The tolerability and safety profile of patiromer: a novel polymer-based potassium binder for the treatment of hyperkalemia

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.

Efficacy and safety of potassium binders in the treatment of patients with chronic kidney disease and hyperkalemia

BACKGROUND

Gastrointestinal cation exchangers that can bind potassium in the gut, including sodium polystyrene sulfonate (SPS), calcium polystyrene sulfonate (CPS), patiromer and sodium zirconium cyclosilicate (SZC), are emerging medications for the treatment of hyperkalemia with chronic kidney disease (CKD). However, which might be the best alternative for patients with chronic kidney disease and hyperkalemia remains disputed.

METHODS

We performed this systematic review and network meta-analysis with the Bayesian approach to conduct direct and indirect comparisons among potassium binders regarding their efficacy and safety. The surface under the cumulative ranking curve analysis (SUCRA) was used to calculate the best intervention for each outcome.

RESULTS

All four potassium binders had a promising effect regarding potassium reduction. SPS had favorable efficacy and safety for short-term use (MD: -0.94; 95% CIs: -1.4 to -0.48; SUCRA = 94.69%), but long-term treatment required strict dose control and assessment of gastrointestinal conditions. CPS had a positive effect on reducing potassium, and could especially maintain the serum potassium concentration in patients receiving renin-angiotensin-aldosterone system inhibitors (RAASi). Patiromer might reduce all-cause mortality in CKD patients with hyperkalemia and have a positive effect on potassium-lowering, though it had significant gastrointestinal adverse effects. SZC had a potassium-lowering effect in both the short-term and long-term, and can be a promising long-term treatment for the hyperkalemia in CKD patients, especially in combination with RAASi.

CONCLUSION

These four potassium binders had their own advantages and disadvantages, and the medication should be selected according to the clinical situation of the patient.

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

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

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

AIMS

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

METHODS AND RESULTS

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

CONCLUSIONS

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

Mineralocorticoid Receptor Antagonists-Use in Chronic Kidney Disease

Mineralocorticoid receptor antagonists (MRA) are drugs with a potentially broad spectrum of action. They have been reported to have healing effects in many diseases, such as chronic heart failure, hypertension, or nephrotic syndrome. Numerous studies suggest that mineralocorticoid receptor activation is pathogenic and a progression factor of chronic kidney disease (CKD); however, results of studies on the use of MRA in the treatment of CKD are inconclusive. Current guidelines recommend against the use of MRA in patients with advanced CKD. Although, there is growing interest on their use in this population due to treatment benefits. In this review, we summarize studies which were purposed to evaluate the impact of MRA therapy on CKD patients. Despite many benefits of this treatment e.g., reducing cardiovascular mortality or alleviating proteinuria, steroidal MRA (such as spironolactone or eplerenone) have a low safety profile. They often lead to hyperkalemia complications which are dangerous in patients with CKD, and diabetic nephropathy, especially in hemodialysis patients. Studies on recently developed nonsteroidal MRA showed that they have fewer side effects. In our review, we discuss steroidal and nonsteroidal MRA treatment effects on the estimated glomerular filtration rate (eGFR), proteinuria, the cardiovascular system, and hyperkalemia in CKD patients. We present new content and recent publications in this field.

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

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

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).

New Treatment Options for Hyperkalemia in Patients with Chronic Kidney Disease

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

Evolution of Patiromer Use: a Review

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

Potassium Binders for Hyperkalemia in Chronic Kidney Disease-Diet, Renin-Angiotensin-Aldosterone System Inhibitor Therapy, and Hemodialysis

Hyperkalemia is a potentially life-threatening complication of chronic kidney disease (CKD). The management of CKD requires balancing the benefits of specific treatments, which may exacerbate the potential for hyperkalemia, with the risks of hyperkalemia itself. Renin-angiotensin-aldosterone system (RAAS) inhibitors, which slow CKD progression and improve cardiovascular outcomes, are often discontinued if hyperkalemia develops. Patients with hyperkalemia are frequently advised to restrict dietary potassium (K⁺), depriving these patients of many heart-healthy foods. Patients receiving hemodialysis are particularly susceptible to hyperkalemia during long interdialytic intervals, and managing this risk without causing hypokalemia can be challenging. Recently, 2 K⁺-binding agents were approved for the treatment of hyperkalemia: sodium zirconium cyclosilicate and patiromer. These agents offer alternatives to sodium polystyrene sulfonate, which is associated with serious gastrointestinal adverse effects. For this review, PubMed was searched for English-language articles published in 2014-2018 using the terms patiromer, sodium zirconium cyclosilicate, sodium polystyrene sulfonate, hyperkalemia, renin-angiotensin-aldosterone, diet, and dialysis. In randomized controlled studies of patients with hyperkalemia, sodium zirconium cyclosilicate and patiromer effectively reduced serum K⁺ and were generally well tolerated. Furthermore, patients in these studies could maintain RAAS inhibitor therapy and, in some studies, were not required to limit dietary K⁺. There may also be a role for these agents in preventing hyperkalemia in patients receiving hemodialysis. Thus, K⁺-binding agents may allow patients with CKD at risk for hyperkalemia to optimize RAAS inhibitor therapy, receive benefits of a K⁺-rich diet, and experience improved hemodialysis outcomes. Additional long-term studies are necessary to confirm these effects.

New therapies for hyperkalemia

PURPOSE OF REVIEW

Although renin-angiotensin aldosterone system (RAAS) inhibitors have become the mainstay treatment for patients with chronic diseases, hyperkalemia is a major contributory deterrent to their use in patients with chronic kidney disease (CKD) and heart failure. For the first time in 50 years, two new therapies (patiromer and ZS-9) have recently emerged for the concomitant treatment of hyperkalemia in these patients. The objective of this review is to discuss the efficacy and safety of these new agents.

RECENT FINDINGS

Patiromer effectively reduces serum potassium in patients with CKD and heart failure, even with the concomitant use of RAAS inhibitors. The most common adverse events in clinical trials were gastrointestinal events. ZS-9 (Lokelma) rapidly reduces serum potassium levels and to a greater magnitude, and has a role in the acute management of hyperkalemia. Despite having more adverse events than patiromer, ZS-9 is overall well tolerated.

SUMMARY

These new therapies show promising results for the chronic management of hyperkalemia, whilst also potentially allowing for the concomitant use of RAAS inhibitors at optimal doses. More research is needed to examine the benefits of continuation of RAAS inhibitors after an episode of hyperkalemia in patients with CKD and heart failure.

Pharmacology of new treatments for hyperkalaemia: patiromer and sodium zirconium cyclosilicate

Hyperkalaemia is a life-threatening condition, resulting from decreased renal function or dysfunctional homoeostatic mechanisms, often affecting patients with cardiovascular (CV) disease. Drugs such as renin-angiotensin-aldosterone system inhibitors (RAASi) are known to improve outcomes in CV patients but can also cause drug-induced hyperkalaemia. New therapeutic options exist to enhance potassium excretion in these patients. To this aim, we reviewed pharmacological properties and available data on patiromer and sodium zirconium cyclosilicate for the treatment of hyperkalaemia. These agents have been shown in randomized trials to significantly reduce serum potassium in patients with hyperkalaemia on renin-angiotensin-aldosterone system inhibitors. Additional research should focus on their long-term effects/safety profiles and drug-drug interactions.

Patiromer: A Review in Hyperkalaemia

Patiromer (Veltassa^®) for oral suspension is a non-absorbed, sodium-free potassium binding polymer that exchanges calcium for potassium in the gastrointestinal (GI) tract, thereby increasing faecal potassium excretion and reducing serum potassium levels. Patiromer was approved in the USA in 2015 and is now approved in several other countries, including those of the EU, for the treatment of hyperkalaemia in adults. In clinical trials, patiromer reduced serum potassium levels and the risk of recurrent hyperkalaemia in patients with chronic kidney disease (CKD) and/or diabetic nephropathy with or without heart failure (HF), allowing the majority of patients to continue receiving renin-angiotensin-aldosterone system (RAAS) inhibitors (drugs that inhibit the renal excretion of potassium) for up to 52 weeks. Patiromer also maintained normokalaemia in patients with HF and a propensity for hyperkalaemia, enabling concomitant administration and up-titration of spironolactone. Patiromer was generally well tolerated, with a low risk of hypokalaemia. GI disorders and hypomagnesaemia were the most common adverse events; these were generally of mild or moderate severity. Therefore, oral patiromer is a valuable treatment option for the long-term management of hyperkalaemia.