Effect of intravenous iron sucrose on oxidative stress in peritoneal dialysis patients

AIM: Intravenous iron therapy is an accepted treatment for patients receiving hemodialysis and continuous ambulatory peritoneal dialysis (CAPD). Studies have found enhanced oxidative stress in hemodialysis patients receiving intravenous iron, but there are no clinical data for CAPD patients. The aim of the current study was to investigate the effect of 100 mg of intravenous iron-sucrose on the erythrocyte (RBC) antioxidant enzymes (namely, superoxide dismutase [SOD], catalase [CAT], and glutathione peroxidase [GSHPx]) and plasma malondialdehyde (MDA), an oxidant molecule, in CAPD patients. METHODS: Twelve CAPD patients receiving maintenance intravenous iron-sucrose were recruited. After a 12-hour fast, blood samples were taken for hemoglobin, iron, ferritin, and high-sensitivity C-reactive protein (hsCRP), and for baseline activities of erythrocyte antioxidant enzymes (i.e., SOD, CAT, GSHPx) and the plasma oxidant molecule, MDA. 100 mg iron-sucrose was infused over 30 minutes. Blood samples taken during (i.e., 15 minutes after commencement of infusion) and after (i.e., at 30 minutes, 60 minutes, and 6 hours after commencement) the infusion were taken for measurement of plasma iron, ferritin, TSAT, RBC SOD, CAT, GSHPx, and plasma MDA. RESULTS: Plasma iron and transferrin saturation elevated significantly during infusion (p < 0.05). There was no significant change in erythrocyte SOD, CAT, GSHPx, or in MDA activities. There was a reduction of GSHPx activity at the 30th minute (from 153.69 +/- 66.69 to 123.68 +/- 25.50 mU/mL), but it was not statistically significant. The patients were grouped according to baseline ferritin (100-400 and 400-800 ng/mL); 60th-minute MDA was significantly higher in the latter group (p < 0.05). There was no correlation between hsCRP and oxidant-antioxidant balance. No correlation was noted between RBC antioxidant enzymes or plasma oxidant molecule and ferritin levels. CONCLUSION: There are no acute deteriorating effects from a 100 mg of intravenous iron-sucrose in CAPD patients with optimal iron stores. This dose may be applied safely in CAPD patients.     

Efficacy and safety of sevelamer hydrochloride and calcium acetate in patients on peritoneal dialysis

Background. Inadequate phosphorus control is associated withincreased morbidity and mortality in patients with CKD stage5. Although phosphate binders are often used in patients onperitoneal dialysis (PD), no large randomized controlled studiesevaluating their use solely in this population have previouslybeen reported. Methods. In this multicentre, open-label study, adult patientson PD with serum phosphorus >5.5 mg/dl were randomized (2:1)to 12 weeks of treatment with sevelamer hydrochloride or calciumacetate. Doses were titrated to achieve serum phosphorus of3.0–5.5 mg/dl. Changes in serum phosphorus, calcium, intactparathyroid hormone (iPTH), lipids and plasma biomarkers wereassessed. Results. A total of 253 patients were screened, 143 of whomwere randomized (sevelamer hydrochloride, n = 97; calcium acetate,n = 46). Treatment groups were well balanced with regard tobaseline demographics. Serum phosphorus levels were significantlyreduced after 12 weeks with both sevelamer hydrochloride andcalcium acetate (P < 0.001). Serum PTH was also reduced inboth groups while serum calcium increased in the calcium acetategroup (P = 0.001) but not in the sevelamer hydrochloride group.Sevelamer hydrochloride was also associated with decreases intotal cholesterol, low-density lipoprotein cholesterol and uricacid and an increase in bone-specific alkaline phosphatase (allP < 0.001 versus baseline). Both treatments were well toleratedand safety profiles were consistent with previous reports inhaemodialysis patients. Hypercalcaemia was experienced by morecalcium acetate-treated patients (18 versus 2%; P = 0.001). Conclusions. In summary, sevelamer hydrochloride provides areduction in serum phosphorus compared to that obtained withcalcium-based binders in PD patients. The effects of sevelamerhydrochloride appear similar in both PD and haemodialysis populations.     

A prospective crossover trial comparing intermittent intravenous and continuous oral iron supplements in peritoneal dialysis patients.

BACKGROUND: Concomitant iron supplementation is required in the great majority of erythropoietin (Epo)-treated patients with end-stage renal failure. Intravenous (i.v.) iron supplementation has been demonstrated to be superior to oral iron therapy in Epo-treated haemodialysis patients, but comparative data in iron-replete peritoneal dialysis (PD) patients are lacking. METHODS: A 12-month, prospective, crossover trial comparing oral and i.v. iron supplementation was conducted in all Princess Alexandra Hospital PD patients who were on a stable dose of Epo, had no identifiable cause of impaired haemopoiesis other than uraemia, and had normal iron stores (transferrin saturation >20% and serum ferritin 100-500 mg/l). Patients received daily oral iron supplements (210 mg elemental iron per day) for 4 months followed by intermittent, outpatient i.v. iron infusions (200 mg every 2 months) for 4 months, followed by a further 4 months of oral iron. Haemoglobin levels and body iron stores were measured monthly. RESULTS: Twenty-eight individuals were entered into the study and 16 patients completed 12 months of follow-up. Using repeated-measures analysis of variance, haemoglobin concentrations increased significantly during the i.v. phase (108+/-3 to 114+/-3 g/l) compared with each of the oral phases (109+/-3 to 108+/-3 g/l and 114+/-3 to 107+/-4 g/l, P<0.05). Similar patterns were seen for both percentage transferrin saturation (23.8+/-2.3 to 30.8+/-3.0%, 24.8+/-2.1 to 23.8+/-2.3%, and 30.8+/-3.0 to 26.8+/-2.1%, respectively, P<0.05) and ferritin (385+/-47 to 544+/-103 mg/l, 317+/-46 to 385+/-47 mg/l, 544+/-103 to 463+/-50 mg/l, respectively, P=0.10). No significant changes in Epo dosages were observed throughout the study. I.v. iron supplementation was associated with a much lower incidence of gastrointestinal disturbances (11 vs 46%, P<0.05), but exceeded the cost of oral iron treatment by 6.5-fold. CONCLUSIONS: Two-monthly i.v. iron infusions represent a practical alternative to oral iron and can be safely administered to PD patients in an outpatient setting. Compared with daily oral therapy, 2-monthly i.v. iron supplementation in PD patients was better tolerated and resulted in superior haemoglobin levels and body iron stores.     

Efficacy and safety of monthly oral minodronate in patients with involutional osteoporosis

Summary

Monthly minodronate at 30 or 50?mg had similar efficacy as 1?mg daily in terms of change in bone mineral density (BMD) and bone turnover markers with similar safety profiles. This new regimen provides patients with a new option for taking minodronate.

Introduction

Minodronate at a daily oral dose of 1?mg has been proven to have antivertebral fracture efficacy. In the present study, the efficacy and safety of oral minodronate at monthly doses of either 30?mg or 50?mg were compared with a daily dose of 1?mg.

Methods

A total of 692 patients with involutional osteoporosis were randomized to receive minodronate at either 30 or 50?mg monthly or a daily dose of 1?mg. The primary endpoint was the percent change from baseline in lumbar spine (LS) BMD at 12?months. Total hip BMD, bone turnover markers, serum calcium (Ca), and parathyroid hormone (PTH) levels were also evaluated.

Results

Minodronate at monthly doses of 30 or 50?mg were noninferior to the 1?mg daily dose in terms of change in LS-BMD. Changes in total hip BMD were also comparable. Although a transient decrease in serum Ca and increase in PTH levels were observed in all three groups at slightly different magnitudes and time courses, changes in bone turnover markers were comparable among the different dosage groups with a similar time course. Safety profiles were also comparable.

Conclusion

Minodronate at monthly doses of 30 or 50?mg has similar efficacy to the daily 1?mg dose in terms of BMD and bone turnover markers with similar tolerability.     

Pharmacokinetics of intravenous ceftizoxime in patients on continuous ambulatory peritoneal dialysis

The pharmacokinetics of ceftizoxime (CZM) were determined in 16 non-infected CAPD patients. Patients received either 500 mg or 1000 mg CZM by i.v. bolus. The dialysate exchange volume was 2 l. Serum CZM concentrations at 10 min were 69.7 +/- 19.7 micrograms/ml (1000 mg dose) and 39.2 +/- 8.4 micrograms/ml (500 mg dose), and declined to 33.7 +/- 13.9 micrograms/ml and 16.9 +/- 3.2 micrograms/ml respectively at 360 min. Dialysate CZM levels at 10 and 360 min were 1.8 +/- 1.3 and 19.9 +/- 6.6 micrograms/ml respectively (1000 mg dose) and 1.4 +/- 0.9 and 12.6 +/- 3.5 micrograms/ml (500 mg dose). The half-time of CZM was 14.1 +/- 4.6 h. Peritoneal clearance of CZM was low and equilibrium was not achieved in 6 h. However peritoneal CZM concentrations were adequate within 1 h for the treatment of most organisms which cause CAPD-related peritonitis.     

Short-term small-dose intravenous iron trial to detect functional iron deficiency in dialysis patients

BACKGROUND/AIM: Management of renal anemia in end-stage renal disease requires careful evaluation of the iron status before and in particular during erythropoietin treatment. However, there is no simple and practical iron index accurately predictive of functional iron deficiency in these patients till now. The purpose of this prospective study, therefore, is to evaluate whether a short course of low-dose intravenous iron challenge can detect functional iron deficiency in hemodialysis patients. METHODS: Twenty-four patients with baseline serum ferritin levels between 100 and 500 ng/ml were treated with intravenous saccharated ferric oxide, 960 mg over 24 hemodialysis treatments, and the hemoglobin level was checked every week. RESULTS: Patients whose hemoglobin value increased at least by 1 g/dl within the 8-week period were classified as having functional iron deficiency or as responders (n = 26; 81.2%). All other subjects were classified as having adequate iron levels or as nonresponders (n = 6; 18.8%). There were no significant differences in age, sex, dialysis years, Kt/V, dialyzers, hemoglobin, and basal and final transferrin saturation and ferritin between responders and nonresponders. In addition, there were no iron indices with acceptable levels of sensitivity and specificity. On the contrary, the cutoff value of increments of hemoglobin of at least 0.2 g/dl after a 2-week intravenous iron trial had a sensitivity of 96.2% and a specificity of 100% in all patients (n = 32) and a sensitivity of 100% and a specificity of 100% after patients with transferrin saturation <20% were excluded (n = 24). These values had the greatest utility of the tests studied in this work. CONCLUSION: A 240-mg intravenous iron challenge during a 2-week period may be a simple, accurate, and straightforward method to detect a functional iron deficiency status in hemodialysis patients undergoing erythropoietin therapy.     

Elevated cardiac troponin T in hemodialysis patients receiving more intravenous iron sucrose

Elevated cardiac troponin T (cTnT) has been associated with shorter survival in hemodialysis patients. Moreover, intravenous (IV) iron treatment has been held responsible for oxidative stress and accelerated atherosclerosis in these patients. In the present study, we investigated the relationship between cTnT concentration, IV iron treatment, and parameters of iron status. In addition, parameters of oxidative stress, inflammation, and atherosclerosis were evaluated. Predialysis blood samples of 78 chronic hemodialysis patients were analyzed for cTnT, malondialdehyde, creatine kinase (CK), and CK-isoenzyme MB (CK-MB). In addition, the mean value of predialysis serum samples collected during the last year, were considered for homocysteine, ferritin, iron, iron binding capacity, blood cell counts, blood urea nitrogen, creatinine, albumin, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), calcium, phosphate, iPTH, cholesterol, and triglyceride. The quantity of IV iron sucrose administered during the last two years was counted from the patients' files. Echocardiography, all events related to ischemic heart disease, and urine volume were also recorded. Elevated cTnT levels (> or =0.10 ng/mL) were found in 18 patients (23.1%). The amount of iron administered was 2264+/-1871 mg with a range 0-7000 mg. Patients with elevated cTnT levels received more IV iron than those with normal cTnT (3692+/-1771 vs. 1761+/-1595 mg, p<0.001). The serum ferritin level was higher in patients with elevated cTnT (median levels; 477 vs. 288 ng/mL; P<0.05). Patients with elevated cTnT were longer on dialysis compared to those with normal levels (median times; 35.5 vs. 15 months, P<0.01) and regression analysis identified the amount of administered iron as an independent factor for elevated cTnT (P<0.01). Intravenous iron treatment and high ferritin concentration are related to high cTnT level, which has previously been incriminated as a survival marker in hemodialysis patients.     

Oxidative stress induced by iron released from transferrin in low pH peritoneal dialysis solution

Background. Transferrin binds extracellular iron and protectstissues from iron-induced oxidative stress. The binding of ironand transferrin is pH dependent and conventional peritonealdialysis (PD) solutions have unphysiologically low pH values.Herein, we investigated whether conventional PD solution releasesiron from transferrin and if the released iron causes oxidativestress. Methods. Effects of PD solutions on iron binding to transferrinwere examined with purified human transferrin and transferrinin dialysates drained from PD patients. Oxidative stress inducedby iron released from transferrin was evaluated in terms ofthe formation of thiobarbituric acid reactive substance (TBARS)and protein carbonylation in the human red blood cell (RBC)membrane. The iron deposition in peritoneal tissue from PD patientswas evaluated by Perls' staining with diaminobenzidine intensification. Results. Low pH PD solution released iron from transferrin.This iron release occurred within 1 min. Iron release was notobserved in neutralized PD solution. Iron released from transferrinin low pH PD solution increased TBARS formation and proteincarbonylation in the human RBC membrane. Iron deposition, whichis prominent in the fibrotic area facing the peritoneal cavity,was observed in the peritoneum of PD patients. Conclusions. Iron released from transferrin in low pH PD solutioncan produce oxidative stress in the peritoneum of a PD patient.Neutralizing PD solution can avoid this problem. Iron depositionin the peritoneum may participate in the pathogenesis of peritonealfibrosis in PD patients.     

Pharmacokinetics of intermittent intravenous cefazolin and tobramycin in patients treated with automated peritoneal dialysis

There is increasing use of intermittent dosing of antibiotics to treat peritoneal dialysis (PD)-related peritonitis. The disposition of intravenous cefazolin and tobramycin was studied in automated PD (APD) patients. Ten patients were recruited and received a single intravenous dose of cefazolin (15 mg/kg) and tobramycin (0.6 mg/kg). Blood and dialysate samples were collected at the beginning, middle, and end of dwells 1 to 3 (on cycler), and at the end of dwells 4 to 5 (off cycler) for a 24-h period. Baseline and 24-h urine samples were collected. Pharmacokinetic parameters were calculated using a monoexponential model. Cefazolin and tobramycin half-lives were markedly different on cycler than off cycler (cefazolin on cycler : 10.67 +/- 4.66 h; cefazolin off cycler : 23.09 +/- 5.6 h; P = 0.001; tobramycin on cycler : 14.27 +/- 4.53 h; tobramycin off cycler : 68. 5 +/- 26.47 h; P < 0.001). Mean serum and dialysate concentrations were above minimum inhibitory concentrations of susceptible organisms throughout the 24-h period for both drugs with intravenous administration. A model was developed to examine serum and dialysate concentrations after intermittent intraperitoneal administration of 15 mg/kg cefazolin and 0.6 mg/kg tobramycin. Model-predicted intraperitoneal cefazolin provides adequate serum and dialysate concentrations for 24 h. Intermittent intraperitoneal tobramycin doses must be 1.5 mg/kg for one exchange during the first day and then given as 0.5 mg/kg thereafter. It is concluded that the current empiric dosing recommendations for PD-related peritonitis may be adequate for cefazolin (15 to 20 mg/kg); however, tobramycin doses must be changed to 1.5 mg/kg intraperitoneally on day 1, then to 0.5 mg/kg intraperitoneally thereafter in APD patients.     

Correlation between iron stores and QTc dispersion in chronic ambulatory peritoneal dialysis patients

Aim: We aimed to investigate the QT dispersion and corrected QT (QTc) dispersion which are suggested as the signals of ventricular arrhythmias, in patients on maintenance CAPD and to evaluate the correlation between iron stores and these electrocardiographic parameters. Materials and method: Fifty-eight patients on maintenance CAPD and 19 healthy age- and sex-matched adults without cardiac disease were included. The PD patients were divided into two groups according to whether their computerized measurements of QTc dispersion were longer than 65?ms. Results: Although QT interval was statistically significantly shorter in control group (34?±?28 vs. 43?±?34?ms; p?<?0.05), there was no significant difference in regards to the QTc, QT dispersion and QTc dispersion between two groups. PD patients with QTc dispersion longer than 65?ms had higher levels of serum ferritin (p?=?0.038) and transferrin saturation (TSAT; p?=?0.022) than the others. QTc dispersion were positively correlated with ferritin (r?=?0.469, p?<?0.01) and TSAT (r?=?0.430, p?<?0.01) in CAPD patients. Conclusion: Although prolonged QTc, QT dispersion and QTc dispersion were suggested as the markers of ventricular arrhythmias we did not find any significant difference in regards to these parameters between control patients and CAPD patients. But the high body iron stores in these patients increase the risk of increased QT dispersion. The concern over iron overload in dialysis patients is not only because of its oxidative toxicity, but also its precipitation of arrhythmias, which may be measured by the surrogate marker of QTc dispersion.     

The therapeutic equivalence of oral and intravenous iron in renal dialysis patients.

Oral and intravenous iron were compared in patients treated with renal dialysis by a cross-over trial. Intravenous iron was given over 2 weeks as an iron dextran (equivalent to 100 mg elemental iron). Oral iron was given daily as ferrous sulphate (equivalent to 100 mg elemental iron) in a wax matrix tablet. Each treatment period lasted 26 weeks. There was no significant difference in therapeutic or unwanted effects between the treatments.     

Total dose iron infusion: safety and efficacy in predialysis patients

Iron deficiency anemia is not uncommon in predialysis patients. Oral iron often cannot maintain adequate iron stores. Hence we evaluated the safety and efficacy of total dose infusion (TDI) of iron in these patients. Anemic predialysis patients were screened and those with Hb < 7.0 g/dL and serum ferritin < 200 ng/mL were selected. Patients with active bleeding and acute liver disease were excluded. All patients were on oral iron 100 mg/day. None of the patients were on erythropoeitin. 11 patients (6 males and 5 females), aged 45.9 +/- 15 yrs, were suitable. Hb was 5.9 +/- 1.0 g/dL and serum ferritin was 89.5 + 50 ng/mL. The preparation used was iron dextran. A test dose of 25 mg in 100 mL normal saline was administered over 1 hr to all patients. One patient had fever and chills during the test dose and was not given TDI. 10 patients received TDI. None of these patients had any problem during the infusion. The dose of iron administered was 900 + 316.2 mg. One patient who received 1600 mg had arthralgia-myalgia and another patient had thrombophlebitis following TDI. One month after TDI, Hb was 8.0 + 1.0 g/dL and serum ferritin was 362 ng/mL. We feel that TDI is a safe and effective method of correcting iron deficiency in predialysis patients.     

Predictive factors of low HCO3- levels in peritoneal dialysis patients

BACKGROUND: Metabolic acidosis is a major metabolic abnormality in end-stage renal disease (ESRD) and alkali is provided with dialysis treatment to patients on chronic peritoneal dialysis (CPD) to keep their acid-base balance within normal serum HCO3- levels. METHODS AND RESULTS: We examined the levels of venous serum HCO3- in 163 patients on CPD and the predictive factors for HCO3- levels low enough to indicate metabolic acidosis. The mean value for HCO3- was 26+/-2.4 mmol/l and for anion gap was 13.1+/-3.1 mEq/l. A serum bicarbonate concentration of less than 24 mmol/l, compatible with metabolic acidosis, was observed in 13.5% of the patients. In a multivariate analysis HCO3- levels were directly correlated with older age and use of CaCO3- as phosphate binders, and inversely associated with serum potassium, the use of sevelamer and low lactate dialysis solutions. Higher serum urea levels, the use of low lactate solutions and sevelamer instead of CaCO3 were significantly predictive factors for HCO3- levels < 24 mmol/l. CONCLUSIONS: Venous HCO3- and anion gap values were within the normal ranges in stable CPD patients. In 13.5% of them, however, chronic metabolic acidosis was observed based on venous HCO3- levels < 24 mmol/l. Dietary protein intake, the use of sevelamer and low (35 mmol/l) concentration of lactate in dialysis solutions are important predictive factors for chronic metabolic acidosis in these patients.     

低蛋白饮食对腹膜透析患者氮平衡的影响

Objective To observe the influence of different dietary protein intake (DPI) on nitrogen balance and nutritional indices in peritoneal dialysis (PD) patients, and explore the minimal DPI to maintain nitrogen balance. Methods Thirty-four PD patients were randomly divided into group A, B and C with DPI as 1.2, 0.9 and 0.6 g·kg-1·d-1 respectively. All the patients admitted into our hospital and completed a 10-day assessment for nitrogen balance, as well as nutritional status including serum albumin (Alb), pre-albumin at baseline, the 7th and 10th day. Results The DPI of group A, B and C was (1.18±0.05), (0.87±0.02), (0.66±0.03) g·kg-1·d-1, whose differences were significant (P<0.01). The dietary energy intake (DEI) was 129.29 (117.57-133.89), 111.71 (100.42-133.47), 146.86 (128.03-163.18) kJ·kg-1·d-1 respectively. Nitrogen balance was positive in group A, B, C [2.99 (2.15-4.72) g, 1.20(0.59-1.89) g, 0.24 (-0.87-1.27) g]. The BUN decreased at the 7th and 10th day (P<0.01) in group C. The BUN and phosphorus in group A increased, but without significant difference as compared to baseline. No significant differences of nutritional status were found among three groups throughout the trial. Conclusion Minimal DPI 0.65 g·kg-1·d-1 plus the supplement of protein loss in dialysate can maintain the nitrogen balance in peritoneal dialysis patients.