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Therapeutic Effects of Add-On Tenapanor for Hemodialysis Patients with Refractory Hyperphosphatemia.
Shigematsu, T, Une, Y, Ikejiri, K, Kanda, H, Fukagawa, M, Akizawa, T
American journal of nephrology. 2021;(6):496-506
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Abstract
INTRODUCTION Phosphate binders are used to treat hyperphosphatemia. Some patients have inappropriately controlled serum phosphorus levels, which may occur for many reasons, including a high pill burden and adverse events (AEs). Tenapanor selectively inhibits the passive paracellular transfer of phosphate in the gastrointestinal tract, thereby reducing serum phosphorus levels. This novel mechanism of action may contribute to improved phosphate management. The efficacy and safety of tenapanor have not been evaluated in Japanese patients with high serum phosphorus levels despite treatment with phosphate binders. This study aimed to assess the efficacy and safety of add-on tenapanor therapy for reducing serum phosphorus levels in this population. METHODS This multicenter, double-blind, randomized, placebo-controlled trial enrolled patients with refractory hyperphosphatemia undergoing hemodialysis. Patients were randomly assigned in a 1:1 ratio to receive tenapanor or placebo as an add-on to their phosphate binder regimen for 6 weeks. Change in serum phosphorus levels at week 6 (day 43) compared with the baseline value (day 1, week 0) (primary endpoint), achievement of target serum phosphorus levels (serum phosphorus level ≤6.0 or ≤5.5 mg/dL), and safety, based on all AEs and drug-related AEs, were among the outcomes evaluated. RESULTS In total, 24 patients were randomly assigned to the placebo group and 23 to the tenapanor group. The mean serum phosphorus level decreased from 7.01 mg/dL on day 1 to 6.69 mg/dL on day 43 in the placebo group and from 6.77 mg/dL on day 1 to 4.67 mg/dL on day 43 in the tenapanor group. In the placebo and tenapanor groups (modified intent-to-treat population), the mean (standard deviation) change in the serum phosphorus level at day 43 (last observation carried forward [LOCF]) was 0.08 (1.52) mg/dL and -1.99 (1.24) mg/dL, respectively, with a between-group difference of -2.07 (95% confidence interval: -2.89, -1.26; p < 0.001). The target achievement rate (serum phosphorus level ≤6.0 mg/dL at week 6 [LOCF]) was 37.5 and 87.0% in the placebo and tenapanor groups, respectively. Diarrhea was the most common drug-related AE, and it occurred in 8.3 and 65.2% of patients in the placebo and tenapanor groups, respectively. No specific AEs were observed with add-on tenapanor or with phosphate binders. DISCUSSION/CONCLUSION Therapy with existing phosphate binders and add-on tenapanor resulted in a significant decrease in serum phosphorus level compared with the placebo group in patients with refractory hyperphosphatemia despite treatment with phosphate binders. No new safety signals were raised, and add-on tenapanor was generally well tolerated.
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Molecular correlates of MRS-based 31 phosphocreatine muscle resynthesis rate in healthy adults.
Darpolor, MM, Singh, M, Covington, J, Hanet, S, Ravussin, E, Carmichael, OT
NMR in biomedicine. 2021;(1):e4402
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Dynamic phosphorus MRS (31 P-MRS) is a method used for in vivo studies of skeletal muscle energetics including measurements of phosphocreatine (PCr) resynthesis rate during recovery of submaximal exercise. However, the molecular events associated with the PCr resynthesis rate are still under debate. We assessed vastus lateralis PCr resynthesis rate from 31 P-MRS spectra collected from healthy adults as part of the CALERIE II study (caloric restriction), and assessed associations between PCr resynthesis and muscle mitochondrial signature transcripts and proteins (NAMPT, NQO1, PGC-1α, and SIRT1). Regression analysis indicated that higher concentration of nicotinamide phosphoribosyltransferase (NAMPT) protein, a mitochondrial capacity marker, was associated with faster PCr resynthesis. However, PCr resynthesis was not associated with greater physical fitness (VO2 peak) or messenger ribonucleic acid levels of mitochondrial function markers such as NQO1, PGC-1α, and SIRT1, suggesting that the impact of these molecular signatures on PCr resynthesis may be minimal in the context of an acute exercise bout. Together, these findings suggest that 31 P-MRS based PCr resynthesis may represent a valid non-invasive surrogate marker of mitochondrial NAMPT in human skeletal muscle.
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Characteristics of Patients Who Achieve Serum Phosphorus Control on Sucroferric Oxyhydroxide or Sevelamer Carbonate: A post hoc Analysis of a Phase 3 Study.
Covic, AC, Sprague, SM, Rastogi, A, Ketteler, M, Walpen, S, Perrin, A, Floege, J
Nephron. 2020;(9):428-439
Abstract
INTRODUCTION Control of hyperphosphatemia in patients on dialysis remains a major challenge. OBJECTIVE This study evaluated predictors of serum phosphorus (sP) control among dialysis patients treated with noncalcium, oral phosphate binder therapy in a phase 3 clinical trial. METHODS Post hoc analyses were performed using data for patients with hyperphosphatemia who received 52 weeks of treatment with sucroferric oxyhydroxide (SFOH) or sevelamer carbonate (sevelamer). Patients were categorized into those who achieved sP control (n = 302; defined as sP ≤ 5.5 mg/dL at week 52), and those with uncontrolled sP (n = 195; sP >5.5 mg/dL at week 52). Because SFOH and sevelamer have previously demonstrated similar effects on chronic kidney disease-mineral-bone disorder parameters in this study, the treatment groups were pooled. RESULTS Average age at baseline was higher among sP-controlled versus sP-uncontrolled patients (56.9 vs. 53.4 years; p = 0.005). Baseline sP levels were significantly lower among sP-controlled versus sP-uncontrolled patients (7.30 vs. 7.85 mg/dL; p < 0.001), and sP reductions from baseline were significantly greater in the sP-controlled group (-2.89 vs. -0.99 mg/dL at week 52; p < 0.001). Logistic regression analysis identified higher baseline sP levels (odds ratio [OR] = 0.86, 95% confidence interval [CI]: 0.765-0.960), no concomitant active vitamin D therapy use (OR = 0.51, 95% CI: 0.328-0.804), and higher body mass index at baseline (OR = 0.96, 95% CI: 0.937-0.992) as significant predictors of uncontrolled sP. CONCLUSION This analysis indicates that sP control may be more challenging in younger patients with high sP levels. Closer monitoring and management of serum phosphorus levels may be required in this population.
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Denosumab Improves Glomerular Filtration Rate in Osteoporotic Patients With Normal Kidney Function by Lowering Serum Phosphorus.
Miyaoka, D, Inaba, M, Imanishi, Y, Hayashi, N, Ohara, M, Nagata, Y, Kurajoh, M, Yamada, S, Mori, K, Emoto, M
Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research. 2019;(11):2028-2035
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Higher serum phosphorus (Pi) increases the risk for chronic kidney disease (CKD). It was reported that a single administration of denosumab or zoledronate significantly suppressed serum Pi levels as well as those of bone resorption markers in serum. Also, previous evidences suggest a link between bone anti-resorptive therapy and vasoprotective/renoprotective effects through mechanisms that remain unexplored. The aim of this study is to assess the renoprotective effect of denosumab and involvement of denosumab-induced reduction in serum Pi in osteoporotic patients. Osteoporotic patients (n = 73) without overt proteinuria in dipstick test results were treated with denosumab (60 mg) every 6 months during the study period (24 months). Estimated glomerular filtration rate based on serum cystatin C (eGFRcys) was used as a filtration marker and tartrate-resistant acid phosphatase-5b (TRACP-5b) as a bone resorption marker. For analysis of non-CKD patients (n = 56), those with eGFRcys <60 mL/min/1.73 m2 were excluded. A single injection of denosumab suppressed serum Pi as well as TRACP-5b during the first 6 months, whereas age-related decline in eGFRcys was significantly reversed, with an increase of 2.75 ± 1.2 mL/min/1.73 m2 after 24 months noted. Multivariate analysis showed that serum Pi reduction following the initial denosumab injection was positively associated with serum TRACP-5b suppression during that same period (β = 0.241, p = 0.049). In addition, a positive association of serum Pi suppression, but not of corrected calcium or TRACP-5b, with eGFRcys increase after 24 months (β = 0.321, p = 0.014) was found after adjustments for gender, age, BMI, antihypertensive drug use, albumin, and eGFRcys. The same was observed in osteoporotic cases restricted to non-CKD patients. In conclusion, serum Pi reduction resulting from phosphorus load decrement from bone induced by denosumab is a determinant for eGFRcys increase. Early introduction of bone antiresorptive therapy can retain glomerular filtration in osteoporosis cases, including non-CKD patients. © 2019 American Society for Bone and Mineral Research.
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Dynamic multivoxel-localized 31 P MRS during plantar flexion exercise with variable knee angle.
Niess, F, Fiedler, GB, Schmid, AI, Laistler, E, Frass-Kriegl, R, Wolzt, M, Moser, E, Meyerspeer, M
NMR in biomedicine. 2018;(6):e3905
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Exercise studies investigating the metabolic response of calf muscles using 31 P MRS are usually performed with a single knee angle. However, during natural movement, the distribution of workload between the main contributors to force, gastrocnemius and soleus is influenced by the knee angle. Hence, it is of interest to measure the respective metabolic response of these muscles to exercise as a function of knee angle using localized spectroscopy. Time-resolved multivoxel 31 P MRS at 7 T was performed simultaneously in gastrocnemius medialis and soleus during rest, plantar flexion exercise and recovery in 12 healthy volunteers. This experiment was conducted with four different knee angles. PCr depletions correlated negatively with knee angle in gastrocnemius medialis, decreasing from 79±14 % (extended leg) to 35±23 %(∼40°), and positively in soleus, increasing from 20±21 % to 36±25 %; differences were significant. Linear correlations were found between knee angle and end-exercise PCr depletions in gastrocnemius medialis (R2 =0.8) and soleus (R2 =0.53). PCr recovery times and end-exercise pH changes that correlated with PCr depletion were consistent with the literature in gastrocnemius medialis and differences between knee angles were significant. These effects were less pronounced in soleus and not significant for comparable PCr depletions. Maximum oxidative capacity calculated for all knee angles was in excellent agreement with the literature and showed no significant changes between different knee angles. In conclusion, these findings confirm that plantar flexion exercise with a straight leg is a suitable paradigm, when data are acquired from gastrocnemius only (using either localized MRS or small surface coils), and that activation of soleus requires the knee to be flexed. The present study comprises a systematic investigation of the effects of the knee angle on metabolic parameters, measured with dynamic multivoxel 31 P MRS during muscle exercise and recovery, and the findings should be used in future study design.
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Effect of Food Intake on the Pharmacodynamics of Tenapanor: A Phase 1 Study.
Johansson, SA, Knutsson, M, Leonsson-Zachrisson, M, Rosenbaum, DP
Clinical pharmacology in drug development. 2017;(5):457-465
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Tenapanor (RDX5791/AZD1722) is a minimally systemic small-molecule inhibitor of the sodium/hydrogen exchanger NHE3. Tenapanor acts in the gut to reduce absorption of sodium and phosphate. This phase 1 open-label, 3-way crossover study (NCT02226783) evaluated the effect of food on the pharmacodynamics of tenapanor. Eighteen volunteers completed a randomized sequence of three 4-day treatments with tenapanor hydrochloride 15 mg twice daily: before food, after food, and while fasting. Participants received a diet standardized for sodium content. Stool sodium was significantly higher with tenapanor administration before versus after food (difference, +8.8 mmol/day, P = .006) or while fasting (+11.8 mmol/day, P = .0004). Differences in urinary sodium were not significant. Stool phosphorus was not significantly different with tenapanor before versus after food and significantly higher before food versus while fasting (+4.9 mmol/day, P = .006). Urinary phosphorus was significantly lower when tenapanor was administered before (-3.9 mmol/day, P = .0005) or after food (-3.7 mmol/day, P = .0009) versus while fasting. No serious adverse events were reported. These data suggest the effect of tenapanor on sodium absorption is most pronounced when administered before meals, whereas the effect on phosphate is similar whether administered before or after meals. This may support different timings of tenapanor administration with respect to food for sodium- and phosphate-related indications.
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Efficacy and safety of sucroferric oxyhydroxide compared with sevelamer hydrochloride in Japanese haemodialysis patients with hyperphosphataemia: A randomized, open-label, multicentre, 12-week phase III study.
Koiwa, F, Yokoyama, K, Fukagawa, M, Terao, A, Akizawa, T
Nephrology (Carlton, Vic.). 2017;(4):293-300
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AIM: We aimed to investigate the non-inferiority of PA21 (sucroferric oxyhydroxide) to sevelamer hydrochloride (sevelamer) in terms of efficacy and safety in Japanese haemodialysis patients with hyperphosphataemia. METHODS In this Phase III, open-label, multicentre study, 213 haemodialysis patients with hyperphosphataemia were randomized to PA21 or sevelamer treatment for 12 weeks. The primary outcome was adjusted serum phosphorus concentration at the end of treatment; the non-inferiority of PA21 was confirmed if the upper limit of the two-sided 95% confidence interval (CI) is ≤0.32 mmol/L. Secondary outcomes were corrected serum calcium and intact-parathyroid hormone concentrations. Adverse events (AEs) and adverse drug reactions (ADRs) were evaluated. RESULTS The adjusted mean serum phosphorus concentration at the end of treatment confirmed the non-inferiority of PA21 for lowering serum phosphorus compared with sevelamer (1.62 vs 1.72 mmol/L; difference, -0.11 mmol/L; 95% CI, -0.20 to -0.02 mmol/L). The mean daily tablet intake was 5.6 ± 2.6 and 18.7 ± 7.1 tablets in the PA21 and sevelamer groups, respectively. The incidences of AEs and ADRs were not significantly different between the two groups. CONCLUSION The non-inferiority of PA21 to sevelamer was confirmed for the treatment of Japanese haemodialysis patients with hyperphosphataemia. PA21 was effective, safe, and well tolerated, while having a considerably lower pill burden than sevelamer.
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Dose-response efficacy and safety of PA21 in Japanese hemodialysis patients with hyperphosphatemia: a randomized, placebo-controlled, double-blind, Phase II study.
Koiwa, F, Terao, A
Clinical and experimental nephrology. 2017;(3):513-522
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BACKGROUND Hyperphosphatemia is common in chronic kidney disease (CKD) and associated with mortality and morbidity. We aimed to evaluate the dose-dependent efficacy and safety of PA21 (sucroferric oxyhydroxide), an iron-based phosphate binder, in Japanese hemodialysis patients with hyperphosphatemia. METHODS In this double-blind, multicenter, Phase II study, 183 patients were randomized to placebo or PA21 at doses of 250, 500, 750, or 1000 mg (based on iron content) three times/day for 6 weeks. The primary efficacy endpoint was the mean change in serum phosphorus levels from baseline to end of treatment in each group. Adverse reactions were evaluated. RESULTS The change in serum phosphorus level was significantly greater in each PA21 group than in the placebo group (analysis of covariance: P < 0.001 for all groups). A dose-dependent change in serum phosphorus levels was observed in the PA21 groups. A notable decrease in mean serum phosphorus levels to the target level of ≤6 mg/dL was shown starting at Week 1 in all PA21 groups. The cumulative achievement rates for target serum phosphorus level at the end of treatment were generally >80 % in all PA21 groups. The major adverse reaction reported was diarrhea; however, most cases were mild. CONCLUSIONS PA21 was an effective and safe treatment that decreased serum phosphorus levels starting at 1 week of treatment when administered as one 250-mg tablet three times/day. PA21 demonstrated a dose-dependent phosphorus lowering effect up to 3000 mg/day. PA21 may be a new treatment alternative with relatively low pill burden for Japanese hemodialysis patients with hyperphosphatemia.
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EPIC Trial: education programme impact on serum phosphorous control in CKD 5D patients on hemodialysis.
Martins, CTB, Biavo, BMM, Uezima, CBB, Santos, JAPD, Barros, CM, Ribeiro Júnior, E, Troconis, PC, Scavone, C, Luiz, MVSJ
Jornal brasileiro de nefrologia. 2017;(4):398-405
Abstract
INTRODUCTION In stage 5D chronic kidney disease (CKD 5D) patients, the encouragement of treatment adherence by health professionals is a significant clinical challenge. OBJECTIVES This study evaluates the impact of a nutritional education programme on hyperphosphatemia, utilizing the transtheoretical model of behavior change (TMBC). SUBJECTS AND METHODS A prospective interventional study comprising 179 CKD 5D patients with hypophosphatemia. The 4-month educational programme took place during dialysis sessions. Demographic and laboratory data were evaluated, whilst the TMBC was utilized both pre- and post-intervention. RESULTS 132 patients showed a positive change and significant reduction in phosphate levels, whilst 47 patients showed a negative change and little reduction in phosphate levels. Positive changes were identified at different levels of literacy. 117/179 participants had ongoing treatment with sevelamer throughout the trial period. 61 patients with intact parathyroid hormone (iPTH) < 300pg/ml showed phosphate level reductions, whilst 118 patients with iPTH > 300 pg/ml also showed a decrease in phosphate levels. CONCLUSIONS Nutritional education programmes can achieve excellent results when appropriately applied. An education programme may be effective across different literacy levels.
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Serum Phosphorus Concentration and Coronary Artery Calcification in Subjects without Renal Dysfunction.
Park, KS, Park, J, Choi, SH, Ann, SH, Singh, GB, Shin, ES, Lee, JS, Chung, HC
PloS one. 2016;(3):e0151007
Abstract
Serum phosphorus (P) concentration is associated with coronary artery calcification (CAC) as well as cardiovascular events in patients with chronic kidney disease. It has been suggested that this relationship is extended to subjects without renal dysfunction, but further explorations in diverse races and regions are still needed. We performed a cross-sectional study of 2,509 Korean subjects (Far Eastern Asian) with an estimated glomerular filtration rate of ≥60 ml/min/1.73 m2 and who underwent coronary computerized tomography. Serum P concentration was divided into pre-determined 4 categories: ≤3.2, 3.2< to ≤3.6, 3.6< to ≤4.0 and >4.0 mg/dL. Agatston score (AS), an index of CAC, was divided into 3 categories: 0, 0< to ≤100, and >100. A multinomial logit model (baseline outcome: AS = 0) was applied to estimate the odds ratio (OR) for each serum P category (reference: ≤3.2mg/dL). Mean age of subjects was 53.5±9.1 years and 36.9% were female. In the adjusted model, serum P concentration of 3.6< to ≤4.0 mg/dL and >4.0 mg/dL showed high ORs for AS of >100 [OR: 1.58, 95% confidence interval (CI): 1.04-2.40 and OR: 2.11, 95% CI: 1.34-3.32, respectively]. A unit (mg/dL) increase in serum P concentration was associated with 50% increase in risk of AS >100 (OR: 1.50, 95% CI: 1.16-1.94). A higher serum P concentration, even within a normal range, may be associated with a higher CAC in subjects with normal renal function.