Phosphate binding therapy in dialysis patients: focus on lanthanum carbonate

Past, Present, and Future of Phosphate Management

Cardiovascular (CV) disease (CVD) accounts for >50% of deaths with known causes in patients on dialysis. Elevated serum phosphorus levels are an important nontraditional risk factor for bone mineral disease and CVD in patients with chronic kidney disease (CKD). Given that phosphorus concentrations drive other disorders associated with increased CV risk (e.g., endothelial dysfunction, vascular calcification, fibroblast growth factor-23, parathyroid hormone), phosphate is a logical target to improve CV health. Phosphate binders are the only pharmacologic treatment approved for hyperphosphatemia. Although their safety has improved since inception, the mechanism of action leads to characteristics that make ingestion difficult and unpleasant; large pill size, objectionable taste, and multiple pills required for each meal and snack make phosphate binders a burden. Side effects, especially those affecting the gastrointestinal (GI) system, are common with binders, often leading to treatment discontinuation. The presence of “hidden” phosphates in processed foods and certain medications makes phosphate management even more challenging. Owing to these significant issues, most patients on dialysis are not consistently achieving and maintaining target phosphorus concentrations of <5.5 mg/dl, let alone more normal levels of <4.5 mg/dl, indicating novel approaches to improve phosphate management and CV health are needed. Several new nonbinder therapies that target intestinal phosphate absorption pathways have been developed. These include EOS789, which acts on the transcellular pathway, and tenapanor, which targets the dominant paracellular pathway. As observational evidence has established a strong association between phosphorus concentration and clinical outcomes, such as mortality, phosphate is an important target for improving the health of patients with CKD and end-stage kidney disease (ESKD).

NaLa(CO3)2 hybridized with Fe3O4 for efficient phosphate removal: Synthesis and adsorption mechanistic study

Effectively eutrophication control and phosphate recovery have received increasing attention in recent years. In this study, a regenerable magnetic NaLa(CO₃)₂/Fe₃O₄ composites (MLC) which includes a novel phosphate-binding lanthanum species NaLa(CO₃)₂ hybridized with Fe₃O₄ nanoparticle was developed through a modified solvothermal method for phosphate removal from contaminated water. Based upon preliminary screening of synthesized MLC with different La-to-Fe molar ratios in terms of phosphate adsorption capacity and synthetic product yield, a MLC composite with a La-to-Fe molar ratio of 2:1 (MLC-21) was selected for further characterization and evaluation. MLC-21 exhibits a high magnetic separation efficiency of 97%, high phosphate adsorption capacity of 77.85 mg P/g, wide applicable scope of pH ranging from 4 to 11, excellent selectivity for phosphate in the presence of competing ions (Cl^-, NO₃^-, HCO₃^-, SO₄^2-, Ca²⁺, and Mg²⁺), good reusability with above 98% desorption efficiency using NaOHNaCl mixture and 83% adsorption capacity remained during five recycles. Furthermore, a real effluent wastewater with phosphate concentration of 1.96 mg P/L was used to verify the performance of MLC-21 through a magnetic separation integrated system (AMSS). By using the response surface methodology (RSM), the optimum parameters were determined to be 0.26 g/L of adsorbent dosage, 26.28 h of adsorption time and 24.12 min of magnetic separation time for meeting the phosphate emission standard of 0.5 mg P/L. The phosphorus in three representative eutrophic water bodies can be efficiently reduced to below 0.1 mg P/L by MLC-21 adsorption at different dosages. Electrostatic attraction and the inner-sphere complexation between La(HCO₃)₂⁺/La(CO₃)₂^- and P via ligand exchange forming LaPO₄ were responsible for the phosphate adsorption mechanisms of MLC.

Synthesis of Mg-Fe-Cl hydrotalcite-like nanoplatelets as an oral phosphate binder: evaluations of phosphorus intercalation activity and cellular cytotoxicity

The patients with end-stage of renal disease (ESRD) need to take oral phosphate binder. Traditional phosphate binders may leave the disadvantage of aluminum intoxication or cardiac calcification. Herein, Mg-Fe-Cl hydrotalcite-like nanoplatelet (HTln) is for the first time characterized as potential oral phosphate binder, with respect to its phosphorus uptake capacity in cow milk and cellular cytotoxicity. A novel method was developed for synthesizing the Mg-Fe-Cl HTln powder in different Mg²⁺: Fe³⁺ ratios where the optimization was 2.8:1. Addition of 0.5 g Mg-Fe-Cl HTln in cow milk could reduce its phosphorus content by 40% in 30 min and by 65% in 90 min. In low pH environment, the Mg-Fe-Cl HTln could exhibit relatively high performance for uptaking phosphorus. During a 90 min reaction of the HTln in milk, no phosphorus restoration occurred. In-vitro cytotoxicity assay of Mg-Fe-Cl HTln revealed no potential cellular cytotoxicity. The cells that were cultured in the HTln extract-containing media were even more viable than cells that were cultured in extract-free media (blank control). The Mg-Fe-Cl HTln extract led to hundred ppm of Mg ion and some ppm of Fe ion in the media, should be a positive effect on the good cell viability.

Nonadherence to Medication Therapy in Haemodialysis Patients: A Systematic Review

Background

End-stage kidney disease (ESKD) patients are often prescribed multiple medications. Together with a demanding weekly schedule of dialysis sessions, increased number of medicines and associated regimen complexity pre-dispose them at high risk of medication nonadherence. This review summarizes existing literature on nonadherence and identifies factors associated with nonadherence to medication therapy in patients undergoing haemodialysis.

Methods

A comprehensive search of PubMed, Embase, CINAHL, PsycInfo, and Cochrane Database of Systematic Reviews covering the period from 1970 through November 2014 was performed following a predefined inclusion and exclusion criteria. Reference lists from relevant materials were reviewed. Data on study characteristics, measures of nonadherence, prevalence rates and factors associated with nonadherence were collected. The Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines was followed in conducting this systematic review.

Results

Of 920 relevant publications, 44 were included. The prevalence of medication nonadherence varied from 12.5% to 98.6%, with widespread heterogeneity in measures and definitions employed. Most common patient-related factors significantly associated with nonadherence were younger age, non-Caucasian ethnicity, illness interfering family life, being a smoker, and living single and being divorced or widowed. Similarly, disease-related factors include longevity of haemodialysis, recurrent hospitalization, depressive symptoms and having concomitant illness like diabetes and hypertension. Medication-related factors such as daily tablet count, total pill burden, number of phosphate binders prescribed and complexity of medication regimen were also associated with poor adherence.

Conclusions

A number of patient-, disease-, and medication-related factors are associated with medication nonadherence in haemodialysis patients. Clinicians should be aware of such factors so that adherence to medications can be optimised in haemodialysis patients. Future research should be directed towards well-designed prospective longitudinal studies developing standard definitions and validating available measurement tools, while focusing on the role of additional factors such as psychosocial and behavioural factors in predicting nonadherence to medications.

Ferric Citrate, an Iron-Based Phosphate Binder, Reduces Health Care Costs in Patients on Dialysis Based on Randomized Clinical Trial Data

BACKGROUND

Patients with end-stage renal disease (ESRD) require phosphate binders for hyperphosphatemia and erythropoiesis-stimulating agents (ESAs) and intravenous (i.v.) iron for anemia. Ferric citrate (FC) is a novel, iron-based phosphate binder that increases iron stores and decreases i.v. iron and ESA usage while maintaining hemoglobin levels, and may decrease the cost of ESRD care. The study objectives were to (1) quantify differences in ESA and i.v. iron usage among ESRD patients receiving FC compared with active control (AC) (sevelamer carbonate and/or calcium acetate) on the basis of data from a 52-week phase III clinical trial and (2) standardize trial data to the general United States (US) ESRD population and calculate the potential impact of FC on ESRD cost/patient/year in the USA.

STUDY DESIGN

The study was a randomized, controlled clinical trial.

SETTING AND POPULATION

A total of 441 adult subjects with ESRD who received FC or AC for 52 weeks were included.

MODEL, PERSPECTIVE, AND TIMELINE

Differences in ESA and i.v. iron usage between the treatment groups were modeled over time using generalized linear mixed models and zero-inflated Poisson models. Trends were modeled via logarithmic curves, and utilization patterns were applied to the general dialysis population to estimate expected resource savings.

OUTCOMES

Study outcomes were costs saved/patient/year using FC versus AC (US dollars).

RESULTS

Our model suggests an annual decrease of 129,106 U of ESAs and 1960 mg of i.v. iron per patient in the second year after a switch from AC to FC. Applying 2013 Medicare pricing, this would save $1585 in ESAs and $516 in i.v. iron: a total of $2101/patient/year; these savings would be expected to double for managed care plans.

LIMITATIONS

The projections were made on 1 year of trial data.

CONCLUSIONS

Phosphate binding with FC reduces i.v. iron and ESA usage. Given the high cost burden of ESRD, our model demonstrates significant potential cost savings.

TRIAL REGISTRATION

ClinicalTrials.gov (NCT01191255) http://clinicaltrials.gov/ct2/show/NCT01191255 .

Clinical and economic aspects of sevelamer therapy in end-stage renal disease patients

Phosphate control is still a great challenge in chronic kidney disease (CKD), and in spite of the great improvements in dialysis techniques, achievement of the goals for mineral metabolism control is still far from ideal. Aluminum hydroxide has been largely abandoned due to the high risk of aluminum toxicity, while the use of calcium-based phosphate binders may cause hypercalcemia, overzealous parathyroid suppression, and extraskeletal calcification. Sevelamer hydrochloride has been introduced as an efficient medication for phosphate control, with a lower risk of hypercalcemia and parathyroid suppression. Various clinical trials have compared the risk of vascular calcification between sevelamer and calcium salts with inconsistent results. In spite of these inconsistencies, the Kidney Disease Outcomes Quality Initiative (KDOQI) suggests non-calcium phosphate binders as the preferred phosphate binder in dialysis patients with severe vascular and/or other soft-tissue calcifications and in those with hypercalcemia or parathyroid hormone (PTH) <150 mg/dL. The Kidney Disease Improving Global Outcome (KDIGO) limits the use of non-calcium phosphate binders to patients with hypercalcemia. Regarding the effect on mortality, the results of clinical trials are again inconsistent. The other important aspect of using sevelamer is the issue of price, which is substantially higher than calcium-based phosphate binders. Reviewing the studies on economic aspects shows that sevelamer increases quality-adjusted life-years (QALY) and possibly life years, with a higher cost compared to calcium-based phosphate binders. In conclusion, sevelamer is a very useful drug for phosphate control, reduction of hypercalcemia, and lessening the risk of adynamic bone disease, with probable reduction in vascular calcification and possible reduction in mortality rate. It has a higher economic burden on health care systems compared to calcium-based phosphate binders. This may affect its extensive use according to guideline recommendations, and will be influenced by local health care budgets and the decision of health care strategists.

Randomized clinical trial of the iron-based phosphate binder PA21 in hemodialysis patients

BACKGROUND AND OBJECTIVES

A dose-finding study was undertaken to investigate the efficacy of PA21, a novel polynuclear iron(III)-oxyhydroxide phosphate binder.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In a randomized, active-controlled, multicenter, open-label study at 50 clinical sites in Europe and the United States, hemodialysis patients were randomized to PA21 at dosages of 1.25, 5.0, 7.5, 10.0, or 12.5 g/d or sevelamer-HCl 4.8 g/d for 6 weeks. The primary efficacy endpoint was the change in serum phosphorus concentration from baseline.

RESULTS

There were 154 participants who were randomized and received the study drug. All groups except PA21 1.25 g/d showed a significant decrease in serum phosphorus. Mean decreases in serum phosphorus in PA21 10 g/d and 12.5 g/d were -2.00±1.71 mg/dl and -1.69±1.81 mg/dl, respectively. A similar decrease to sevelamer-HCl (-1.06±1.35 mg/dl) was seen with PA21 5.0 g/d (-1.08±2.12 mg/dl) and 7.5 g/d (-1.25±1.21 mg/d). Overall, 60.9% of participants randomized to PA21 and 57.7% randomized to sevelamer-HCl reported ≥1 adverse event. The most frequent adverse events were hypophosphatemia (18.0%) and discolored feces (11.7%) for the pooled PA21 dose groups, and diarrhea, hypophosphatemia, and hypotension (each 11.5%) for sevelamer-HCl. Discontinuation due to adverse events occurred at a similar rate in PA21-treated (21.1%) and sevelamer-HCl-treated (23.1%) participants.

CONCLUSIONS

PA21 5-12.5 g/d significantly reduces serum phosphorus in hemodialysis patients. The 5 g/d and 7.5 g/d dosages showed similar efficacy to 4.8 g/d of sevelamer-HCl. The adverse events rate was similar for PA21 and sevelamer-HCl.

Cost-effectiveness of lanthanum carbonate versus sevelamer hydrochloride for the treatment of hyperphosphatemia in patients with end-stage renal disease: a US payer perspective

OBJECTIVE

To assess the cost-effectiveness of lanthanum carbonate (LC) versus sevelamer hydrochloride (SH) as a treatment for hyperphosphatemia in end-stage renal disease (ESRD) patients.

METHODS

A Markov model was developed to estimate health outcomes; quality-adjusted life years (QALYs) and life-years saved (LYS), as well as associated costs. The model incorporated patient-level data from a randomized head-to-head crossover study that compared the reduction of serum phosphorus using LC and SH for 4 weeks each. The model included patients previously treated with calcium-based binders. Both the intent-to-treat (ITT) population and the cohort of patients who completed treatment in both periods of the study (i.e., completer population) were assessed. The baseline risks of cardiovascular disease (CVD), all-cause mortalities for CVD, and non-CVD patients were derived from a large US renal database. Patient outcomes were modeled for 10 years, and incremental cost-effectiveness ratios (ICERs) were calculated for LC relative to SH. Deterministic and probabilistic sensitivity analyses (PSA) were performed to test the robustness of the base-case model.

RESULTS

For the ITT population, the ICERs of LC versus SH were $24,724/QALY and $15,053/LYS, respectively (in US dollars). When the completer population was considered, the ICERs of LC versus SH were $15,285/QALY and $9,337/LYS (Table 2), respectively. The PSA indicated 61.9% and 85.8% probabilities for ITT and completer populations of LC being cost-effective at the $50,000/QALY willingness-to-pay threshold, respectively.

CONCLUSION

LC is a cost-effective strategy compared with SH in the treatment of ESRD patients with hyperphosphatemia who were previously treated with calcium-based binders. Sensitivity analyses demonstrated the robustness of the pharmacoeconomic model.

Three-year extension study of lanthanum carbonate therapy in Japanese hemodialysis patients

BACKGROUND

Lanthanum carbonate is a non-aluminum, non-calcium phosphate binder. Its efficacy and its safety profile up to 1 year have been reported in Japanese hemodialysis patients.

METHODS

The present study was an extension of the earlier study. One hundred and forty-five patients were enrolled in the original 1 year observational Phase III study. After 1 year of treatment, 63 patients continued with further lanthanum treatment. Lanthanum carbonate was administered at 750-4,500 mg/day for up to 156 weeks (3 years). The reduction in serum phosphate was used to evaluate efficacy, and laboratory markers of bone turnover were monitored.

RESULTS

The serum phosphate level was maintained at a significantly lower level (P < 0.05) than the baseline level during the 3-year study period. Most of the drug-related adverse events were mild and were mainly gastrointestinal disorders. The safety profile of lanthanum during 3 years of treatment was similar to that seen in the previous study. There were no clinically relevant changes in vital signs or the electrocardiogram. Bone turnover markers, such as osteocalcin, bone-specific alkaline phosphatase, and crosslinked N-telopeptide of type I collagen, showed no clinically relevant changes.

CONCLUSION

Lanthanum therapy was able to reduce and maintain the serum phosphate level within the K/DOQI and JSDT guideline ranges in Japanese dialysis patients for 3 years.