Effect of RenaGel, a non-absorbed, calcium- and aluminium-free phosphate binder, on serum phosphorus, calcium, and intact parathyroid hormone in end-stage renal disease patients

Effects of Increased Blood Flow Rate and Oral Activated Charcoal on the Severity of Uremic Pruritus: A Randomized Crossover Clinical Trial

The aim of this study was to compare the effect of increased blood flow rate and the administration of an activated charcoal suspension on the severity of uremic pruritus in hemodialysis patients in a crossover clinical trial. Each group (n = 20) received three 2-week interventions, including increased pumping speed, daily administration of a charcoal suspension (6 g), and the concurrent use of increased pumping speed and oral administration of the charcoal suspension. After each intervention, they had a 2-week washout period. The severity and quality of pruritus were measured using the Yosipovitch's pruritus questionnaire. The results showed that the mean severity, highest pruritus score, and lowest pruritus score decreased after all three interventions, but the highest decrease was related to the third intervention. Considering the results of this study, simultaneous use of increased pumping speed and oral administration of a charcoal suspension is recommended to reduce uremic pruritus in hemodialysis patients.

Sevelamer Attenuates Bioprosthetic Heart Valve Calcification

Objective: Sevelamer hydrochloride is a phosphate binder used to treat hyperphosphatemia in chronic kidney disease (CKD) patients that can reduce valvular and vascular calcification. The aim of this study was to examine the effects of sevelamer treatment on calcification in bioprosthetic heart valves (BHVs).

Methods: Wister rats were randomly divided into three groups according to sevelamer intake and implantation (sham–sham operation; implant–implantation and normal diet, implant+S implantation, and sevelamer diet). Two kinds of BHVs—bovine pericardium treated with glutaraldehyde (GLUT) or non-GLUT techniques—were implanted in rat dorsal subcutis at 4 weeks. After implantation, sevelamer was administered to the implant+S group. The animals were executed at days 0 (immediately after implantation), 7, 14, 28, and 56. Calcium levels were determined by atomic absorption spectroscopy and von Kossa staining. Serum biochemistry analysis, Western blotting, real-time quantitative polymerase chain reaction, alkaline phosphatase activity measurement, histopathologic analysis, immunohistochemistry, and enzyme-linked immunosorbent assay were conducted to identify the anti-calcification mechanism of sevelamer.

Results: Non-GLUT crosslinking attenuates BHV calcification. Serum phosphate and calcium remained unreactive to sevelamer after a 14-day treatment. However, the mean calcium level in the implant+S group was significantly decreased after 56 days. In addition, the PTH level, inflammatory cell infiltration, system and local inflammation, and expression of Bmp2, Runx2, Alp, IL-1β, IL-6, and TNF-α were significantly reduced in the implant+S group.

Conclusion: Sevelamer treatment significantly attenuated the calcification of BHVs and had anti-inflammation effects that were independent from serum calcium and phosphate regulation. Thus, sevelamer treatment might be helpful to improve the longevity of BHVs.

Optimizing Intraoperative Blood Pressure to Improve Outcomes in Living Donor Renal Transplantation

BACKGROUND

Adequate renal perfusion at the time of unclamping is important because it has been known to affect outcomes in renal transplantation. Nevertheless, the ideal intraoperative systolic arterial pressure (SAP) has not been well defined.

METHODS

We performed a retrospective analysis of 106 living donor renal transplants performed at our center from June 2010 to May 2019. We divided the cohort into 2 groups according to our center's goal SAP of ≥150 mm Hg: 57 patients had SAP ≥150 mm Hg and 49 patients had SAP <150 mm Hg. We analyzed pretransplant characteristics, intraoperative measurements, and postoperative laboratory values to validate our center's target SAP at the time of reperfusion. This study strictly complied with the Helsinki Congress and the Istanbul Declaration regarding donor sources.

RESULTS

Patients with SAP ≥150 mm Hg had been on dialysis for a significantly shorter duration before transplant compared with those who had SAP <150 mm Hg. In the SAP ≥150 mm Hg group, urinary sodium excretion normalized earlier, and they had a significantly smaller stroke volume variation, higher cardiac output and cardiac index, earlier initial urination, and higher intraoperative urine output. There were no differences in intraoperative volume repletion, central venous pressure, or postoperative estimated glomerular filtration rate.

CONCLUSION

Achieving SAP ≥150 mm Hg at the time of reperfusion may be associated with early stabilization of graft function. Nevertheless, our data suggested that recipients with a prolonged dialysis history are less likely to achieve SAP ≥150 mm Hg at the time of unclamping in living donor renal transplantation.

Sevelamer Hydrochloride in Peritoneal Dialysis Patients: Results of a Multicenter Cross-Sectional Study

Background

Sevelamer hydrochloride is a phosphate binder widely employed in hemodialysis patients. Until now, information about its efficacy and safety in peritoneal dialysis patients has been scarce.

Patients and Methods

In September 2005 a cross-sectional study of demographic, biochemical, and therapeutic data of patients from 10 peritoneal dialysis units in Catalonia and the Balearic Islands, Spain, was conducted.

Results

We analyzed data from 228 patients. At the time of the study, 128 patients (56%) were receiving sevelamer. Patients receiving sevelamer were younger ( p < 0.01), showed a longer period of time on dialysis ( p < 0.01), and had a lower Charlson Comorbidity Index ( p < 0.01). Serum calcium and intact parathyroid hormone levels were not different between the two groups, while phosphate levels <5.5 mg/dL were observed more frequently in patients not receiving sevelamer (79% vs 61%, p < 0.01). Serum total cholesterol (167 ± 41 vs 189 ± 42 mg/dL, p < 0.01) and low density lipoprotein (LDL) cholesterol (90 ± 34 vs 109 ± 34 mg/dL, p < 0.01), but not high density lipoprotein cholesterol or triglycerides, were lower in sevelamer-treated patients. Moreover, sevelamer-treated patients displayed a higher serum albumin (38 ± 5 vs 36 ± 4 g/L, p < 0.01) and a lower C-reactive protein (4.9 ± 12.8 vs 8.8 ± 15.7 mg/L, p < 0.01). Blood bicarbonate levels <22 mmol/L were observed more frequently in patients receiving sevelamer (22% vs 5%, p < 0.01). Logistic regression analysis adjusting by confounding variables confirmed that sevelamer therapy was associated with serum total cholesterol <200 mg/dL [relative risk (RR): 2.77, 95% confidence interval (CI): 1.44 – 5.26, p = 0.002] and blood bicarbonate <22 mmol/L (RR: 8.5, 95% CI: 2.6 – 27.0, p < 0.001), but not with serum phosphate >5.5 mg/dL, calcium–phosphate product >55 mg2/dL2, serum albumin <35 g/L, or C-reactive protein >5 mg/L.

Conclusions

This uncontrolled cross-sectional study in peritoneal dialysis patients showed that sevelamer hydro-chloride treatment allows an adequate serum phosphate level in about 60% of patients and significantly reduces total and LDL-cholesterol levels. Since this treatment is associated with metabolic acidosis in 22% of patients, we recommend close monitoring of bicarbonate levels in this group of patients until the clinical significance of this result is clarified.

Sevelamer Hydrochloride versus Aluminum Hydroxide: Effect on Serum Phosphorus and Lipids in CAPD Patients

Background

Dietary phosphorus restriction, oral administration of phosphorus binders, and dialysis are the main strategies to control hyperphosphatemia in patients with stage 5 chronic kidney disease. Aluminum hydroxide (AH) and calcium carbonate, the most commonly used phosphorus binders, have serious disadvantages, such as aluminum toxicity and hypercalcemia. Sevelamer hydrochloride (SH) is a relatively new nonabsorbed calcium- and aluminum-free phosphorus binder. The present study was designed to evaluate the efficacy of SH in the control of hyperphosphatemia and its effect, compared to AH, on serum lipid parameters in patients on continuous ambulatory peritoneal dialysis (CAPD).

Methods

30 stable patients on CAPD were included in an open-label, randomized crossover study. After a 2-week phosphorus binder washout period, 15 patients (group I) were administered SH for 8 weeks and in the remaining patients (group II), AH was introduced (phase A). After a new 2-week washout period, patients crossed over to the alternate agent for another 8 weeks (phase B).

Results

There were similar reductions in serum phosphorus levels over the course of the study with both agents: by 1.18 ± 0.07 mg/dL (0.38 ± 0.03 mmol/L) with SH and by 1.25 ± 0.15 mg/dL (0.40 ± 0.05 mmol/L) with AH in phase A ( p = NS), and by 1.35 ± 0.25 mg/dL (0.43 ± 0.08 mmol/L) with AH and by 1.23 ± 0.80 mg/dL (0.39 ± 0.25 mmol/L) with SH in phase B ( p = NS). Moreover, SH administration was associated with a 10.5% ± 9.4% and a 20.1% ± 6.8% fall in total cholesterol ( p < 0.05) and low-density lipoprotein cholesterol ( p < 0.001) in phase A, and 11.9% ± 7.2% ( p < 0.05) and 21.5% ± 2.4% ( p < 0.001), respectively, in phase B. In both phases of the study, AH administration was not followed by a significant change in serum lipid parameters.

Conclusion

Sevelamer hydrochloride is a well-tolerated alternative to calcium- or aluminum-containing phosphorus binder in the control of serum phosphorus in CAPD patients. Furthermore, SH improves the lipid profile in these patients.

Sevelamer hydrochloride suppresses proliferation of parathyroid cells during the early phase of chronic renal failure in rats

AIM

We examined the effects of sevelamer on parathyroid cell proliferation and secondary hyperparathyroidism in rats following induction of early-phase of chronic renal failure (CRF) by unilateral ureteral obstruction (UUO).

METHODS

For 5 days, rats in the control group received normal food, rats in the sevelamer group (SH) received control food plus 5% sevelamer, and rats in the low protein group (LP) received low protein food. Five rats of each group were killed at baseline (day 0). All other rats were given UUO, and five rats per group were killed on days 3, 7, 14, and 28 after UUO. Changes in body weight, serum phosphorus, calcium, intact-parathyroid hormone (i-PTH), creatinine (SCr), creatinine clearance rate (CCR), blood urea nitrogen (BUN), and 24-h urinary phosphorus were determined. Parathyroid tissues were removed for histological examination of proliferating cell nuclear antigen-positive (PCNA+) cells.

RESULTS

Measurement of body weight, BUN, and SCr in the controls indicated successful establishment of this model of early-phase CRF. The controls also had remarkable proliferation of PCNA+ cells beginning on day 3, but this did not occur in the SH or LP groups. After 28 days, serum phosphorus had decreased more in the SH and LP groups than in the control group, and phosphorus excretion was much greater in the control group than in the SH and LP groups. The three groups had similar increases in serum i-PTH.

CONCLUSION

Sevelamer rapidly lowered the serum phosphorus and inhibited the proliferation of PCNA+ cells in this experimental model of early-phase CRF.

Effects of Sevelamer Hydrochloride on Uremic Toxins Serum Indoxyl Sulfate and P-Cresyl Sulfate in Hemodialysis Patients

Background

Beside the phosphate binding effect, non-calcium non-aluminum phosphate binder, namely sevelamer hydrochloride (SH), has many other effects in dialysis patients. It can absorb many other compounds, decrease low-density lipoprotein cholesterol (LDL-C) level, and attenuate the progression of vascular calcification; it has been reported to have anti-inflammatory effect. However, it is not clear whether it has any effect on uremic toxins, i.e. serum indoxyl sulfate (IS) and p-cresyl sulfate, (PCS) in hemodialysis (HD) patients. This study was carried out to appraise the effect of sevelamer on serum IS and PCS in HD patients.

Methods

Five adult HD patients from a single medical center were enrolled in this study; these patients were treated with 800 mg of sevelamer thrice per day for 3 months; a series of biochemical parameters, serum IS and PCS were monitored concurrently.

Results

There was a significant reduction in the mean level of phosphate from 7.20 ± 0.70 mg/dL (mean ± SD) before treatment to 5.40 ± 0.50 mg/dL (mean ± SD) after treatment, total cholesterol from 151.00 ± 37.40 mg/dL (mean ± SD) before treatment to 119.20 ± 29.40 mg/dL (mean ± SD) after treatment, and PCS from 31.30 ± 10.60 mg/L (mean ± SD) before treatment to 19.70 ± 10.50 mg/L (mean ± SD) after treatment. On the contrary, this treatment had no effect on IS.

Conclusion

A statistically significant reduction of serum phosphate and PCS in HD patients treated with SH suggests that beside the action of lowering serum phosphate, sevelamer may have an important role in the treatment of uremic syndrome by decreasing the uremic toxin.

Pharmacological Management of Secondary Hyperparathyroidism in Patients with Chronic Kidney Disease

Secondary hyperparathyroidism (SHPT) is a common complication of chronic kidney disease (CKD) and is part of the CKD-mineral bone disorder (CKD-MBD). SHPT is associated with increased risk of fracture and mortality; thus, SHPT control is recommended as kidney function declines. Effective SHPT management becomes more difficult once skeletal and cardiovascular adverse effects associated with severe SHPT have become established. However, interventional studies to lower parathyroid hormone (PTH) have so far shown inconsistent results in improving patient-centred outcomes such as mortality, cardiovascular events and fracture. Pharmacological treatment effect on PTH level is also inconsistent between pre-dialysis CKD and dialysis patients, which adds to the complexity of SHPT management. This review aims to give an overview on the pathophysiology, pharmacological and non-pharmacological treatment for SHPT in CKD including some of the limitations of current therapeutic options.

Bicarbonate Balance and Prescription in ESRD

The optimal approach to managing acid-base balance is less well defined for patients receiving hemodialysis than for those receiving peritoneal dialysis. Interventional studies in hemodialysis have been limited and inconsistent in their findings, whereas more compelling data are available from interventional studies in peritoneal dialysis. Both high and low serum bicarbonate levels associate with an increased risk of mortality in patients receiving hemodialysis, but high values are a marker for poor nutrition and comorbidity and are often highly variable from month to month. Measurement of pH would likely provide useful additional data. Concern has arisen regarding high-bicarbonate dialysate and dialysis-induced alkalemia, but whether these truly cause harm remains to be determined. The available evidence is insufficient for determining the optimal target for therapy at this time.

Effect of Tenapanor on Serum Phosphate in Patients Receiving Hemodialysis

Hyperphosphatemia is common among patients with CKD stage 5D and is associated with morbidity and mortality. Current guidelines recommend lowering serum phosphate concentrations toward normal. Tenapanor is a minimally absorbed small molecule inhibitor of the sodium/hydrogen exchanger isoform 3 that functions in the gut to reduce sodium and phosphate absorption. This randomized, double-blind, placebo-controlled trial assessed the effects of tenapanor on serum phosphate concentration in patients with hyperphosphatemia receiving hemodialysis. After a 1- to 3-week washout of phosphate binders, we randomly assigned 162 eligible patients (serum phosphate =6.0 to <10.0 mg/dl and a 1.5-mg/dl increase from before washout) to one of six tenapanor regimens (3 or 30 mg once daily or 1, 3, 10, or 30 mg twice daily) or placebo for 4 weeks. The primary efficacy end point was change in serum phosphate concentration from baseline (randomization) to end of treatment. In total, 115 patients (71%) completed the study. Mean serum phosphate concentrations at baseline (after washout) were 7.32-7.92 mg/dl for tenapanor groups and 7.87 mg/dl for the placebo group. Tenapanor provided dose-dependent reductions in serum phosphate level from baseline (least squares mean change: tenapanor =0.47-1.98 mg/dl; placebo =0.54 mg/dl; P=0.01). Diarrhea was the most common adverse event (tenapanor =18%-68%; placebo =12%) and frequent at the highest tenapanor doses. In conclusion, tenapanor treatment resulted in statistically significant, dose-dependent reductions in serum phosphate concentrations in patients with hyperphosphatemia receiving hemodialysis. Additional studies are required to clarify the optimal dosing of tenapanor in patients with CKD-related hyperphosphatemia.

Feasibility study of colestipol as an oral phosphate binder in hemodialysis patients

BACKGROUND

Currently available calcium- and aluminium-based phosphate binders are dose limited because of potential toxicity, and newer proprietary phosphate binders are expensive. We examined phosphate-binding effects of the bile acid sequestrant colestipol, a non-proprietary drug that is in the same class as sevelamer.

METHODS

The trial was an 8 week prospective feasibility study in stable hemodialysis patients using colestipol as the only phosphate binder, preceded and followed by a washout phase of all other phosphate binders. The primary study endpoint was weekly measurements of serum phosphate. Secondary endpoints were serum calcium, lipids and coagulation status. Analyses used random effects mixed models.

RESULTS

Thirty patients were screened for participation of which 26 met criteria for treatment. At a mean dose of 8.8 g/24 h of colestipol by study end, serum phosphate dropped from 2.24 to 1.96 mmol/L (P < 0.001). Three patients required calcium supplementation. LDL cholesterol dropped from 1.75 to 1.2 mmol/L (P < 0.001). Three patients dropped out because of side effects or intolerance of the required dose.

CONCLUSION

The results support the feasibility of a larger trial to determine the efficacy of colestipol as a phosphate binder and that other non-proprietary anion-exchange resins may also warrant investigation.

Variability in monthly serum bicarbonate measures in hemodialysis patients: a cohort study

Background

Some nephrologists have advocated an individualized approach to the prescription of bicarbonate hemodialysis. However, the utility of monthly serum bicarbonate levels for guiding and evaluating such treatment decisions has not been evaluated. We sought to define the variability of these measurements and to determine factors that are associated with month-to-month variability in pre-dialysis serum bicarbonate.

Methods

We examined the monthly variability in serum bicarbonate measurements among 181 hemodialysis patients admitted to a free-standing dialysis unit in the Bronx, NY from 1/1/2008-6/30/2012. All patients were treated with a uniform bicarbonate dialysis prescription (bicarbonate 35 mEq/L, acetate 8 mEq/L). Pre-dialysis serum bicarbonate values were obtained from monthly laboratory reports. Month-to-month variability was defined using a rolling measurement for each time point.

Results

Only 34 % of high serum bicarbonate values (>26 mEq/L) remained high in the subsequent month, whereas 60 % converted to normal (22–26 mEq/L). Of all low values (<22 mEq/L), 41 % were normal the following month, while 58 % remained low. Using the mean 3-month bicarbonate, only 29 % of high values remained high in the next 3-month period. In multivariable-adjusted longitudinal models, both low and high serum bicarbonate values were associated with greater variability than were normal values (β = 0.12 (95 % CI 0.09–0.15) and 0.24 (0.18 to 0.29) respectively). Variability decreased with time, and was significantly associated with age, phosphate binder use, serum creatinine, potassium, and normalized protein catabolic rate.

Conclusions

Monthly pre-dialysis serum bicarbonate levels are highly variable. Even if a clinician takes no action, approximately 50 % of bicarbonate values outside a normal range of 22–26 mEq/L will return to normal in the subsequent month. The decision to change the bicarbonate dialysis prescription should not be based on a single bicarbonate value, and even a 3-month mean may be insufficient.

Electronic supplementary material

The online version of this article (doi:10.1186/s12882-015-0206-2) contains supplementary material, which is available to authorized users.

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.

A randomized, double-blind, placebo-controlled, dose-ranging study using Genz-644470 and sevelamer carbonate in hyperphosphatemic chronic kidney disease patients on hemodialysis

Background

Genz-644470 is a new, nonabsorbed phosphate binding polymer. In an in vitro competitive phosphate binding assay, Genz-644470 bound significantly more phosphate per gram than sevelamer. As a consequence, this clinical study evaluated the ability of Genz-644470 to lower serum phosphorus in patients on hemodialysis and compared serum phosphorus lowering of Genz-644470 with sevelamer carbonate and placebo. Because three different fixed doses of Genz-644470 and sevelamer carbonate were used, phosphate-lowering dose-responses of each agent were also analyzed.

Methods

A randomized, double-blind, dose-ranging study was conducted. After a 2-week phosphate binder washout, 349 hyperphosphatemic (serum phosphorus >5.5 mg/dL) hemodialysis patients were randomized to one of seven fixed-dose groups: placebo, Genz-644470 2.4 g/day, Genz-644470 4.8 g/day, Genz-644470 7.2 g/day, sevelamer carbonate 2.4 g/day, sevelamer carbonate 4.8 g/day, or sevelamer carbonate 7.2 g/day. Indicated total daily doses were administered in fixed divided doses three times a day with meals for 3 weeks. The change in serum phosphorus during the treatment period and its dose-response patterns were assessed.

Results

Dose-dependent reductions in serum phosphorus were observed with both Genz-644470 and sevelamer carbonate. Serum phosphorus-lowering responses to fixed doses of sevelamer carbonate and Genz-644470 were enhanced in a roughly linear fashion with increasing doses over a threefold range after 3 weeks of treatment. Genz-644470 did not show any advantage in phosphorus lowering per gram of binder compared with sevelamer carbonate. Overall toler-ability was similar between active treatment groups. The tolerability of sevelamer carbonate was consistent with prior studies and with the established safety profile of sevelamer.

Conclusion

Both Genz-644470 and sevelamer carbonate effectively lowered serum phosphate levels in a dose-dependent fashion in patients with chronic kidney disease on hemodialysis. However, Genz-644470 did not provide any advantage over sevelamer carbonate in phosphate lowering in vivo, as had been demonstrated in vitro.

Sevelamer carbonate lowers serum phosphorus effectively in haemodialysis patients: a randomized, double-blind, placebo-controlled, dose-titration study

BACKGROUND

Hyperphosphataemia in patients with advanced chronic kidney disease (CKD) is associated with adverse outcomes, including vascular calcification and higher mortality rates. While phosphate lowering is an integral aspect of CKD management, the efficacy and safety of phosphate binders in a contemporary cohort of Chinese haemodialysis patients (who have different genetics and dietary patterns than other populations) has not been previously described. Moreover, sparse data are available on strategies for optimal dose titration when transitioning from a calcium-based to a polymer-based phosphate binder.

METHODS

This randomized, double-blind, dose-titration study compared sevelamer carbonate (starting dose 800 mg three times daily) with placebo over 8 weeks' duration in Chinese CKD patients on haemodialysis. Patients were required to be using calcium-based binders prior to study start.

RESULTS

In all, 205 patients were randomized (sevelamer, n = 135; placebo, n = 70); mean age was 48.6 years, 61% were male and the mean time on dialysis was 4.4 years. The mean serum phosphorus decreased significantly in patients treated with sevelamer carbonate [change -0.69 ± 0.64 mmol/L (-2.14 ± 1.98 mg/dL)] but remained persistently elevated with placebo [change -0.06 ± 0.57 mmol/L (-0.19 ± 1.76 mg/dL)] (P < 0.0001). When compared with placebo, sevelamer carbonate treatment resulted in statistically significant greater mean reductions from baseline in serum total (-17.1 versus -3.3%) and low-density lipoprotein cholesterol (-33.5 versus-7.6%) (P < 0.0001 for both). Sevelamer carbonate was well tolerated with 96% adherence compared with 97% adherence in the placebo arm. Overall, adverse events experienced by patients in the sevelamer carbonate and placebo treatment groups were similar and consistent with their underlying renal disease.

CONCLUSIONS

This study demonstrated that hyperphosphataemia developed quickly following the cessation of phosphate binders and remained persistently elevated in end-stage CKD in the placebo-treated group. Gradually titrating up sevelamer carbonate from an initial dose of 2.4 g/day to an average daily dose of 7.1 ± 2.5 g/day was well tolerated, safe and efficacious in contemporary Chinese haemodialysis patients.

Sevelamer hydrochloride dose-dependent increase in prevalence of severe acidosis in hemodialysis patients: analysis of nationwide statistical survey in Japan

Metabolic acidosis has a negative impact on prognosis of dialysis patients. The aim of this study was to determine the prevalence of severe metabolic acidosis in dialysis patients treated with sevelamer hydrochloride. In 2004, a nationwide survey (101,516 dialysis patients) was conducted by the Japanese Society for Dialysis Therapy. We analyzed 32,686 dialysis patients whose bicarbonate levels were measured in the survey. Sevelamer hydrochloride was prescribed to 9231 dialysis patients while 23,455 dialysis patients were not prescribed sevelamer hydrochloride. In the present study, we defined severe acidosis as bicarbonate <15.8 mmol/L. The mean serum bicarbonate level correlated significantly and negatively with the daily dose of sevelamer hydrochloride (R(2) = 0.806, P < 0.0001). Logistic regression analysis indicated that the percentage of patients with severe acidosis increased significantly with increased dose of sevelamer hydrochloride (R(2) = 0.885, P < 0.00001). The estimated doses of sevelamer hydrochloride associated with severe acidosis in 10% and 15% of patients were 3.5 g/day (95% confidence interval [95%CI], 2.8-4.4) and 7.7 g/day (95%CI = 5.9-10.9), respectively. Severe acidosis was noted in 4.5% of patients who were not treated with sevelamer hydrochloride and in 16.1% of patients treated with sevelamer hydrochloride at ≥ 5.25 g/day (P < 0.0001). The results call for careful monitoring of serum bicarbonate level in hemodialysis patients treated with sevelamer hydrochloride.

Sevelamer and the bone-vascular axis in chronic kidney disease: bone turnover, inflammation, and calcification regulation

Hyperphosphatemia is a central characteristic feature of chronic kidney disease-mineral and bone disorder (CKD-MBD). Phosphorus excess is an independent cardiovascular risk factor for morbidity and mortality in patients with advanced CKD. Over the past 40 years, hyperphosphatemia has been a central therapeutic issue in advanced CKD. Mainstays of hyperphosphatemia treatment are reduction of dietary phosphorus, use of phosphate binders, and optimized phosphorus removal via dialysis. Currently, several phosphate binders are approved for use (aluminum, calcium, lanthanum, sevelamer); all share a common functionality in that they bind phosphorus and reduce the amount absorbed in the gastrointestinal lumen. Over the last decade, nephrologists have debated the relative tolerability and efficacy of these agents, especially the potential for vascular calcification and cardiovascular risk reduction. Recent research has focused on the question of whether a metal-free, calcium-free, and non-absorbed binder, such as sevelamer, offers advantages over other binder types. Most notable may be the potential benefit of reducing calcium load. In addition, sevelamer has several additional pleiotropic effects that may extend its basic indication, some of which may help attenuate vascular calcification. These include effects on bone turnover and the link between abnormal vascular processes and bone metabolism (the so-called 'bone-vascular axis'), as well as lipid metabolism, and systemic inflammatory mediators such as fetuin-A. We review the evidence for these pleiotropic effects, and suggest these may help in some way to improve the substantial disease burden in the CKD-MBD population.

A randomized, parallel, open-label study to compare once-daily sevelamer carbonate powder dosing with thrice-daily sevelamer hydrochloride tablet dosing in CKD patients on hemodialysis

BACKGROUND

Sevelamer carbonate powder for oral suspension is a new dosage form of sevelamer, which may be suited to once-daily dosing.

STUDY DESIGN

Randomized parallel open-label study.

SETTING & PARTICIPANTS

Hemodialysis patients.

INTERVENTION

After a 2-week phosphate-binder washout, patients were randomly assigned to once-daily sevelamer carbonate powder or thrice-daily sevelamer hydrochloride tablets.

OUTCOMES

Assessment of noninferiority with respect to change from baseline in serum phosphorus levels.

MEASUREMENTS

Serum phosphorus to 24 weeks.

RESULTS

After washout, mean serum phosphorus level decreased 2.0 +/- 1.8 mg/dL (from 7.3 +/- 1.3 mg/dL) for sevelamer carbonate and 2.9 +/- 1.3 mg/dL (from 7.6 +/- 1.3 mg/dL) for sevelamer hydrochloride (both P < 0.001). The upper CI bound was 1.50 mg/dL; therefore, noninferiority was not shown. 54% of sevelamer carbonate powder-treated patients and 64% of sevelamer hydrochloride tablet-treated patients had serum phosphorus levels within the National Kidney Foundation's Kidney Disease Outcomes Quality Initiative (KDOQI) target (> or =3.5 and < or =5.5 mg/dL). Overall, the percentage of patients with treatment-emergent adverse events was similar between groups. However, a greater percentage of treatment-related upper gastrointestinal events, including nausea (10% vs 3%) and vomiting (6% vs 1%), were noted with sevelamer carbonate powder once daily. In addition, 4 (3%) sevelamer carbonate-treated patients experienced stimulation of the gag reflex and 2 (1%) experienced dislike of the taste with sevelamer carbonate powder. A greater percentage of sevelamer carbonate powder-treated patients discontinued treatment because of these treatment-related events or consent withdrawal.

LIMITATIONS

Study was not blinded. Once-daily dose may not have been with the highest phosphate content meal; further exploration of alternative dosing schemes is warranted.

CONCLUSIONS

Once-daily administration of sevelamer carbonate powder was not as effective in decreasing serum phosphorus levels as thrice-daily administration of sevelamer hydrochloride tablets. Nevertheless, once-daily sevelamer carbonate powder decreased serum phosphorus levels significantly, reaching the KDOQI phosphorus target in most patients. Therefore, once-daily dosing of sevelamer carbonate may be a reasonable alternative.

Short-term efficacy of sevelamer versus calcium acetate in patients with chronic kidney disease stage 3-4

BACKGROUND

The relative effectiveness and safety of sevelamer, a mineral-free phosphate binder, for treatment of hyperphosphatemia in children with chronic kidney disease is uncertain.

AIM

This study was designed to compare the efficacy and acceptability of sevelamer hydrochloride to calcium acetate as a phosphate binder in pediatric patients with chronic kidney disease.

METHODS

A 12-week open-label trial of sevelamer hydrochloride vs calcium acetate was initiated in 22 patients, aged 2-18, with CKD stages 3 and 4. After a 2-week washout of phosphate binders and vitamin D, patients were randomized to receive sevelamer hydrochloride or calcium acetate. The effect of therapy was adjusted for baseline blood levels of calcium, phosphorus, calcium-phosphate product, alkaline phosphatase, PTH and GFR using ANOVA. The primary end point was the decrease in serum phosphorus levels after 12 weeks of treatment.

RESULTS

Of the 22 patients enrolled, data of 19 patients were used for analysis. The adjusted mean serum phosphate levels at 12 weeks did not differ significantly between calcium acetate- (5.3 mg/dl) and sevelamer-treated subjects (6.1 mg/dl) (P adjusted means = 0.6). The adjusted blood level of calcium at 12 weeks was significantly lower in the sevelamer-treated patients (8.2 mg/dl) compared to those treated with calcium acetate (9.1 mg/dl) (P adjusted means = 0.01). In the sevelamer group, there was a non-significant decrease in serum bicarbonate, whereas the total and LDL cholesterol significantly decreased at 12 weeks (P = 0.04). Sevelamer hydrochloride was well tolerated and without adverse effects related to the drug.

CONCLUSIONS

Compared to calcium acetate, use of sevelamer in children with chronic kidney disease is associated with similar reduction in serum phosphate levels, lower risk of hypercalcemia, and marked decrease in serum lipid levels.

Treatment Options for Hyperphosphatemia in Feline CKD: What's Out there?

Practical relevance Phosphorus is retained in chronic kidney disease (CKD), promoting renal secondary hyperparathyroidism and eventually resulting in hyperphosphatemia. Most agree that phosphate retention is a major contributor to the progression of CKD in many species and it is well known that hyperphosphatemia is associated with a significant mortality risk in humans with end-stage renal disease.

Patient group Chronic kidney disease is a common ailment of geriatric cats.

Evidence base There is evidence in cats suggesting that the use of a phosphate-restricted diet in IRIS stage 2–3 disease has a beneficial effect on clinical outcome. However, despite the fact that intestinal phosphate binders are commonly used in veterinary practice for patients with CKD, there have been few published reports focusing on the safety and efficacy of these products in veterinary medicine. No phosphorus binders are licensed as medications for dogs or cats. This article draws on data from clinical trials in humans and studies in cats to discuss treatment goals and options for phosphate retention and hyperphosphatemia in feline CKD.

Clinical significance With careful monitoring of serum phosphate and parathyroid hormone, and implementation of phosphate-restricted dietary management and intestinal phosphate binders, progression of CKD and the degree of hyperparathyroidism in cats may be reduced.

Audience Companion animal and feline practitioners are at the forefront in the management of CKD in cats.

A randomized, crossover design study of sevelamer carbonate powder and sevelamer hydrochloride tablets in chronic kidney disease patients on haemodialysis

Background. Sevelamer carbonate is an improved, buffered form of sevelamer hydrochloride developed for the treatment of hyperphosphataemia in CKD patients. Sevelamer carbonate formulated as a powder for oral suspension presents a novel, patient-friendly alternative to tablet phosphate binders. This study compared the safety and efficacy of sevelamer carbonate powder with sevelamer hydrochloride tablets in CKD patients on haemodialysis.

Methods. This was a multi-centre, open-label, randomized, crossover design study. Thirty-one haemodialysis patients were randomly assigned to either sevelamer carbonate powder or sevelamer hydrochloride tablets for 4 weeks followed by a crossover to the other regimen for an additional 4 weeks.

Results. The mean serum phosphorus was 1.6 ± 0.5 mmol/L (5.0 ± 1.5 mg/dL) during sevelamer carbonate powder treatment and 1.7 ± 0.4 mmol/L (5.2 ± 1.1 mg/dL) during sevelamer hydrochloride tablet treatment. Sevelamer carbonate powder and sevelamer hydrochloride tablets are equivalent in controlling serum phosphorus; the geometric least square mean ratio was 0.95 (90% CI 0.87–1.03). No statistically significant or clinically meaningful differences were observed in calcium × phosphorus product and lipid levels between sevelamer carbonate powder and sevelamer hydrochloride tablets. Serum bicarbonate levels increased 2.7 ± 3.7 mmol/L (2.7 ± 3.7 mEq/L) during sevelamer carbonate treatment. No statistically significant change in bicarbonate was observed during sevelamer hydrochloride treatment. Sevelamer carbonate powder and sevelamer hydrochloride were well tolerated during this study.

Conclusions. Sevelamer carbonate powder and sevelamer hydrochloride tablets are equivalent in controlling serum phosphorus and well tolerated in CKD patients on haemodialysis. Bicarbonate levels improved only during sevelamer carbonate treatment. Sevelamer carbonate powder should provide a welcomed new option for the treatment of hyperphosphataemia for CKD patients on dialysis.

A 44 year-old lady with chronic renal disease and intractable ulcers: a case report

Calciphylaxis is a rare but potentially fatal condition occurring in patients with end stage renal disease on dialysis. Due to interplay of various factors, disturbances occur in the metabolism of calcium and phosphate leading to calcification within the vessel walls. The net result is tissue ischemia and necrosis. Clinically this presents as painful non-healing skin ulcers, which contribute to significant morbidity and mortality due to septic progression of the lesion. In this case report, we highlight the rapidly progressive nature of this disease, its etiopathogenesis and the role of early diagnosis in preventing life-threatening complications.

Oral phosphate binders: history and prospects

The use of an oral phosphate binder is a promising and most practical strategy for the prevention of vascular calcification in patients with chronic kidney disease (CKD). To secure the safety: 1) the oral phosphate binder must not cause adverse effects in the gastrointestinal tract; 2) the oral phosphate binder should be non-absorbable or barely absorbable through the gastrointestinal tract, or 3) if partially absorbed through the gastrointestinal tract, it must be eliminated from circulation through a pathway other than urinary excretion, and 4) even if it accumulates in the body, it should not cause organ dysfunctions. Metal salt type oral phosphate binder is the most classical type of oral phosphate binders that includes aluminum hydroxide gel and lanthanum carbonate. These oral phosphate binders effectively adsorb phosphate ions, however, have a potential risk for accumulation and intoxication. Calcium salt type oral phosphate binder was the most widely prescribed oral phosphate binder in the last decade but is now believed to exert potential harm, favoring progression of vascular calcification through excessive intestinal calcium load. However, recent studies failed to detect an inferiority of calcium salt type oral phosphate binders as compared to non-calcium salt type oral phosphate binders in terms of mortality and/or morbidity of hemodialysis patients. Polymerized resin type is a safe and relatively effective oral phosphate binder, which is supported by many clinical evidences. However, it sometimes causes severe constipation, especially in Japanese patients. Among metal compound type oral phosphate binder, other promising compounds include boehmite-type aluminum and hydrotalcite-like compounds but they are not yet available in the clinical setting.

Effect of sevelamer hydrochloride on bone in experimental uremic rats

Hyperphosphatemia in dialysis patients is known to cause secondary hyperparathyroidism and high-turnover bone disease. Sevelamer hydrochloride (sevelamer) is a nonabsorbed, calcium-free phosphate-binder. We determined the effect of sevelamer on parathyroid hormone (PTH)-induced high bone turnover. Rats were sham-operated or 5/6-nephrectomized (Nx) and fed a phosphate loading diet for 16 weeks or 5/6-nephrectomized and fed a phosphate loading diet for 8 weeks and then fed the same diet containing 3% sevelamer for the subsequent 8 weeks (Nx-S). Sevelamer significantly reduced serum PTH. The relative osteoid volume (OV/BV), osteoid surface (OS/BS), eroded surface (ES/BS), mineral appositional rate (MAR), volume-referent bone formation rate (BFR/TV), and bone-referent bone formation rate (BFR/BV) were measured for vertebral bone histomorphometric analysis. All parameters were statistically higher in the Nx rats than in the sham-operated control rats. The administration of sevelamer attenuated increases in OV/BV, ES/BS, BFR/TV, and BFR/BV. For femur histomorphometric analysis, the porosity area (%) (PoAr/CtAr), osteoid surface on the periosteal surface, osteoid surface on the endocortical surface (OS/Es), mineral appositional rate on the periosteal surface, mineral appositional rate on the endocortical surface, bone formation rate on the periosteal surface, and bone formation rate on the endocortical surface (Es BFR) were calculated. All parameters were higher in the Nx group than in the control group. Sevelamer inhibited the elevation of PoAr/CtAr, OS/Es, and Es BFR. Our findings suggest that the decrease in PTH by sevelamer may be beneficial in the treatment of high PTH-induced bone disease.

Efficacy and tolerability of sevelamer carbonate in hyperphosphatemic patients who have chronic kidney disease and are not on dialysis

BACKGROUND AND OBJECTIVES

Sevelamer carbonate is an improved, buffered form of sevelamer hydrochloride developed for the treatment of hyperphosphatemia in patients with chronic kidney disease. This study investigated the ability of sevelamer carbonate to control serum phosphorous in hyperphosphatemic patients who had chronic kidney disease and were not on dialysis.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This was an open-label, dosage-titration study. Patients with serum phosphorus > or =5.5 mg/dl were enrolled (n = 46). Sevelamer carbonate was administered for 8 wk. Patients were supplemented with native vitamin D (400 IU). The primary efficacy parameter was the change from baseline in serum phosphorous. Secondary measures included the percentage of serum phosphorus responders; changes in serum lipids, calcium-phosphorus product, and bicarbonate; and safety and tolerability.

RESULTS

Sevelamer carbonate treatment resulted in a statistically significant decrease in mean serum phosphorous levels from baseline to end of treatment. A total of 75% of patients with stage 4 and 70% of patients with stage 5 chronic kidney disease achieved the target serum phosphorous at the end of treatment. There were statistically significant decreases in serum calcium-phosphorus product and total and low-density lipoprotein cholesterol at the end of treatment and a statistically significant increase in mean serum bicarbonate levels (from 16.6 to 18.2 mEq/L). Sevelamer carbonate was well tolerated.

CONCLUSIONS

Sevelamer carbonate is an effective and well-tolerated therapy for the control of phosphorous levels in hyperphosphatemic patients who have chronic kidney disease and are not on dialysis.

Sevelamer hydrochloride: a novel treatment of hyperphosphatemia associated with tumor lysis syndrome in children

BACKGROUND

Sevelamer is a phosphate-binder used effectively for the treatment of hyperphosphatemia in patients treated with dialysis.

OBJECTIVES

To describe the safety of sevelamer in children with hyperphosphatemia secondary to tumor lysis syndrome and the serum phosphate concentrations observed following its administration.

PROCEDURE

A retrospective chart review of all children with leukemia/lymphoma diagnosed between November 2002 and April 2004 who received sevelamer during their initial admission was conducted. We monitored the effects of sevelamer on serum phosphate concentration, calcium/phosphate product and renal function at hours 24, 48, and 72 from sevelamer initiation.

RESULTS

Thirteen patients received sevelamer during the study period. Their median age was 13 years (range 2.7-17.9) and eight were boys. Nine children had acute lymphoblastic leukemia, one had acute myeloid leukemia and 3 had non-Hodgkin's lymphoma. The most frequently used dose of sevelamer was 400 mg orally twice daily. The median duration of sevelamer therapy was 2 days (range 1-7). Two children were excluded from the efficacy analysis due to concurrent use of dialysis. Mean serum phosphate levels decreased after sevelamer administration, in eleven patients, from a baseline 2.2 mmol/L +/- 0.4 (95% CI, 1.7-3.1) to 1.1 mmol/L +/- 0.2 at hour 72 (95%CI, 0.6-1.5). The only toxicity attributed to sevelamer was mild vomiting in three patients.

CONCLUSIONS

Sevelamer appears to be effective and tolerable for the treatment of hyperphosphatemia associated with tumor lysis syndrome.

Lanthanum carbonate as a first-line phosphate binder: the "cons"

Controlling serum phosphorus levels in patients with renal failure is critical. The use of oral phosphate-binding agents is universal for patients with end-stage kidney disease to reduce phosphate absorption. The therapeutic goal is to reduce serum phosphorus levels without disturbing calcium homeostasis or promoting accumulation of potentially toxic elements from the medication. Aluminum hydroxide effectively reduces serum phosphorus, but has largely been abandoned as a first-line phosphate binder because of hazards associated with metal absorption and tissue accumulation. Traditional calcium-based phosphate binders tend to promote hypercalcemia and calcium overloading, and are linked to accelerated cardiovascular calcification. Interest in aluminum-free, calcium-free phosphate-binding agents continues to grow. Sevelamer hydrochloride, a metal-free, calcium-free hydrogel, is not absorbed, has been proven safe and efficacious in controlling serum phosphorus, and is associated with attenuated progression of cardiovascular calcification. Lanthanum carbonate is a newer aluminum-free, calcium-free phosphate-binding agent. Lanthanum is a rare-earth trace metal with industrial and agricultural applications. As a therapeutic, this metal-based binder appears effective in reducing serum phosphorus, yet concerns remain about lanthanum accumulation in tissues during long-term oral administration. Similar to the metal aluminum, lanthanum is absorbed in the intestine and accumulates in body tissues, especially in the liver, bone, muscle, kidney, and brain. Moreover, the rate of intestinal absorption of lanthanum is enhanced in chronic renal failure. Our experience with aluminum hydroxide suggests caution regarding the long-term use of another metal-based agent that displays enhanced absorption in the uremic state and progressive tissue accumulation.

Emerging drugs for hyperphosphatemia

Cardiovascular mortality is the leading cause of death in the uremic patient. Hyperphosphatemia is considered an independent risk factor associated with cardiovascular morbidity and mortality in dialysis patients. As phosphate control is not efficient with diet or dialysis, phosphate binders are commonly prescribed in patients with chronic renal failure. Aluminum salts, the first phosphate binders, even if effective, have several side effects due to their deposition in CNS, bone and hematopoietic cells. Calcium-containing phosphate binders, used in the last 15 years, increase total body calcium load and may exacerbate metastatic calcification, thus, increasing the risk of cardiovascular mortality. Recently two new compounds non-aluminum and non-calcium phosphate binders, sevelamer hydrochloride and lanthanum carbonate, have been introduced. Sevelamer, besides the effect on phosphate, has been associated with reduction of coronary and aortic calcification and with other pleiotropic effects especially on lipid metabolism. Lanthanum carbonate has similar phosphate control to calcium-based binders with less incidence of hypercalcemia but long-term clinical studies are needed for testing long-term exposure. Recently the authors found in dialysis patients, that salivary phosphorus correlated with serum phosphorus. Therefore, they supposed that the use of salivary phosphate binders could reduce its absorption and represent a chance for reducing the serum phosphate concentration in uremic patients.

Molecular modeling studies of the binding characteristics of phosphates to sevelamer hydrochloride--assessing a novel technique to reduce phosphates contamination

Recent advances in the use of polymeric materials for the remediation of phosphate from aqueous systems, including biological environments, have prompted the use of computational techniques to determine which methods are feasible to model such complex systems and to model the mechanism of binding action. In particular, Sevelamer Hydrochloride (Renagel®) is used as our model polymer. A relatively simple system is constructed with a dimer of Sevelamer Hydrochloride and four phosphate ions used for capture. This work reports on molecular dynamics and Monte Carlo simulations used to determine average structure, and points of intermolecular interaction, and calculate changes in volume after the successful capture of phosphate in our model. Our resulting volume changes are of the order of 20–25%, in comparison to experimental swelling measurements on similar systems, which have an average swelling of 50–60% in aqueous media.

Long-term comparison of sevelamer hydrochloride to calcium-containing phosphate binders

AIM

In patients with end-stage renal disease (ESRD), hyperphosphataemia and an elevated calcium-phosphorus (Ca-P) product contribute to morbidity and mortality. Suggested target goals for serum phosphorus concentration and calcium-phosphorus product have recently been lowered. As a result, long-term comparative studies of the efficacy of phosphate binders are critical. This study compares the long-term efficacy of sevelamer hydrochloride to calcium-containing binders (CCB).

METHODS

A retrospective chart review was conducted in 30 patients receiving sevelamer hydrochloride for >1 years and 25 patients receiving CCB.

RESULTS

Patients on sevelamer hydrochloride had lower serum bicarbonate concentration than those on CCB, 18.6 +/- 2.7 versus 20.3 +/- 1.8 mmol/L (P = 0.0017). Serum phosphorus concentration was higher in patients on sevelamer hydrochloride compared to CCB 2.10 +/- 0.87 versus 1.74 +/- 0.28 mmol/L (P = 0.0013), as was the Ca-P product 4.97 +/- 0.94 mmol2L2 (62.1 +/- 11.8 mg2/dL2) versus 3.97 +/- 1.18 mmol2/L2 (49.7 +/- 14.7 mg2/dL2), P = 0.0009). Only 36% of patients on sevelamer hydrochloride compared with 68% on CCB (P = 0.015) met the serum phosphorus goal of < or =1.78 mmol/L.

CONCLUSION

Patients on sevelamer hydrochloride for >1 years compared to those on CCB had a lower serum bicarbonate concentration, a higher serum phosphorus concentration and a higher Ca-P product. Clinicians should balance the increase in calcium load with CCB versus the cost and effectiveness of sevelamer hydrochloride in choosing a phosphate binder for ESRD patients.

Sevelamer therapy for pediatric end-stage renal disease

Sevelamer, a non-calcium-containing, non-aluminum-containing phosphate binder, is frequently prescribed for treatment in adults with hyperphosphatemia secondary to end-stage renal disease (ESRD). However, published information regarding sevelamer use in children younger than 11 years is lacking. We report the use of sevelamer as a phosphate binder in a 19-month-old girl with ESRD who was receiving calcium carbonate 1250 mg 3 times/day for hyperphosphatemia. The patient's initial serum phosphorus concentration was 8.6 mg/dl, and the calcium-phosphorus product was 75 mg(2)/dl(2). This was well above the level that places patients at risk for complications such as joint, vessel, and soft-tissue calcification. An aluminum-containing phosphate binder was not an option given the patient's renal disease and the concern for neurotoxicity. Sevelamer was considered, but a MEDLINE search revealed no pediatric dosing information. An initial dosage of 100 mg/kg/day divided every 8 hours was administered, as extrapolated from adult data, and then titrated to 130 mg/kg/day divided every 8 hours based on the patient's response. The child's dietary phosphorus intake remained constant throughout her hospital stay. During sevelamer therapy, her serum phosphorus concentration dropped as low as 5.2 mg/dl; at discharge it was 6.5 mg/dl, with a corresponding calcium-phosphorus product in the upper 50s. No adverse effects associated with sevelamer were observed. In the dosages we used, sevelamer resulted in an acceptable calcium-phosphorus product and returned the patient's serum phosphorus concentration to near normal. Sevelamer appears to be a viable option as a phosphate binder in children with ESRD.

The safety of phosphate binders

Disturbances of mineral metabolism occur during the early stages of chronic kidney disease. As renal function worsens, excess dietary phosphorus accumulates and blood levels increase, that can be clearly seen when the glomerular filtration rate has fallen below 30 ml/min/1.73 m2. In patients with end stage renal disease, standard dialysis (three times/week) falls far short of removing adequate amounts of absorbed phosphorus; therefore, hyperphosphataemia is found in the majority of these patients. Hyperphosphataemia has long been associated with progression of secondary hyperparathyroidism and renal osteodystrophy, it can also lead to soft-tissue and vascular calcification. Recent observational data have associated hyperphosphataemia with increased cardiovascular mortality among dialysis patients. Adequate control of serum phosphorus remains a cornerstone in the clinical management and, despite the growing amount of available therapeutic options, achievement of NFK/KDOQI targets for mineral metabolism remain poor. Several reasons may explain the failure to adequately treat hyperphosphataemia: poor compliance with diet and phosphate binder prescriptions are common causes. Also, factors related with cost, tolerance, palatability, safety and efficacy are important. In this article, the authors review the advantages and drawbacks of conventional and emerging therapies in phosphorous binding.

Novel Dosage Forms and Regimens for Sevelamer-Based Phosphate Binders

Sevelamer, a nonabsorbed, calcium- and metal-free dietary phosphate binder, consists of a polyallylamine polymer backbone with a cationic charge that shows a high capacity for binding anionically charged compounds such as phosphate. The currently licensed form of sevelamer, Renagel, exists as sevelamer hydrochloride, which disassociates in the acidic environment of the stomach and early gastrointestinal tract, exchanging the chloride ions attached to the polymer backbone for phosphate ions. The resulting absorption of these chloride ions has been reported to be accompanied by a reduction in serum levels of bicarbonate in some patients. To minimize the possibility of this effect, a new salt form of sevelamer has been developed in which carbonate replaces the chloride counter ion, thereby providing a source of buffer. The majority of phosphate binders exist only in tablet form and are dosed three times per day with meals. Genzyme has developed sevelamer carbonate in tablet form and also as a powder formulation that can be taken after mixing with water. This allows for an alternate and potentially more palatable way of dosing. Preliminary data exist suggesting that once daily dosing with sevelamer hydrochloride tablets provides similar phosphate control to three times daily dosing. By providing novel dosage forms and regimens for sevelamer-based phosphate binders, Genzyme will be providing patients and health care providers additional choices and flexibility in controlling phosphorus levels in chronic kidney disease. This should translate to increased compliance and improved rates of phosphate control.

A randomized crossover trial comparing sevelamer with calcium acetate in children with CKD

BACKGROUND

A multicenter, randomized, open-label, crossover study was performed to compare the efficacy and safety of sevelamer, a calcium-free phosphate binder, with calcium acetate in pediatric patients with chronic kidney disease (CKD).

METHODS

Children (age, 0.9 to 18 years) with CKD undergoing hemodialysis or peritoneal dialysis or with a glomerular filtration rate of 20 or greater and less than 60 mL/min/1.73 m2 (> or = 0.33 and < 1.00 mL/s/1.73 m2) were randomly assigned to the following treatment scheme: 2 weeks of washout followed by 8 weeks of treatment with either sevelamer or calcium acetate in a crossover fashion. Phosphorus, calcium, and intact parathyroid hormone in serum were measured every 2 weeks, and phosphate binder dosages were adjusted, if needed. Serum lipid and vitamin concentrations were measured at the beginning and end of each treatment period. The primary end point was the decrease in serum phosphorus levels after 8 weeks of treatment.

RESULTS

Forty-four patients were screened. Altogether, data for 18 patients (5 girls) aged 12.4 +/- 4.1 years were used for the crossover analysis. There was no significant difference in serum phosphorus levels at 8 weeks after the start of treatment in both groups. Total cholesterol (-27%) and low-density lipoprotein cholesterol (-34%) levels decreased significantly with sevelamer treatment (P < 0.02 and P < 0.005). An increased incidence of hypercalcemia (P < 0.0005) was observed with calcium acetate treatment, whereas metabolic acidosis was more frequent with sevelamer treatment (P < 0.005).

CONCLUSION

Treatment of children with CKD with sevelamer and calcium acetate provides similar phosphorus level control. The marked decrease in lipid levels and lower rate of hypercalcemia may augment the long-term benefit of sevelamer.

Increase in serum magnesium level in haemodialysis patients receiving sevelamer hydrochloride

BACKGROUND

Clinical studies have shown that sevelamer hydrochloride improves lipid profiles and attenuates the progression of the cardiovascular calcifications in haemodialysis patients. It is known that both of these properties are associated with increased magnesium levels. The effect of sevelamer on serum magnesium level is not well documented. The aim of this study was to determine the effects of sevelamer treatment on serum magnesium in haemodialysis patients and to assess the association of magnesium levels with lipid profiles and intact parathyroid hormone (iPTH).

METHODS

Phosphate binders were discontinued during a two week washout period. Forty-seven patients, whose serum phosphate was greater than 6.0 mg/dl at the end of washout, received sevelamer hydrochloride for eight weeks. The patients were then washed off sevelamer for another two weeks.

RESULTS

Mean serum phosphorus concentration declined from 7.5 +/- 1.3 to 6.4 +/- 1.2 mg/dl (P < 0.001), mean serum magnesium levels increased from 2.75 +/- 0.35 to 2.90 +/- 0.41 mg/dl (P < 0.001) and median serum iPTH levels decreased from 297 to 213 pg/ml (P=0.001) during the eight weeks of sevelamer treatment. After the two week post-treatment washout phosphorus levels increased to 7.3 +/- 1.3 mg/dl (P < 0.001), magnesium levels were reduced to 2.77 +/- 0.39 mg/dl (P < 0.001) and iPTH levels increased to 240 pg/ml (P=0.012). No change was observed in serum calcium levels during the sevelamer treatment period and the subsequent washout period. The mean decline in total and low density lipoprotein (LDL) cholesterol during sevelamer treatment was 16.3 and 28.3 (P < 0.001), respectively. The mean increase in high density lipoprotein (HDL) cholesterol and in apolipoprotein A1 was 2.9 +/- 5.8 mg/dl (P=0.004) and 6.8 +/- 11.1 mg/dl (P=0.001), respectively. Multivariate analysis showed that the rise in serum magnesium concentration significantly correlated with reductions in iPTH levels (r=-0.40, P=0.016), but did not have any significant correlation with the changes in lipid profiles.

CONCLUSIONS

Our findings indicate that patients on haemodialysis receiving sevelamer have a significant increase in serum magnesium concentrations. This increase in serum magnesium is associated with reduction in iPTH levels. The changes in lipid profiles of these patients however are not related to changes in serum magnesium levels.

Hyperphosphatemia and phosphate binders

PURPOSE

The pathophysiology of hyperphosphatemia associated with end-stage renal disease and treatment with phosphate binders are discussed.

SUMMARY

Phosphorus is an essential element necessary for the normal function of the human body, required for skeletal construction and synthesis of DNA, proteins, and adenosine triphosphate. In healthy individuals, serum phosphorus concentrations are maintained between 2.5 and 4.5 mg/dL through diet and renal excretion. In renal insufficiency, phosphorus excretion declines and hyperphosphatemia develops. The body's compensation mechanisms cause secondary hyperparathyroidism and renal osteodystrophy. Phosphate binders provide an effective means for managing serum phosphate. Commercially available phosphate binders include calcium carbonate, calcium acetate, sevelamer, lanthanum, and, rarely, aluminum hydroxide. Because of aluminum's known toxicities, aluminum-based phosphate binders have a limited place in therapy. Calcium carbonate's benefits are seen over a narrow gastric pH range, thereby limiting the drug's utility. Calcium acetate is effective over a wide pH range. Other phosphate binders, including sevelamer hydrochloride and lanthanum carbonate, have recently entered the market, but their use remains controversial.

CONCLUSION

If left untreated, hyperphosphatemia can result in secondary hyperparathyroidism, renal osteodystrophy, and metastatic calcification of blood vessels and soft tissue. The treatment of hyperphosphatemia in patients with chronic renal failure includes dialysis, dietary phosphorus restrictions, phosphate-binding medications, and vitamin D analogs. Selection of phosphate binders should be based on patient characteristics, including serum phosphate, serum calcium, and intact parathyroid hormone concentrations, and patient tolerability.

Control of Hyperphosphatemia among Patients with ESRD

Derangements of mineral metabolism occur during the early stages of chronic kidney disease (CKD). Hyperphosphatemia develops in the majority of patients with ESRD and has long been associated with progression of secondary hyperparathyroidism and renal osteodystrophy. More recent observational data have associated hyperphosphatemia with increased cardiovascular mortality among dialysis patients. Adequate control of serum phosphorus remains a cornerstone in the clinical management of patients with CKD not only to attenuate the progression of secondary hyperparathyroidism but also possibly to reduce the risk for vascular calcification and cardiovascular mortality. These measures include dietary phosphorus restriction, dialysis, and oral phosphate binders. Dietary restriction is limited in advanced stages of CKD. Phosphate binders are necessary to limit dietary absorption of phosphorus. Aluminum hydroxide is an efficient binder; however, its use has been nearly eliminated because of concerns of toxicity. Calcium salts are inexpensive and have been used effectively worldwide as an alternative to aluminum. Concerns of calcium overload have led to the investigation of alternatives. Currently, only two Food and Drug Administration-approved noncalcium, nonaluminum binders are available. Sevelamer hydrochloride is an exchange resin and was not as effective as calcium acetate in meeting new guideline recommendations in one double-blind clinical trial. Lanthanum carbonate is a rare earth element and has been studied less extensively. Concerns of long-term administration and toxicity exist. Furthermore, these agents are significantly more expensive than calcium salts, which may contribute to patient noncompliance.

Treatment of hyperphosphatemia in patients with chronic kidney disease on maintenance hemodialysis

Treatment of hyperphosphatemia in patients with chronic kidney disease on maintenance hemodialysis. Hyperphosphatemia in patients with ESRD leads to secondary hyperparathyroidism, renal osteodystrophy, and is independently associated with mortality risk. The exact mechanism by which hyperphosphatemia increases mortality risk is unknown, but it may relate to enhanced cardiovascular calcification. National Kidney Foundation K/DOQI bone metabolism and disease guidelines recommend maintenance of serum phosphorus (P) below 5.5 mg/dL, and Ca x P product less than 55 mg(2)/dL(2). Although calcium-based phosphate binders (CBPB) are cost effective, long-term safety concerns relate to their postulated role in progression of cardiovascular calcification. Sevelamer hydrochloride has been recommended as an alternative noncalcium phosphate binder. Results from the Calcium Acetate Renagel Evaluation (CARE study) indicate that calcium acetate is more effective than sevelamer in controlling serum phosphorous and Ca x P product in hemodialysis patients. In the Treat-to-Goal study, dialysis patients treated with sevelamer had slower progression of coronary and aortic calcification than patients treated with CBPB. The mechanism underlying the beneficial effect of sevelamer is unknown, but may relate to decreased calcium loading or to dramatic reductions in LDL cholesterol in sevelamer-treated patients. At present, evidence incriminating CBPB in the progression of cardiovascular calcification in ESRD remains largely circumstantial. As calcium acetate is more efficacious and cost effective than sevelamer, it remains an accepted first-line phosphate binder. In this review, we will examine these issues and provide rational guidelines for the use of calcium-based phosphate binders in patients on maintenance hemodialysis.

Complications of chronic kidney disease: anemia, mineral metabolism, and cardiovascular disease

This article focuses on the importance of three major complications of chronic kidney disease: (1) anemia, (2) calcium-phosphorus regulation and bone disease, and (3) cardiovascular risk profiling and treatment. The arguments for early and effective intervention have been amply made with respect to these three complications. Substantive trial data are sorely need to provide the definitive evidence that effective treatment of these complications results in better outcomes.

Efficacy, Tolerability, and Safety of Lanthanum Carbonate in Hyperphosphatemia: A 6-Month, Randomized, Comparative Trial versus Calcium Carbonate

BACKGROUND/AIMS

Hyperphosphatemia is an important clinical consequence of renal failure, and its multiple adverse systemic effects are associated with significantly increased risks of morbidity and mortality in dialysis patients. Existing oral phosphate binders have not permitted control of serum phosphate within currently accepted guidelines. This study compares lanthanum carbonate with calcium carbonate for control of serum phosphate in hemodialysis patients.

METHODS

In this European multicentre study, 800 patients were randomised to receive either lanthanum or calcium carbonate and the dose titrated over 5 weeks to achieve control of serum phosphate. Serum levels of phosphate, calcium and parathryoid hormone were followed over the following 20 weeks.

RESULTS

Around 65% of patients in each group achieved phosphate control, but in the calcium carbonate group this was at the expense of significant hypercalcemia (20.2% of patients vs. 0.4%). Consequently, calcium x phosphate product tended to be better controlled in the lanthanum group.

CONCLUSION

This 6-month study demonstrates that serum phosphate control with lanthanum carbonate (750-3,000 mg/day) is similar to that seen with calcium carbonate (1,500-9,000 mg/day), but with a significantly reduced incidence of hypercalcemia. Lanthanum carbonate is well tolerated and may be more effective in reducing calcium x phosphate product than calcium carbonate.

Treatment of hyperphosphatemia in patients with chronic kidney disease on maintenance hemodialysis: results of the CARE study

Most patients with end-stage renal disease develop hyperphosphatemia because their dietary intake exceeds phosphorus elimination by intermittent thrice-weekly dialysis. Inadequately treated hyperphosphatemia plays a central role in the pathogenesis of secondary hyperparathyroidism and extraosseous calcification. Moreover, in the last 15 years, this biochemical abnormality has become increasingly important following the publication of two epidemiologic studies that demonstrated an association between elevated serum phosphorus and increased mortality risk in patients with end-stage renal disease. As a result, the National Kidney Foundation Kidney Disease Outcome and Quality Initiative (K/DOQI) Bone Metabolism and Chronic Kidney Disease Guidelines recommend that serum phosphorus levels be maintained between 3.5 and 5.5 mg/dL. Unfortunately, cross-sectional studies have shown a mean serum phosphorus of 6.2 mg/dL in the maintenance hemodialysis population in the United States. An alarming 60% of patients have serum phosphorus in excess of the 5.5 mg/dL level recommended by K/DOQI guidelines. In order to achieve this new target for serum phosphorus, the most efficacious and cost-effective phosphate binders currently available should be utilized. In this review, we discuss the results of the Calcium Acetate Renagel Evaluation (CARE study), which clearly demonstrated the superiority of calcium acetate over sevelamer hydrochloride for controlling serum phosphorus and calcium-phosphate product to the levels recommended by the K/DOQI guidelines.