Safety and efficacy of patiromer use with tacrolimus in kidney transplant recipients

Patiromer Does Not Alter Tacrolimus Pharmacokinetics in Kidney Transplant Recipients When Administered Three Hours Post-Tacrolimus

Background

Hyperkalemia is common in kidney transplant (KTx) recipients. Patiromer, a potassium-binding polymer used to treat acute and chronic hyperkalemia, has the potential to bind charged particles in the gastrointestinal tract and thereby potentially affect the absorption of coadministered drugs. The immunosuppressive drug tacrolimus (Tac) has a narrow therapeutic window, is susceptible to drug-drug interactions (DDIs), and a potential gastrointestinal interaction with patiromer could elevate the risk of allograft rejection. We aimed to investigate the potential DDI between patiromer and Tac pharmacokinetics in KTx with hyperkalemia by sampling capillary blood using volumetric absorptive microsampling (VAMS).

Methods

Thirteen KTx recipients on Tac twice daily (BID) with plasma potassium levels of >4.6 mmol/L were included. Two 12 h Tac pharmacokinetic investigations were performed with and without 8.4 mg patiromer/d for 1 wk. Oral Tac dose remained unchanged and patiromer was administered 3 h after Tac dose. Tac sampling was self-conducted using VAMS after mastering the technique.

Results

Ten patients provided 2 evaluable pharmacokinetic profiles. The Tac area under the curve (AUC)0-12 ratio (AUCTac+patiromer/AUCTac) was 0.99 (90% confidence interval [CI], 0.86-1.14), and the Cmax ratio was 1.01 (90% CI, 0.86-1.19). Tac C0 and C12 fulfilled the bioequivalence criteria with a ratio of 0.98 (90% CI, 0.90-1.07) and 0.93 (90% CI, 0.83-1.04), respectively.

Conclusions

When administered 3 h after the Tac morning dose, patiromer has no clinically relevant impact on Tac pharmacokinetics. We demonstrate that VAMS is a well-suited sampling method to simplify the execution of DDI studies.

Novel Potassium Binders for Early Postoperative Hyperkalemia in Kidney Transplant Recipients: A Single-Center Experience

PURPOSE

Evaluate the safety/efficacy of novel potassium binders (patiromer, sodium zirconium cyclosilicate [SZ-9]) for early postoperative hyperkalemia following kidney transplantation.

METHODS

Retrospective, single-center, cohort study of deceased-donor kidney recipients transplanted between 1/2018 and 12/2020. Potassium-binder use was evaluated from immediately posttransplant until discharge. Potassium binders were administered ≥2 hours before/after medications.

RESULTS

A total of 179 patients were included, 24 (13%) of whom received potassium binders (16 [67%] patiromer, 7 [29%] SZ-9, 1 [4%] both) for a mean of 2.5 (±3.18) doses. Peak potassium levels were higher in the potassium-binder group (6.05 vs 5.35 mEq/L; P < .001). More patients on potassium binders transitioned to atovaquone than those on no binders (n = 21 [100%] vs n = 112 [75%], respectively; P = .005). Delayed graft function (DGF) was observed in 100 (56%) patients, with a higher proportion receiving potassium binders (18 [75%] vs 82 [53%], respectively; P = .042). There was no difference between groups in number of posttransplant dialysis sessions required in the general study population (P = .2), nor in the DGF group (P = .12). No difference was noted in the incidence of ileus (P = .2), or gastrointestinal symptoms (diarrhea, nausea, vomiting; P = .6). Of the 24 patients who received inpatient binders, 9 (37.5%) were discharged and remained on them for a mean of 46 (±49) days.

CONCLUSION

Patiromer and SZ-9 appear safe in the early posttransplant period, but larger prospective trials are needed. Potassium-binder use does not appear to be associated with fewer dialysis sessions in DGF patients, however, they may be used as additional tools for lowering potassium in these patients.

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.

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).

Management of hyperkalemia: A focus on kidney transplant recipients

Hyperkalemia is a frequent complication among kidney transplant recipients that can lead to fatal arrhythmias. The causes of hyperkalemia post kidney transplant are multifactorial and often are drug-induced, and include decreased glomerular filtration rate, tubular dysfunction, and impaired sodium delivery in the distal nephron. This review will discuss pathophysiology and recent updates in the management of both acute and chronic hyperkalemia with a focus on kidney transplant recipients.

Novel approaches to management of hyperkalaemia in kidney transplantation

PURPOSE OF REVIEW

Medications used frequently after kidney transplantation, including calcineurin inhibitors, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, beta blockers and antimicrobials, are considered the leading culprit for posttransplant hyperkalaemia in recipients with a well functioning allograft. Other risk factors include comorbidities such as diabetes, hypertension and heart failure; and consumption of a potassium-enriched diet. We review the mechanisms for hyperkalaemia following kidney transplantation that are addressed using nonpharmacological and pharmacological interventions. We also discuss emerging therapeutic approaches for the management of recurrent hyperkalaemia in solid organ transplantation, including newer potassium binding therapies.

RECENT FINDINGS

Patiromer and sodium zirconium cyclosilicate are emerging potassium binders approved for the treatment of hyperkalaemia. Patiromer is a polymer that exchanges potassium for calcium ions. In contrast, sodium zirconium cyclosilicate is a nonpolymer compound that exchanges potassium for sodium and hydrogen ions. Both agents are efficacious in the treatment of chronic or recurrent hyperkalaemia and may result in fewer gastrointestinal side effects than older potassium binders such as sodium polystyrene sulfonate and calcium polystyrene sulfonate. Large-scale clinical studies have not been performed in kidney transplant patients. Patiromer may increase serum concentrations of tacrolimus, but not cyclosporine. Sodium zirconium cyclosilicate does not appear to compromise tacrolimus pharmacokinetics, although it may have a higher sodium burden.

SUMMARY

Patiromer and sodium zirconium cyclosilicate may be well tolerated options to treat asymptomatic hyperkalaemia and have the potential to ease potassium dietary restrictions in kidney transplant patients by maintaining a plant-dominant, heart-healthy diet. Their efficacy, better tolerability and comparable cost with respect to previously available potassium binders make them an attractive therapeutic option in chronic hyperkalaemia following kidney transplantation.

Pre-Transplant Plasma Potassium as a Potential Risk Factor for the Need of Early Hyperkalaemia Treatment after Kidney Transplantation: A Cohort Study

INTRODUCTION

Plasma potassium (K+) abnormalities are common among patients with chronic kidney disease and are associated with higher rates of death, major adverse cardiac events, and hospitalization in this population. Currently, no guidelines exist on how to handle pre-transplant plasma K+ in renal transplant recipients (RTR).

OBJECTIVE

The aim of this study is to examine the relation between pre-transplant plasma K+ and interventions to resolve hyperkalaemia within 48 h after kidney transplantation.

METHODS

In a single-centre cohort study, we addressed the association between the last available plasma K+ level before transplantation and the post-transplant need for dialysis or use of K+-lowering medication to resolve hyperkalaemia within 48 h after renal transplantation using multivariate logistic regression analysis.

RESULTS

151 RTR were included, of whom 51 (33.8%) patients received one or more K+ interventions within 48 h after transplantation. Multivariate regression analysis revealed that a higher pre-transplant plasma K+ was associated with an increased risk of post-transplant intervention (odds ratio 2.2 [95% CI: 1.1-4.4]), independent of donor type (deceased or living) and use of K+-lowering medication within 24 h prior to transplantation).

CONCLUSIONS

This study indicates that a higher pre-transplant plasma K+ is associated with a higher risk of interventions necessary to resolve hyperkalaemia within 48 h after renal transplantation. Further research is recommended to determine a cutoff level for pre-transplant plasma K+ that can be used in practice.

Largest Experience of Safety and Efficacy of Patiromer in Solid Organ Transplant

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Tacrolimus ameliorates tubulointerstitial inflammation in diabetic nephropathy via inhibiting the NFATc1/TRPC6 pathway

Tubulointerstitial inflammation is crucial for the progression of diabetic nephropathy (DN), and tubular cells act as a driving force in the inflammatory cascade. Emerging data suggested that tacrolimus (TAC) ameliorates podocyte injury and macrophage infiltration in streptozotocin (STZ) mice. However, the effect of TAC on tubulointerstitial inflammation remains unknown. We found that albuminuria and tubulointerstitial damage improved in db/db mice treated with TAC. Macrophage infiltration and expression of IL‐6, TNF‐α, fibronectin, collagen 1 and cleaved caspase 3 were inhibited as well. In addition, the expression of nuclear factor of activated T cell 1 (NFATc1) and transient receptor potential channel 6 (TRPC6) was up‐regulated in the kidneys of DN patients and correlated with tubular injury and inflammation. The expression of NFATc1 and TRPC6 also increased in the kidneys of db/db mice and HK‐2 cells with high glucose (HG), while TAC inhibited these effects. HG‐induced inflammatory markers and apoptosis were reversed by TAC and NFATc1 siRNA in HK‐2 cells, which was abolished by TRPC6 plasmid. Furthermore, HG‐induced TRPC6 expression was inhibited by NFATc1 siRNA, while NFATc1 nuclear translocation was inhibited by TAC, but was restored by TRPC6 plasmid in HK‐2 cells under HG conditions. These findings suggest that TAC ameliorates tubulointerstitial inflammation in DN through NFATc1/TRPC6 feedback loop.

Cardiovascular disease in the kidney transplant recipient: epidemiology, diagnosis and management strategies

Kidney transplantation (KT) is the optimal therapy for end-stage kidney disease (ESKD), resulting in significant improvement in survival as well as quality of life when compared with maintenance dialysis. The burden of cardiovascular disease (CVD) in ESKD is reduced after KT; however, it still remains the leading cause of premature patient and allograft loss, as well as a source of significant morbidity and healthcare costs. All major phenotypes of CVD including coronary artery disease, heart failure, valvular heart disease, arrhythmias and pulmonary hypertension are represented in the KT recipient population. Pre-existing risk factors for CVD in the KT recipient are amplified by superimposed cardio-metabolic derangements after transplantation such as the metabolic effects of immunosuppressive regimens, obesity, posttransplant diabetes, hypertension, dyslipidemia and allograft dysfunction. This review summarizes the major risk factors for CVD in KT recipients and describes the individual phenotypes of overt CVD in this population. It highlights gaps in the existing literature to emphasize the need for future studies in those areas and optimize cardiovascular outcomes after KT. Finally, it outlines the need for a joint 'cardio-nephrology' clinical care model to ensure continuity, multidisciplinary collaboration and implementation of best clinical practices toward reducing CVD after KT.