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Background/aims: Vitamin D insufficiency and secondary hyperparathyroidism (SHPT) are associated with increased morbidity and mortality in chronic kidney disease (CKD) and are poorly addressed by current treatments. The present clinical studies evaluated extended-release (ER) calcifediol, a novel vitamin D prohormone repletion therapy designed to gradually correct low serum total 25-hydroxyvitamin D, improve SHPT control and minimize the induction of CYP24A1 and FGF23.Methods: Two identical multicenter, randomized, double-blind, placebo-controlled studies enrolled subjects from 89 US sites. A total of 429 subjects, balanced between studies, with stage 3 or 4 CKD, SHPT and vitamin D insufficiency were randomized 2:1 to receive oral ER calcifediol (30 or 60 µg) or placebo once daily at bedtime for 26 weeks. Most subjects (354 or 83%) completed dosing, and 298 (69%) entered a subsequent open-label extension study wherein ER calcifediol was administered without interruption for another 26 weeks.Results: ER calcifediol normalized serum total 25-hydroxyvitamin D concentrations (>30 ng/ml) in >95% of per-protocol subjects and reduced plasma intact parathyroid hormone (iPTH) by at least 10% in 72%. The proportion of subjects receiving ER calcifediol who achieved iPTH reductions of ≥30% increased progressively with treatment duration, reaching 22, 40 and 50% at 12, 26 and 52 weeks, respectively. iPTH lowering with ER calcifediol was independent of CKD stage and significantly greater than with placebo. ER calcifediol had inconsequential impact on serum calcium, phosphorus, FGF23 and adverse events.Conclusion: Oral ER calcifediol is safe and effective in treating SHPT and vitamin D insufficiency in CKD. [ABSTRACT FROM AUTHOR]

Background/Aims: Vitamin D insufficiency drives secondary hyperparathyroidism (SHPT) and is associated with increased cardiovascular mortality in patients with chronic kidney disease (CKD). SHPT is poorly addressed by current vitamin D repletion options. The present study evaluated a novel investigational vitamin D repletion therapy: a modified-release (MR) formulation of calcifediol designed to raise serum 25-hydroxyvitamin D in a gradual manner to minimize the induction of CYP24 and, thereby, improve the SHPT control. Methods: This randomized, double-blind, placebo-controlled trial evaluated MR calcifediol in CKD subjects (n = 78) with plasma intact parathyroid hormone (iPTH) >70 pg/ml and serum total 25-hydroxyvitamin D <30 ng/ml. Subjects received daily treatment for six weeks with oral MR calcifediol (30, 60 or 90 µg) or a placebo. Results: More than 90% of subjects treated with MR calcifediol achieved serum 25-hydroxyvitamin D levels ≥30 ng/ml versus 3% of subjects treated with placebo (p < 0.0001). Mean plasma iPTH decreased from baseline (140.3 pg/ml) by 20.9 ± 6.2% (SE), 32.8 ± 5.7 and 39.3 ± 4.3% in the 30, 60 and 90 µg dose groups, respectively, and increased 17.2 ± 7.8% in the pooled placebo group (p < 0.005). No clinically significant safety concerns arose during MR calcifediol treatment. Conclusion: Oral MR calcifediol appears safe and highly effective in treating SHPT associated with vitamin D insufficiency in CKD. © 2015 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Background/aims: Vitamin D insufficiency drives secondary hyperparathyroidism (SHPT) and is associated with increased cardiovascular mortality in patients with chronic kidney disease (CKD). SHPT is poorly addressed by current vitamin D repletion options. The present study evaluated a novel investigational vitamin D repletion therapy: a modified-release (MR) formulation of calcifediol designed to raise serum 25-hydroxyvitamin D in a gradual manner to minimize the induction of CYP24 and, thereby, improve the SHPT control.Methods: This randomized, double-blind, placebo-controlled trial evaluated MR calcifediol in CKD subjects (n = 78) with plasma intact parathyroid hormone (iPTH) >70 pg/ml and serum total 25-hydroxyvitamin D <30 ng/ml. Subjects received daily treatment for six weeks with oral MR calcifediol (30, 60 or 90 µg) or a placebo.Results: More than 90% of subjects treated with MR calcifediol achieved serum 25-hydroxyvitamin D levels ≥30 ng/ml versus 3% of subjects treated with placebo (p < 0.0001). Mean plasma iPTH decreased from baseline (140.3 pg/ml) by 20.9 ± 6.2% (SE), 32.8 ± 5.7 and 39.3 ± 4.3% in the 30, 60 and 90 µg dose groups, respectively, and increased 17.2 ± 7.8% in the pooled placebo group (p < 0.005). No clinically significant safety concerns arose during MR calcifediol treatment.Conclusion: Oral MR calcifediol appears safe and highly effective in treating SHPT associated with vitamin D insufficiency in CKD. [ABSTRACT FROM AUTHOR]

Background/Aims: Secondary hyperparathyroidism is a common complication of chronic kidney disease, resulting from inactivation of vitamin D receptor signaling and phosphate retention. Selective activation of vitamin D receptors with intravenous paricalcitol significantly reduced parathyroid hormone (PTH) levels with no significant hypercalcemia or hyperphosphatemia in predialysis and hemodialysis (HD) patients. This study investigates the effects of oral paricalcitol to reduce PTH in patients receiving chronic HD and peritoneal dialysis (PD). Methods: Eighty-eight patients were randomized in double-blind fashion to receive paricalcitol or placebo for 12 weeks. The dose of the study drug was adjusted weekly using the previous week’s intact PTH (iPTH) level as well as calcium and Ca × P product levels. The primary end points were efficacy (two consecutive iPTH decreases of ≥30%) and safety (two consecutive calcium measurements >11.0 mg/dl). Markers of biochemical bone activity were followed. Results: Demographic characteristics were similar between treatment groups. The mean paricalcitol doses (three times a week) over the entire treatment period for subjects with baseline iPTH ≤500 pg/ml and iPTH >500 pg/ml were 3.9 and 7.6 μg, respectively. A statistically significant decrease in iPTH was seen after week 1, with a mean 30% reduction occurring by week 3. A significantly greater proportion of both HD and PD paricalcitol subjects [83% (33/40) and 100% (18/18), respectively] achieved two consecutive ≥30% decreases in iPTH. The treatment groups were not statistically different in regard to the hypercalcemia safety end point. Phosphate binder use and mean serum phosphorus levels were not different between the treatment groups. The markers of bone activity improved in the treated subjects and worsened in those on placebo. Conclusion: Paricalcitol provides a rapid and sustained reduction of PTH in both HD and PD patients with minimal effect on serum calcium and phosphorus and no significant difference in adverse events as compared with placebo. Copyright © 2007 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Background: Intermittent dosing of calcitriol for secondary hyperparathyroidism (SHPT) has been associated with greater parathyroid hormone (PTH) reduction with fewer calcemic and phosphatemic effects than daily (QD) dosing. Methods: Secondary analyses of three randomized, double-blind, placebo-controlled multicenter studies in stage 3 and 4 chronic kidney disease (CKD) patients with SHPT were performed to compare three times per week (TIW) with QD dosing of paricalcitol. The pharmacokinetics of TIW and QD dosing of paricalcitol capsules were assessed in a separate group of healthy subjects. Results: Pharmacokinetics revealed similar steady state paricalcitol exposure between dosing regimens. In CKD patients, baseline data were similar between the TIW studies (n = 72, paricalcitol; n = 73, placebo) and QD studies (n = 35, paricalcitol; n = 40, placebo). Both dosing regimens resulted in similar efficacy (91%) for the primary end point of two consecutive ≥30% decreases in intact PTH from baseline, but the QD regimen resulted in a greater percent reduction in intact PTH from baseline. The chances for developing increased serum calcium and phosphorus levels or Ca × P product were similar between paricalcitol and placebo groups for both treatment regimens. Furthermore, no difference in the risk for these elevations was detected between the TIW and QD regimens. Conclusions: QD dosing of paricalcitol capsules is as efficacious as TIW dosing in achieving the primary end point (2 consecutive ≥30% reductions in PTH) in stage 3 and 4 CKD patients with SHPT. Moreover, the QD regimen had no significant effect on hypercalcemia, hyperphosphatemia or Ca × P product as compared with placebo or intermittent dosing. Copyright © 2006 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Background: Although hypercalciuria has the same prevalence in children as adults, children rarely develop renal stones. This may be explained by a greater urinary citrate excretion in infants compared with adults. The present study examines the renal excretion of citrate and renal cortical citrate metabolism in infant and adult rats.Methods: Adult male and newly weaned infant rats were acclimated to metabolic cages and fed synthetic diets. Urine was collected after two days, and renal cortical citrate metabolism was assayed.Results: Infant rats had a lower plasma [HCO3-] and higher plasma [K+] and had a fourfold higher urinary citrate:creatinine ratio and a twofold higher concentration of citrate in their urine compared with adult rats. This higher urinary citrate excretion was not due to a difference in renal proximal tubular Na/citrate cotransporter activity, nor renal cortical citrate synthase or ATP citrate lyase activities in infants as compared with adults. However, infant rat kidneys had significantly lower mitochondrial aconitase (m-aconitase) activity. Renal cortical citrate concentrations were comparable in infant and adult rats. Manipulation of plasma [K+] to adult levels did not affect the higher urinary citrate excretion in infant rats.Conclusions: Urinary citrate excretion in infant rats is greater than in adults but does not parallel tissue [citrate]. Thus, this higher urinary citrate is likely due to maturational differences in the proximal tubule, other than Na/citrate cotransport, that directly affect citrate transport. [ABSTRACT FROM AUTHOR]

Background: Short-term treatment for people with type 2 diabetes using a low dose of the selective endothelin A receptor antagonist atrasentan reduces albuminuria without causing significant sodium retention. We report the long-term effects of treatment with atrasentan on major renal outcomes.Methods: We did this double-blind, randomised, placebo-controlled trial at 689 sites in 41 countries. We enrolled adults aged 18-85 years with type 2 diabetes, estimated glomerular filtration rate (eGFR) 25-75 mL/min per 1·73 m2 of body surface area, and a urine albumin-to-creatinine ratio (UACR) of 300-5000 mg/g who had received maximum labelled or tolerated renin-angiotensin system inhibition for at least 4 weeks. Participants were given atrasentan 0·75 mg orally daily during an enrichment period before random group assignment. Those with a UACR decrease of at least 30% with no substantial fluid retention during the enrichment period (responders) were included in the double-blind treatment period. Responders were randomly assigned to receive either atrasentan 0·75 mg orally daily or placebo. All patients and investigators were masked to treatment assignment. The primary endpoint was a composite of doubling of serum creatinine (sustained for ≥30 days) or end-stage kidney disease (eGFR <15 mL/min per 1·73 m2 sustained for ≥90 days, chronic dialysis for ≥90 days, kidney transplantation, or death from kidney failure) in the intention-to-treat population of all responders. Safety was assessed in all patients who received at least one dose of their assigned study treatment. The study is registered with ClinicalTrials.gov, number NCT01858532.Findings: Between May 17, 2013, and July 13, 2017, 11 087 patients were screened; 5117 entered the enrichment period, and 4711 completed the enrichment period. Of these, 2648 patients were responders and were randomly assigned to the atrasentan group (n=1325) or placebo group (n=1323). Median follow-up was 2·2 years (IQR 1·4-2·9). 79 (6·0%) of 1325 patients in the atrasentan group and 105 (7·9%) of 1323 in the placebo group had a primary composite renal endpoint event (hazard ratio [HR] 0·65 [95% CI 0·49-0·88]; p=0·0047). Fluid retention and anaemia adverse events, which have been previously attributed to endothelin receptor antagonists, were more frequent in the atrasentan group than in the placebo group. Hospital admission for heart failure occurred in 47 (3·5%) of 1325 patients in the atrasentan group and 34 (2·6%) of 1323 patients in the placebo group (HR 1·33 [95% CI 0·85-2·07]; p=0·208). 58 (4·4%) patients in the atrasentan group and 52 (3·9%) in the placebo group died (HR 1·09 [95% CI 0·75-1·59]; p=0·65).Interpretation: Atrasentan reduced the risk of renal events in patients with diabetes and chronic kidney disease who were selected to optimise efficacy and safety. These data support a potential role for selective endothelin receptor antagonists in protecting renal function in patients with type 2 diabetes at high risk of developing end-stage kidney disease.Funding: AbbVie. [ABSTRACT FROM AUTHOR]