering effects of these 2 strategies were similar between groups. Female patients and those with baseline glucose values <140 mg/dL were at increased risk for hypoglycemia. Weight-based insulin dosing (0.1 U/kg) for acute hyperkalemia therapy resulted in less hypoglycemia without impacting potassium lowering. Journal of Hospital Medicine 2016;11:355-357. © 2016 Society of Hospital Medicine.

Safety of Eplerenone for Kidney-Transplant Recipients with Impaired Renal Function and Receiving Cyclosporine A

Background

Animal studies have highlighted the role of vascular mineralocorticoid receptor during Cyclosporine A-induced nephrotoxicity. Mineralocorticoid receptor antagonists could improve kidney survival but are not commonly used during renal impairment and in association with several immunosuppressive drugs due to a supposed higher risk of adverse events. We tested the tolerance of eplerenone according to its expected adverse events: hyperkalemia, metabolic acidosis, hypotension, acute kidney failure, or any other adverse event.

Methods

We conducted a single-center, prospective, open-label study in 31 kidney-transplant recipients with impaired renal function (30 and 50 mL/min/1.73m²) and receiving cyclosporine A. All patients received eplerenone 25 mg/d for 8 weeks. Serum potassium, renal function and expected adverse events were closely monitored.

Results

Eight patients experienced mild hyperkalemia (>5 mmol/L), one moderate hyperkalemia (>5.5 mmol/L) and had to receive potassium-exchange resin. No severe hyperkalemia (>6 mmol/L) occurred. One acute kidney failure was observed, secondary to diarrhea. Basal serum potassium and bicarbonate were independently associated with a higher risk of developing mild hyperkalemia (>5 mmol/L) under treatment (OR 6.5, p = 0.003 and 0.7, p = 0.007, respectively). A cut-off value of 4.35 mmol/L for basal serum potassium was the best factor to predict the risk of developing mild hyperkalemia (>5 mmol/L).

Conclusions

Until eGFR falls to 30 mL/min/1.73m², eplerenone could be safely given to kidney-transplant recipients receiving cyclosporine A, if kalemia is closely monitored. When renal function is impaired and if basal kalemia is >4.35 mmol/L, then clinicians should properly balance risk and benefit of eplerenone use and offer dietary advice. An adequately powered prospective randomized study is now needed to test its efficiency (and safety) in this population.

Trial Registration

ClinicalTrials.gov NCT01834768

The safety of mineralocorticoid receptor antagonists (MRAs) in patients with heart failure

INTRODUCTION

Mineralocorticoid receptor antagonists (MRAs) have been accorded a class 1 indication for patients with chronic heart failure and a reduced left ventricular ejection fraction (HFREF) in both European and American guidelines. Uptake, however, has been less than optimal largely due to concerns about their safety, in particular the risk of hyperkalemia and renal dysfunction.

AREAS COVERED

This review presents the current state of affairs regarding the safety of MRAs in heart failure with reduced ejection fraction.

EXPERT OPINION

Careful patient selection and adherence to guideline-recommended inclusion and exclusion criteria, dosing, and serial monitoring of serum potassium and renal function, along with patient education regarding the potassium content of common foods, should minimize these risks and allow increased use of MRAs. Additionally, this may also result in a further reduction in cardiovascular mortality and hospitalizations for heart failure. The development of new non-steroidal MRAs, and especially new potassium binding molecules that are well tolerated and effective, hold the promise for increased safety and, therefore, increased and more prolonged use of MRAs in patients with heart failure, especially those with chronic kidney disease, diabetes mellitus, and the elderly.

Potassium homeostasis and dyskalemias: the respective roles of renal, extrarenal, and gut sensors in potassium handling

Integrated mechanisms controlling the maintenance of potassium homeostasis are well established and are defined by the classic "feedback control" of potassium balance. Recently, increasing investigative attention has focused on novel physiological paradigms that increase the complexity and precision of homeostasis. This review briefly considers the classic and well-established feedback control of potassium and then considers subsequent investigations that inform on an intriguing and not widely recognized complementary paradigm: the "feed-forward control of potassium balance." Feed-forward control refers to a pathway in a homeostatic system that responds to a signal in the environment in a predetermined manner, without responding to how the system subsequently reacts (i.e., without responding to feedback). Studies in several animal species, and recently in humans, have confirmed the presence of a feed-forward control mechanism that is capable of mediating potassium excretion independent of changes in serum potassium concentration and aldosterone. Knowledge imparted by this update of potassium homeostasis hopefully will facilitate the clinical management of hyperkalemia in patients with chronic and recurrent hyperkalemia. Awareness of this updated integrative control mechanism for potassium homeostasis is more relevant today when the medical community is increasingly focused on leveraging and expanding established renin-angiotensin-aldosterone system inhibitor treatment regimens and on successfully coping with the challenges of managing hyperkalemia provoked by renin-angiotensin-aldosterone system inhibitors. These new insights are relevant to the future design of clinical trials delineating renal potassium handling.

Achieving the Benefits of a High-Potassium, Paleolithic Diet, Without the Toxicity

The average US dietary intake of K(+) is well below the current recommended nutritional requirements. This deficiency is even more striking when comparing our current intake with that of our ancestors, who consumed large amounts of dietary K(+). K(+) deficiency has been implicated in many diseases including cardiovascular disease, kidney stones, and osteoporosis. Importantly, dietary supplementation of K(+) has favorable effects on reducing blood pressure, decreasing the risk of stroke, improving bone health, and reducing the risk of nephrolithiasis. For this comprehensive review, we scanned the literature using PubMed and MEDLINE using the following search terms: potassium intake, renal potassium excretion, and prevention of hyperkalemia. Articles were selected for inclusion if they represented primary data or review articles published between 1980 and 2015 in high-impact journals. The normal kidney has the capacity to tightly regulate K(+) homoeostasis. We discuss new findings with respect to sensing mechanisms by which the kidney maintains K(+) homeostasis in the gastrointestinal tract and distal tubule. There are widely prescribed hypertensive medications that cause hyperkalemia and thus require dietary K(+) restriction. We conclude by discussing newly approved drugs capable of binding K(+) in the gastrointestinal tract and speculate that this new pharmacology might allow diet liberalization in patients at risk for hyperkalemia, affording them the numerous benefits of a K(+)-rich diet.

Patiromer

Each month, subscribers to The Formulary Monograph Service receive 5 to 6 well-documented monographs on drugs that are newly released or are in late phase 3 trials. The monographs are targeted to Pharmacy & Therapeutics Committees. Subscribers also receive monthly 1-page summary monographs on agents that are useful for agendas and pharmacy/nursing in-services. A comprehensive target drug utilization evaluation/medication use evaluation (DUE/MUE) is also provided each month. With a subscription, the monographs are sent in print and are also available on-line. Monographs can be customized to meet the needs of a facility. A drug class review is now published monthly with The Formulary Monograph Service. Through the cooperation of The Formulary, Hospital Pharmacy publishes selected reviews in this column. For more information about The Formulary Monograph Service, contact Wolters Kluwer customer service at 866-397-3433. The April 2016 monograph topics are von Willebrand factor (recombinant), daratumumab, elotuzumab, uridine triacetate, and ixazomib. The MUE is on lesinurad.

Has RAAS Blockade Reached Its Limits in the Treatment of Diabetic Nephropathy?

Medications that block the renin-angiotensin-aldosterone system (RAAS) are a cornerstone of diabetic nephropathy treatment. These agents play an important role in slowing the nephropathy progression in patients with diabetes. Clinical outcome trials that investigated use of these drug classes in patients with diabetic nephropathy have demonstrated clinical significant benefit in slowing nephropathy progression only in people with >300 mg/day of proteinuria. Thus, guidelines mandate their use in such patients. Conversely, combinations of RAAS blocking agents in these patients can worsen renal outcomes. Moreover, use of RAAS blockers in patients with a glomerular filtration rate below 45 mL/min/1.73 m(2) is limited by hyperkalemia. New agents that predictably bind excess potassium in the colon offer the possibility of extending RAAS inhibitor use in advanced chronic kidney disease (CKD) to allow evaluation of RAAS blockade for nephropathy and cardiovascular outcomes. These new potassium-binding agents may provide an opportunity to continue full-dose RAAS inhibition and assess if the benefits of RAAS blockade seen in stage 3 CKD can be extrapolated to persons with stages 4 and 5 CKD, not previously tested due to hyperkalemia.

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

OBJECTIVE

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

DATA SOURCES

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

STUDY SELECTION AND DATA EXTRACTION

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

DATA SYNTHESIS

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

CONCLUSIONS

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

Hyperkalemia constitutes a constraint for implementing renin-angiotensin-aldosterone inhibition: the widening gap between mandated treatment guidelines and the real-world clinical arena

Recent studies have reported a large gap between the forceful and assertive recommendations in the guidelines and real-world practice in the use of renin-angiotensin-aldosterone inhibitors (RAASi) therapies. A comprehensive, retrospective analysis of a large database of electronic medical records (>7 million patients) was undertaken to evaluate 3 pivotal concerns: (i) whether RAASi are being prescribed according to treatment guidelines, (ii) what happens to RAASi prescriptions after hyperkalemia events, and (iii) what the clinical outcomes are in patients whose RAASi are discontinued or who are prescribed at doses lower than the guidelines recommend. The results indicate that a substantial gap exists between guideline recommendations and real-world prescribing patterns for RAASi. Among patients with cardiorenal comorbidities for which RAASi are recommended by the guidelines, more than one-half were prescribed lower-than-recommended doses, and approximately 14% to 16% discontinued RAASi therapy. RAASi prescribing patterns may be altered by the development of hyperkalemia. Moderate-to-severe hyperkalemia events were followed by down-titration or discontinuation of RAASi therapy in nearly one-half of all patients on maximal dose and by discontinuation in nearly one-third of patients on submaximal dose. This analysis highlights the challenge behind RAASi prescribing decisions, balancing the risk of provoking hyperkalemia with the benefits to reducing cardiorenal morbidity and mortality. Patients who are known to derive the greatest benefit from these drugs (chronic kidney disease patients with concomitant diabetes mellitus or heart failure) are the same patients who are at highest risk of developing hyperkalemia. These observations constitute a "call to action" to develop newer treatment modalities to lower serum potassium and to achieve and sustain normokalemia long-term.

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.

Hyporeninemic hypoaldosteronism and diabetes mellitus: Pathophysiology assumptions, clinical aspects and implications for management

Patients with diabetes mellitus (DM) frequently develop electrolyte disorders, including hyperkalemia. The most important causal factor of chronic hyperkalemia in patients with diabetes is the syndrome of hyporeninemic hypoaldosteronism (HH), but other conditions may also contribute. Moreover, as hyperkalemia is related to the blockage of the renin-angiotensin-aldosterone system (RAAS) and HH is most common among patients with mild to moderate renal insufficiency due to diabetic nephropathy (DN), the proper evaluation and management of these patients is quite complex. Despite its obvious relationship with diabetic nephropathy, HH is also related to other microvascular complications, such as DN, particularly the autonomic type. To confirm the diagnosis, plasma aldosterone concentration and the levels of renin and cortisol are measured when the RAAS is activated. In addition, synthetic mineralocorticoid and/or diuretics are used for the treatment of this syndrome. However, few studies on the implications of HH in the treatment of patients with DM have been conducted in recent years, and therefore little, if any, progress has been made. This comprehensive review highlights the findings regarding the epidemiology, diagnosis, and management recommendations for HH in patients with DM to clarify the diagnosis of this clinical condition, which is often neglected, and to assist in the improvement of patient care.

Resin-Induced Colonic Pseudotumor: Rare Complication from Chronic Use of Potassium Binders in a Hemodialysis Patient

Potassium-binding resins are widely used in the treatment of hyperkalemia, mostly in the acute setting. Gastrointestinal adverse events, although reported, are not frequently seen due to its short course of use. This report describes a case involving an end-stage renal disease patient on hemodialysis who developed a colonic mass after being on sodium polystyrene sulfonate chronically for persistent hyperkalemia. Gastrointestinal symptoms developed late during the treatment rather than early as reported previously in the literature. This mass was mistaken for a carcinomatous lesion, which initiated an extensive work-up as well as hospitalization that nearly resulted in a subtotal colectomy.

Potential New Agents for the Management of Hyperkalemia

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

Patiromer: a clinical review

IMPORTANCE

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

OBJECTIVE

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

EVIDENCE REVIEW

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

FINDINGS

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

CONCLUSIONS AND RELEVANCE

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

Recent advances in treatment of heart failure

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

Reduction of cardiovascular risk in chronic kidney disease by mineralocorticoid receptor antagonism

Cardiovascular disease is the leading cause of death and morbidity in people with chronic kidney disease, but there are few evidence-based treatments for reducing cardiovascular events in these patients. The failure of novel drug candidates to delay progression to end-stage renal disease and limit or abrogate cardiovascular morbidity and mortality has led to increased interest in a mineralocorticoid receptor (MR) antagonist-based treatment model to reduce cardiovascular risk in patients with chronic kidney disease and end-stage renal disease. Aldosterone concentrations and MR signalling are associated with an enhanced risk of cardiovascular injury and the incidence of sudden death, and MR blockade decreases the risk of cardiovascular events and sudden death in patients with reduced glomerular filtration rate. Since evidence from clinical trials shows that treatment with MR antagonists confers a morbidity and mortality advantage for patients with cardiovascular disorders, similar benefits might also accrue in patients with chronic kidney disease. Large prospective trials are urgently needed to answer this question. In this Review, I argue that despite differences in the pathophysiology and clinical features of cardiovascular disease in patients with and without chronic kidney disease, MR antagonists could provide cardiovascular benefit in patients with chronic kidney disease.

Management of Hyperkalemia: An Update for the Internist

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

Randomized Clinical Trial of Sodium Polystyrene Sulfonate for the Treatment of Mild Hyperkalemia in CKD

BACKGROUND AND OBJECTIVES

Hyperkalemia affects up to 10% of patients with CKD. Sodium polystyrene sulfonate has long been prescribed for this condition, although evidence is lacking on its efficacy for the treatment of mild hyperkalemia over several days. This study aimed to evaluate the efficacy of sodium polystyrene sulfonate in the treatment of mild hyperkalemia.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In total, 33 outpatients with CKD and mild hyperkalemia (5.0-5.9 mEq/L) in a single teaching hospital were included in this double-blind randomized clinical trial. We randomly assigned these patients to receive either placebo or sodium polystyrene sulfonate of 30 g orally one time per day for 7 days. The primary outcome was the comparison between study groups of the mean difference of serum potassium levels between the day after the last dose of treatment and baseline.

RESULTS

The mean duration of treatment was 6.9 days. Sodium polystyrene sulfonate was superior to placebo in the reduction of serum potassium levels (mean difference between groups, -1.04 mEq/L; 95% confidence interval, -1.37 to -0.71). A higher proportion of patients in the sodium polystyrene sulfonate group attained normokalemia at the end of their treatment compared with those in the placebo group, but the difference did not reach statistical significance (73% versus 38%; P=0.07). There was a trend toward higher rates of electrolytic disturbances and an increase in gastrointestinal side effects in the group receiving sodium polystyrene sulfonate.

CONCLUSIONS

Sodium polystyrene sulfonate was superior to placebo in reducing serum potassium over 7 days in patients with mild hyperkalemia and CKD.

Pharmacological interventions for the acute management of hyperkalaemia in adults

BACKGROUND

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

OBJECTIVES

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

SEARCH METHODS

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

SELECTION CRITERIA

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

DATA COLLECTION AND ANALYSIS

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

MAIN RESULTS

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

AUTHORS' CONCLUSIONS

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

Potassium and Its Discontents: New Insight, New Treatments

Hyperkalemia is common in patients with impaired kidney function or who take drugs that inhibit the renin-angiotensin-aldosterone axis. During the past decade, substantial advances in understanding how the body controls potassium excretion have been made, which may lead to improved standard of care for these patients. Renal potassium disposition is primarily handled by a short segment of the nephron, comprising part of the distal convoluted tubule and the connecting tubule, and regulation results from the interplay between aldosterone and plasma potassium. When dietary potassium intake and plasma potassium are low, the electroneutral sodium chloride cotransporter is activated, leading to salt retention. This effect limits sodium delivery to potassium secretory segments, limiting potassium losses. In contrast, when dietary potassium intake is high, aldosterone is stimulated. Simultaneously, potassium inhibits the sodium chloride cotransporter. Because more sodium is then delivered to potassium secretory segments, primed by aldosterone, kaliuresis results. When these processes are disrupted, hyperkalemia results. Recently, new agents capable of removing potassium from the body and treating hyperkalemia have been tested in clinical trials. This development suggests that more effective and safer approaches to the prevention and treatment of hyperkalemia may be on the horizon.

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

AIMS

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

METHODS AND RESULTS

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

CONCLUSION

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

Cation Exchange Resins and colonic perforation. What surgeons need to know

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Cation Exchange Resins have been the mainstream treatment for chronic hyperkalemia.

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In 1987 the first case series of uremic patients with colonic perforations associated with the use of sodium polystyrene sulfonate was reported.

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The pathologic damage of Cation Exchange Resin in gastrointestinal tract goes from mucosal edema, ulcers, pseudomembranes, and the most severe transmural necrosis.

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Surgeons must avoid therapies with intestinal osmotic challenge implication in patients presenting gastrointestinal adverse reactions derived from Cation Exchange Resins.

Introduction

Since 1961 the use of Cation Exchange Resins has been the mainstream treatment for chronic hyperkalemia. For the past 25 years different kind of complications derived from its clinical use have been recognized, being the colonic necrosis the most feared and lethal of all.

Presentation of case

We report a case of a 72-year-old patient with chronic kidney disease, treated with calcium polystyrene sulfonate for hyperkalemia treatment who presented in the emergency department with constipation treated with hypertonic cathartics. With clinical deterioration 48 h later progressed with colonic necrosis requiring urgent laparotomy, sigmoidectomy and open abdomen management with subsequent rectal stump perforation and dead. The histopathology finding: calcium polystyrene sulfonate embedded in the mucosa, consistent with the cause of perforation.

Discussion

Lillemoe reported the first case series of five uremic patients with colonic perforation associated with the use of SPS in sorbitol in 1987 and in 2009 the FDA removed from the market the SPS containing 70% of sorbitol.

The pathophysiologic change of CER goes from mucosal edema, ulcers, pseudomembranes, and the most severe case transmural necrosis.

Up to present day, some authors have questioned the use of CER in the setting of lowering serum potassium. Despite its worldwide use in hyperkalemia settings, multiple studies have not demonstrated a significant potassium excretion by CER.

Conclusion

Despite the low incidence of colonic complication and lethal colonic necrosis associated with the CER clinical use, the general surgeon needs a high index of suspicion when dealing with patients treated with CER and abdominal pain.

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

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

An update of the blockade of the renin angiotensin aldosterone system in clinical practice

INTRODUCTION

Cardiovascular disease (CVD) is the leading cause of death worldwide. Blockade of this system is commonly used in the treatment of cardiovascular (CV) and renal disease.

AREAS COVERED

Data from multiple clinical trials have provided good evidence about the benefit of blocking the system as a therapeutic target to reduce CV and renal events. We have reviewed all the tested combinations of different drugs counteracting the effects of the renin-angiotensin-aldosterone system.

EXPERT OPINION

Monotherapy with an angiotensin-converting enzyme inhibitor (ACEi) or an angiotensin II receptor blocker (ARB) remains valid in all the guidelines, whereas their dual combination has been discarded due to the absence of proven benefits in high CV risk patients and in patients with chronic kidney disease (CKD). The combination of the standard therapy with an ACEi or an ARB with a mineralocorticoid receptor blocker is a valid option, but has the inconvenience of frequent hyperkalemia in patients with CKD. Similarly, the addition of the direct renin inhibitor, aliskiren, to this standard therapy is not particularly supported in diabetic patients. New dual-acting blockers, for example, those combining valsartan and neprilysin inhibitors (LCZ696-Novartis) or endothelin converting enzyme inhibitors and neprilysin inhibitors (ECEI, Daglutril-Solvay), are currently under investigation.

Advances in treatment of hyperkalemia in chronic kidney disease

INTRODUCTION

Hyperkalemia is a frequent electrolyte disorder associated with life-threatening cardiac arrhythmias and sudden death. Patients prone to hyperkalemia have chronic kidney disease (CKD) either alone or in conjunction with diabetes or heart failure (HF). Although agents inhibiting the renin-angiotensin-aldosterone-system (RAAS) are currently the first-line treatments toward cardio- and nephroprotection, their administration often leads to potassium elevation in such patients and results in high rates of treatment discontinuation.

AREAS COVERED

This article provides an overview of factors interfering with potassium homeostasis and discusses emerging potassium-lowering therapies for long-term management of hyperkalemia.

EXPERT OPINION

In recent randomized clinical studies, two new oral potassium-exchanging compounds, patiromer and sodium zirconium cyclosilicate, were shown to effectively normalize elevated serum potassium and chronically maintain potassium homeostasis in hyperkalemic patients treated with RAAS blockers. Both agents exhibit good tolerability and were not associated with serious adverse effects. Although additional research is required, these drugs are promising for lowering the risk of incident hyperkalemia associated with RAAS blockade use in people with diabetes or HF who have CKD. They also provide the opportunity to test whether patients who could not previously receive RAAS blockade may benefit from their cardio- and renoprotective effects.

Combination use of medicines from two classes of renin-angiotensin system blocking agents: risk of hyperkalemia, hypotension, and impaired renal function

European and United States regulatory agencies recently issued warnings against the use of dual renin-angiotensin system (RAS) blockade therapy through the combined use of angiotensin-converting enzyme inhibitors (ACEIs), angiotensin II receptor blockers (ARBs) or aliskiren in any patient, based on absence of benefit for most patients and increased risk of hyperkalemia, hypotension, and renal failure. Special emphasis was made not to use these combinations in patients with diabetic nephropathy. The door was left open to therapy individualization, especially for patients with heart failure, when the combined use of an ARB and ACEI is considered absolutely essential, although renal function, electrolytes and blood pressure should be closely monitored. Mineralocorticoid receptor antagonists were not affected by this warning despite increased risk of hyperkalemia. We now critically review the risks associated with dual RAS blockade and answer the following questions: What safety issues are associated with dual RAS blockade? Can the safety record of dual RAS blockade be improved? Is it worth trying to improve the safety record of dual RAS blockade based on the potential benefits of the combination? Is dual RAS blockade dead? What is the role of mineralocorticoid antagonists in combination with other RAS blocking agents: RAAS blockade?

Optimizing haemodialysate composition

Survival and quality of life of dialysis patients are strictly dependent on the quality of the haemodialysis (HD) treatment. In this respect, dialysate composition, including water purity, plays a crucial role. A major aim of HD is to normalize predialysis plasma electrolyte and mineral concentrations, while minimizing wide swings in the patient's intradialytic plasma concentrations. Adequate sodium (Na) and water removal is critical for preventing intra- and interdialytic hypotension and pulmonary edema. Avoiding both hyper- and hypokalaemia prevents life-threatening cardiac arrhythmias. Optimal calcium (Ca) and magnesium (Mg) dialysate concentrations may protect the cardiovascular system and the bones, preventing extraskeletal calcifications, severe secondary hyperparathyroidism and adynamic bone disease. Adequate bicarbonate concentration [HCO₃⁻] maintains a stable pH in the body fluids for appropriate protein and membrane functioning and also protects the bones. An adequate dialysate glucose concentration prevents severe hyperglycaemia and life-threating hypoglycaemia, which can lead to severe cardiovascular complications and a worsening of diabetic comorbidities.

Hypertension Management in Diabetic Kidney Disease

IN BRIEF Hypertension is prevalent in most individuals with diabetic kidney disease (DKD). Failure to treat hypertension appropriately in this subgroup of patients results in an increased risk of cardiovascular morbidity and mortality, as well as a faster progression of kidney disease. The current guidance for appropriate treatment of hypertension in this high-risk population provides an opportunity to improve both kidney and cardiovascular outcomes. This review discusses the current state of evidence-based hypertension management in patients with DKD.