Iron sucrose and ferric carboxymaltose: no correlation between physicochemical stability and biological activity.

Intravenous iron preparations, like iron sucrose (IS) and ferric carboxymaltose (FCM) differ in their physicochemical stability. Thus differences in storage and utilization can be expected and were investigated in a non-clinical study in liver parenchyma HepG2-cells and THP-1 macrophages as models for toxicological and pharmacological target cells. HepG2-cells incorporated significant amounts of IS, elevated the labile iron pool (LIP) and ferritin and stimulated iron release. HepG2-cells had lower basal cellular iron and ferritin content than THP-1 macrophages, which showed only marginal accumulation of IS and FCM. However, FCM increased the LIP up to twofold and significantly elevated ferritin within 24 h in HepG2-cells. IS and FCM were non-toxic for HepG2-cells and THP-1 macrophages were more sensitive to FCM compared to IS at all concentrations tested. In a cell-free environment redox-active iron was higher with IS than FCM. Biostability testing via assessment of direct transfer to serum transferrin did not reflect the chemical stability of the complexes (i.e., FCM > IS). Effect of vitamin C on mobilisation to transferrin was an increase with IS and interestingly a decrease with FCM. In conclusion, FCM has low bioavailability for liver parenchyma cells, therefore liver iron deposition is unlikely. Ascorbic acid reduces transferrin-chelatable iron from ferric carboxymaltose, thus effects on hepcidin expression should be investigated in clinical studies.

Bioavailability and stability of intravenous iron sucrose originator versus generic iron sucrose AZAD.

CONTEXT: Severe iron deficiency requires intravenous iron supplementation to replenish iron stores. Intravenous iron sucrose has been used for decades for the treatment of anemia. New generic iron sucrose products are now marketed for the use in several countries and there is an ongoing discussion about the safety and efficacy of iron sucrose similars. OBJECTIVE: In this study, we compared the iron sucrose originator Venofer® and the generic iron sucrose AZAD (ISA) regarding bioavailability, toxicity and stability in human THP-1 cells and HepG2 cells. METHODS: The bioavailability of Venofer® and ISA was investigated in both cell types by a ferrozin-based assay. The release of incorporated iron was assayed by atomic absorption spectroscopy. Ferritin content was measured by enzyme-linked immunosorbent assay (ELISA). HepG2 cells were used to investigate the intracellular labile iron pool (LIP), which was measured by the fluorescent calcein assay. The amount of redox-active iron within the iron formulations was assayed using fluorescent dichlorofluorescein. RESULTS: We found no significant differences in all parameters between Venofer® and ISA in regard of bioavailability, toxicity and stability in vitro. DISCUSSION: ISA shows identical physico-chemical features and identical bioavailability in vitro. This study is a profound basis for future clinical tests with generic iron sucrose compounds.

Correlation of frataxin content in blood and skeletal muscle endorses frataxin as a biomarker in Friedreich ataxia.

BACKGROUND: Friedreich ataxia is an autosomal recessive disorder caused by mutations in the frataxin gene, leading to reduced levels of the mitochondrial protein frataxin. Assays to quantitatively measure frataxin in peripheral blood have been established. To determine the validity of frataxin as a biomarker for clinical trials, we assessed frataxin in clinically affected tissue. METHODS: In 7 patients with Friedreich ataxia, frataxin content was measured in blood and skeletal muscle before and after treatment with recombinant human erythropoietin, applying the electrochemiluminescence immunoassay. RESULTS: We found frataxin content to be correlated in peripheral blood mononuclear cells and skeletal muscle in drug-naive patients with Friedreich ataxia. The correlation of frataxin content in both compartments remained significant after 8 weeks of treatment. Skeletal-muscle frataxin values correlated with ataxia using the Scale for the Assessment and Rating of Ataxia score. CONCLUSIONS: Our results endorse frataxin measurements in peripheral blood cells as a valid biomarker in Friedreich ataxia.

Effects of erythropoietin on frataxin levels and mitochondrial function in Friedreich ataxia--a dose-response trial.

Friedreich ataxia (FRDA) is an autosomal recessive inherited neurodegenerative disorder leading to reduced expression of the mitochondrial protein frataxin. Previous studies showed frataxin upregulation in FRDA following treatment with recombinant human erythropoietin (rhuEPO). Dose-response interactions between frataxin and rhuEPO have not been studied until to date. We administered escalating rhuEPO single doses (5,000, 10,000 and 30,000 IU) in monthly intervals to five adult FRDA patients. Measurements of frataxin, serum erythropoietin levels, iron metabolism and mitochondrial function were carried out. Clinical outcome was assessed using the "Scale for the assessment and rating of ataxia". We found maximal erythropoietin serum concentrations 24 h after rhuEPO application which is comparable to healthy subjects. Frataxin levels increased significantly over 3 months, while ataxia rating did not reveal clinical improvement. All FRDA patients had considerable ferritin decrease. NADH/NAD ratio, an indicator of mitochondrial function, increased following rhuEPO treatment. In addition to frataxin upregulation in response to continuous low-dose rhuEPO application shown in previous studies, our results indicate for a long-lasting frataxin increase after single high-dose rhuEPO administration. To detect frataxin-derived neuroprotective effects resulting in clinically relevant improvement, well-designed studies with extended time frame are required.

Variations of frataxin protein levels in normal individuals.

Friedreich's ataxia (FRDA) is the most common of the inherited ataxias and is associated with GAA trinucleotide repeat expansions within the first intron of the frataxin (FXN) gene. There are expanded FXN alleles from 66 to 1,700 GAA·TTC repeats in FRDA patients and correlations between number of GAA repeats and frataxin protein levels are assumed. Here, we present for the first time frataxin protein levels as well as analysis of GAA triplet repeats in the FXN gene in a population of 50 healthy Austrian people. Frataxin protein levels were measured in lymphocytes from blood samples by ELISA and GAA repeats were analyzed by capillary electrophoresis. Rather unexpectedly, we found a high variation of frataxin protein levels among the individuals. In addition, there was no correlation between frataxin levels, GAA repeats, age and sex in this group. However, these findings are of great importance for better characterization of the disease.

Carbamylated erythropoietin increases frataxin independent from the erythropoietin receptor.

BACKGROUND: Friedreich's ataxia (FRDA) is a neurodegenerative disorder caused by decreased expression of the mitochondrial protein frataxin. Recently we showed in a clinical pilot study in Friedreich's ataxia patients that recombinant human erythropoietin (rhuEPO) significantly increases frataxin-expression. In this in vitro study, we investigated the role of the erythropoietin receptor (EPO-R) in the frataxin increasing effect of rhuEPO and if nonerythropoietic carbamylated erythropoietin (CEPO), which cannot bind to the classical EPO-R increases frataxin expression. MATERIALS AND METHODS: In our experiments human erythroleukaemic K562 cells (+ EPO-R), human monocytic leukemia THP-1 cells (- EPO-R) and isolated primary lymphocytes from healthy control and FRDA patients were incubated with different concentrations of rhuEPO or CEPO. Frataxin-expression was detected by an electrochemical luminescence immunoassay (based on the principle of an ELISA). RESULTS: We show that rhuEPO increases frataxin-expression in K562 cells (expressing EPO-R) as well as in THP-1 cells (without EPO-R expression). These results were confirmed by the finding that CEPO, which cannot bind to the classical EPO-R increased frataxin expression in the same concentration range as rhuEPO. In addition, we show that both EPO derivatives significantly increase frataxin-expression in vitro in control and Friedreich's ataxia patients primary lymphocytes. CONCLUSION: Our results provide a scientific basis for further studies examining the effectiveness of nonerythropoietic derivatives of erythropoietin for the treatment of Friedreich's ataxia patients.

Friedreich's ataxia: clinical pilot trial with recombinant human erythropoietin.

To determine the role of recombinant human erythropoietin as a possible treatment option in Friedreich's ataxia, we performed an open-label clinical pilot study. Primary outcome measure was the change of frataxin levels at week 8 versus baseline. Twelve Friedreich's ataxia patients received 5,000 units recombinant human erythropoietin three times weekly subcutaneously. Frataxin levels were measured in isolated lymphocytes by enzyme-linked immunosorbent assay. In addition, urinary 8-hydroxydeoxyguanosine and serum peroxides, were measured. Treatment with recombinant human erythropoietin showed a persistent and significant increase in frataxin levels after 8 weeks (p < 0.01). All patients showed a reduction of oxidative stress markers.

Neurological effects of recombinant human erythropoietin in Friedreich's ataxia: a clinical pilot trial.

In a "proof-of-concept" study, we demonstrated that recombinant human erythropoietin (rhuEPO) increases frataxin levels in Friedreich's ataxia (FRDA) patients. We now report a 6-month open-label clinical pilot study of safety and efficacy of rhuEPO treatment in FRDA. Eight adult FRDA patients received 2.000 IU rhuEPO thrice a week subcutaneously. Clinical outcome measures included Ataxia Rating Scales. Frataxin levels and indicators for oxidative stress were assessed. Hematological parameters were monitored biweekly. Scores in Ataxia Rating Scales such as FARS (P = 0.0063) and SARA (P = 0.0045) improved significantly. Frataxin levels increased (P = 0.017) while indicators of oxidative stress such as urine 8-OHdG (P = 0.012) and peroxide levels decreased (P = 0.028). Increases in hematocrit requiring phlebotomies occurred in 4 of 8 patients. In this explorative open-label clinical pilot study, we found an evidence for clinical improvement together with a persistent increase of frataxin levels and a reduction of oxidative stress parameters in patients with FRDA receiving chronic treatment with rhuEPO. Safety monitoring with regular blood cell counts and parameters of iron metabolism is a potential limitation of this approach.

Hydrogen sulphide: a novel physiological inhibitor of LDL atherogenic modification by HOCl.

Hypochlorite (HOCl), the product of the activated myeloperoxidase/H(2)O(2)/chloride (MPO/H(2)O(2)/Cl(- )) system is favored as a trigger of LDL modifications, which may play a pivotal role in early atherogenesis. As HOCl has been shown to react with thiol-containing compounds like glutathione and N-acetylcysteine protecting LDL from HOCl modification, we have tested the ability of hydrogen sulfide (H(2)S) - which has recently been identified as an endogenous vasorelaxant - to counteract the action of HOCl on LDL. The results show that H(2)S could inhibit the atherogenic modification of LDL induced by HOCl, as measured by apolipoprotein alterations. Beside its HOCl scavenging potential, H(2)S was found to inhibit MPO (one may speculate that this occurs via H(2)S/heme interaction) and destroy H(2)O(2). Thus, H(2)S may interfere with the reactants and reaction products of the activated MPO/H(2)O(2)/Cl(- ) system. Our data add to the evidence of an anti-atherosclerotic action of this gasotransmitter taking the role of HOCl in the atherogenic modification of LDL into account.

No changes in heme synthesis in human Friedreich´s ataxia erythroid progenitor cells.

Friedreich's ataxia (FRDA) is a neurodegenerative disease caused by reduced expression of the protein frataxin. Frataxin is thought to play a role in iron-sulfur cluster biogenesis and heme synthesis. In this study, we used erythroid progenitor stem cells obtained from FRDA patients and healthy donors to investigate the putative role, if any, of frataxin deficiency in heme synthesis. We used electrochemiluminescence and qRT-PCR for frataxin protein and mRNA quantification. We used atomic absorption spectrophotometry for iron levels and a photometric assay for hemoglobin levels. Protoporphyrin IX and Ferrochelatase were analyzed using auto-fluorescence. An "IronChip" microarray analysis followed by a protein-protein interaction analysis was performed. FRDA patient cells showed no significant changes in iron levels, hemoglobin synthesis, protoporphyrin IX levels, and ferrochelatase activity. Microarray analysis presented 11 genes that were significantly changed in all patients compared to controls. The genes are especially involved in oxidative stress, iron homeostasis and angiogenesis. The mystery about the involvement of frataxin on iron metabolism raises the question why frataxin deficiency in primary FRDA cells did not lead to changes in biochemical parameters of heme synthesis. It seems that alternative pathways can circumvent the impact of frataxin deficiency on heme synthesis. We show for the first time in primary FRDA patient cells that reduced frataxin levels are still sufficient for heme synthesis and possibly other mechanisms can overcome reduced frataxin levels in this process. Our data strongly support the fact that so far no anemia in FRDA patients was reported.

Differential response of iron metabolism to oxidative stress generated by antimycin A and nitrofurantoin.

The close interrelationship of oxidative stress and iron is evident by the influence of intracellular reactive oxygen species on iron metabolism. Oxygen radicals can lead to release of iron from iron-sulfur proteins and ferritin, and can damage iron-containing enzymes such as mitochondrial aconitase. Treatment of HepG2 human hepatoma cells with antimycin A has two effects relating to iron depending on the concentrations of antimycin A: increase of the labile iron pool and stimulation of non-transferrin-bound iron uptake. Whereas the first could also be generated with nitrofurantoin, the stimulation of non-transferrin-bound iron uptake was only seen with antimycin A and needed considerably higher concentrations. Pretreatment of the cells with ebselen, which scavenges peroxides, reverted only the effect of nitrofurantoin on the labile iron pool. Depletion with iron chelators before or after treatment with antimycin A diminished the stimulation of non-transferrin-bound iron uptake. We conclude that the generation of oxygen radicals in the mitochondria leads to the liberation of iron from mitochondrial enzymes, which enters the labile iron pool. But high concentrations of antimycin A leading to the stimulation of non-transferrin-bound iron uptake is possibly not related to the inhibition of the respiratory chain.

Sulfite facilitates LDL lipid oxidation by transition metal ions: a pro-oxidant in wine?

Lipid oxidation in LDL may play a role in atherogenesis. It has been shown that sulfite - a compound in the aqueous fraction of wine - could inhibit free radical (AAPH) mediated oxidation of plasma. Thus, sulfite has been proposed as an antioxidant. In contrast, the aqueous phase of wine has recently been shown to contain not fully identified compounds promoting transition metal ion (Cu(2+)) initiated LDL oxidation. As transition metal ions can catalyse the auto-oxidation of sulfite, we studied the influence of sulfite on Cu(2+) initiated LDL oxidation. The results show that sulfite at concentrations found in vivo strongly facilitated LDL oxidation by Cu(2+). The LDL-oxidase activity of ceruloplasmin was also stimulated by sulfite. ROS formation by Cu(2+)/SO(3)(2-) was not inhibited by SOD but by catalase. We propose that formation of Cu(+), sulfite radicals (SO(3)*(-)) and hydroxyl radicals (OH(*)) is a mechanism by which sulfite could act as a pro-atherogenic agent in presence of transition metal ions.

Aluminum ions stimulate the oxidizability of low density lipoprotein by Fe2+: implication in hemodialysis mediated atherogenic LDL modification.

OBJECTIVE: Al(3+) stimulates Fe(2+) induced lipid oxidation in liposomal and cellular systems. Low-density lipoprotein (LDL) oxidation may render the particle atherogenic. As elevated levels of Al(3+) and increased lipid oxidation of LDL are found in sera of hemodialysis patients, we investigated the influence of Al(3+) on LDL oxidation. MATERIALS AND METHODS: Using different LDL modifying systems (Fe(2+), Cu(2+), free radical generating compounds, human endothelial cells, hemin/H(2)O(2) and HOCl), the influence of Al(3+) on LDL lipid and apoprotein alteration was investigated by altered electrophoretic mobility, lipid hydroperoxide-, conjugated diene- and TBARS formation. RESULTS: Al(3+) could stimulate the oxidizability of LDL by Fe(2+), but not in the other systems tested. Al(3+) and Fe(2+) were found to bind to LDL and Al(3+)could compete with Fe(2+) binding to the lipoprotein. Fluorescence polarization data indicated that Al(3+) does not affect the phospholipid compartment of LDL. CONCLUSIONS: The results indicate that increased LDL oxidation by Fe(2+) in presence of Al(3+) might be due to blockage of Fe(2+) binding sites on LDL making more free Fe(2+) available for lipid oxidation.

An open-label trial in Friedreich ataxia suggests clinical benefit with high-dose resveratrol, without effect on frataxin levels.

Friedreich ataxia (FRDA) is due to a triplet repeat expansion in FXN, resulting in deficiency of the mitochondrial protein frataxin. Resveratrol is a naturally occurring polyphenol, identified to increase frataxin expression in cellular and mouse models of FRDA and has anti-oxidant properties. This open-label, non-randomized trial evaluated the effect of two different doses of resveratrol on peripheral blood mononuclear cell (PBMC) frataxin levels over a 12-week period in individuals with FRDA. Secondary outcome measures included PMBC FXN mRNA, oxidative stress markers, and clinical measures of disease severity. Safety and tolerability were studied. Twenty-four participants completed the study; 12 received low-dose resveratrol (1 g daily) and 12 high-dose resveratrol (5 g daily). PBMC frataxin levels did not change in either dosage group [low-dose group change: 0.08 pg/µg protein (95% CI -0.05, 0.21, p = 0.21); high-dose group change: 0.03 pg/µg protein (95% CI -0.10, 0.15, p = 0.62)]. Improvement in neurologic function was evident in the high-dose group [change in Friedreich Ataxia Rating Scale -3.4 points, 95% CI (-6.6, -0.3), p = 0.036], but not the low-dose group. Significant improvements in audiologic and speech measures, and in the oxidative stress marker plasma F2-isoprostane were demonstrated in the high-dose group only. There were no improvements in cardiac measures or patient-reported outcome measures. No serious adverse events were recorded. Gastrointestinal side-effects were a common, dose-related adverse event. This open-label study shows no effect of resveratrol on frataxin levels in FRDA, but suggests that independent positive clinical and biologic effects of high-dose resveratrol may exist. Further assessment of efficacy is warranted in a randomized placebo-controlled trial.

Influence of parenteral iron preparations on non-transferrin bound iron uptake, the iron regulatory protein and the expression of ferritin and the divalent metal transporter DMT-1 in HepG2 human hepatoma cells.

It is widely assumed that standard parenteral iron preparations are degraded in the reticuloendothelial cells and that the iron is subsequently incorporated into transferrin. Hepatocytes or other epithelial cells have been considered as not affected. We show that this picture should be carefully reconsidered. By using the human hepatoma cell line HepG2 we showed that the parenteral iron preparations ferric saccharate and ferric gluconate donated iron to the cells as efficiently as low molecular weight iron and stimulated non-transferrin bound iron uptake. This led to inactivation of the iron regulatory protein 1 and to an increase in the expression of ferritin and of the divalent metal transporter (DMT-1). Ferric dextran was only a weak stimulator of ferritin and DMT-1 expression. The observed changes in iron metabolism occurred at concentrations of parenteral iron that can also be found in the plasma of patients after i.v. infusion. We conclude that parenteral iron also influences the iron metabolism of non-reticuloendothelial cells like HepG2 cells. Further the increase in the expression of the transporter DMT-1 in HepG2 cells after iron treatment is in contrast to the regulation in the duodenum and may be involved in the upregulated uptake of potentially toxic non-transferrin bound iron from the circulation to store it in the non-toxic form of ferritin.

White matter changes in patients with friedreich ataxia after treatment with erythropoietin.

BACKGROUND AND PURPOSE: Erythropoietin (EPO) has received growing attention because of its neuroregenerative properties. Preclinical and clinical evidence supports its therapeutic potential in brain conditions like stroke, multiple sclerosis, and schizophrenia. Also, in Friedreich ataxia, clinical improvement after EPO therapy was shown. The aim of this study was to assess possible therapy-associated brain white matter changes in these patients. METHODS: Nine patients with Friedreich ataxia underwent Diffusion Tensor Imaging (DTI) before and after EPO treatment. Tract-based spatial statistics was used for longitudinal comparison. RESULTS: We detected widespread longitudinal increase in fractional anisotropy and axial diffusivity (D||) in cerebral hemispheres bilaterally (P < .05, corrected), while no changes were observed within the cerebellum, medulla oblongata, and pons. CONCLUSIONS: To the best of our knowledge, this is the first DTI study to investigate the effects of EPO in a neurodegenerative disease. Anatomically, the diffusivity changes appear disease unspecific, and their biological underpinnings deserve further study.

A high throughput electrochemiluminescence assay for the quantification of frataxin protein levels.

Friedreich's ataxia (FRDA) is an autosomal recessive neurodegenerative disease affecting 1 in 50,000 people and is caused by a GAA-trinucleotide expansion in the frataxin gene located on chromosome locus 9q13 which results in a markedly reduced expression of frataxin, a small mitochondrial protein. The exact function of frataxin is still unknown and currently there is no approved treatment available. In the near future there will be a high demand for measuring frataxin protein levels due to the development of therapeutic strategies for FRDA based on manipulating frataxin expression levels in vivo. In this paper we describe the development of an electrochemiluminescence assay (ECLIA) to measure frataxin protein levels in a 96-well plate format. The ECLIA for frataxin is able to measure human and mouse samples and is highly quantitative, accurate and reproducible, with low intra- and inter-assay error throughout a wide working range. The assay has an excellent precision and provides a new tool for the set up of high-throughput screening for basic research and for clinical studies with FRDA patients.

In vitro study on the effects of iron sucrose, ferric gluconate and iron dextran on redox-active iron and oxidative stress.

Concerns exist that administration of intravenous (i.v.) iron preparations is associated with oxidative stress. Therefore iron sucrose (CAS 8047-67-4), ferric gluconate (CAS 34098-81-1) and iron dextran (CAS 9004-66-4) were assessed for redox-active iron by a dichlorofluorescein assay and for intracellular reactive oxygen species (ROS) generation and cytotoxicity in HepG2 cells. Examining each i.v. iron preparation at its maximum concentration achieved following clinically frequently used doses in a 70 kg individual in in vitro experiments, redox-active iron was highest with ferric gluconate, followed by iron dextran and iron sucrose. Interestingly, when the i.v. iron preparations were diluted in human serum instead of buffer, redox-active iron was highest with iron dextran, followed by iron sucrose, and practically disappeared with ferric gluconate. ROS production in HepG2 cells was increased by all i.v. iron preparations. However, in the neutral red cytotoxicity assay all i.v. iron preparations were non-toxic. In conclusion, ferric gluconate showed the highest increase in intracellular ROS-production in HepG2 cells and the highest amount of redox-active iron in buffer in the in vitro assays. In contrast to the other i.v. iron preparations, redox-active iron from ferric gluconate was rendered completely redox-inactive by serum, indicating that redox-active iron in the various preparations has different chemical properties.

Iron availability and complex stability of iron hydroxyethyl starch and iron dextran a comparative in vitro study with liver cells and macrophages.

BACKGROUND: Intravenous iron (IVI) therapy is required in patients with end-stage renal disease (ESRD) under chronic haemodialysis (HD). In this in vitro study we investigated the availability and stability of iron hydroxyethyl starch (iron-Hes) compounds in THP-1 cells (macrophage phenotype) and liver cells (HepG2 cells) and compared it with the well-known iron dextran. METHODS: The uptake and release of these iron formulations by THP-1 cells (macrophage phenotype) and HepG2 cells were investigated with atomic absorption spectrometry (AAS). Ferritin was measured by ELISA. HepG2 cells were used to investigate effects of IVI on the intracellular labile iron pool (LIP), which was measured by using the fluorescent calcein assay. The amount of redox-active iron within the iron formulations was assayed using dichlorofluorescein as fluorescent probe. RESULTS: All iron preparations were taken up, stored in ferritin and released again by macrophages and HepG2-cells. This study shows that the availability and stability of iron-HES formulations in vitro are comparable with the well-known iron dextran compounds. CONCLUSIONS: Our results indicate that these new iron formulations have a good stability and availability in vitro and are comparable with the well-known iron dextran complexes.

Intravenous iron preparations and ascorbic acid: effects on chelatable and bioavailable iron.

BACKGROUND: There is growing interest to use ascorbic acid as adjuvant therapy for patients with recombinant human erythropoietin-hyporesponsiveness (rHuEpo). Several clinical studies showed the beneficial effect of ascorbic acid treatment on hematologic parameters in rHuEpo-treated hemodialysis patients with elevated or even normal iron stores. However, whether ascorbic acid directly affects stability and cellular metabolism of intravenous iron preparations (IVI) is not well understood. METHODS: The preparations for testing were iron sucrose (Venofer), ferric gluconate (Ferrlecit), and iron dextran (INFeD). HepG2-cells were used to investigate effects of ascorbic acid on iron bioavailability for the intracellular labile iron pool (LIP) from IVI by using the fluorescent calcein-assay, and cellular ferritin content was measured by enzyme-linked immunosorbent assay (ELISA). Transferrin-chelatable iron was assessed by fluorescent-apotransferrin, and cell toxicity was assayed by neutral red cytotoxicity test. RESULTS: The effects of vitamin C on different preparations do not reflect their known chemical stability (i.e., iron dextran >iron sucrose >ferric gluconate). Effects of ascorbic acid on the increase of the intracellular LIP, as well as on increasing mobilization to transferrin in serum, were limited to iron sucrose. Ascorbic acid did not increase cell toxicity and the amount of low molecular weight iron in serum. CONCLUSION: We conclude that corrected ascorbic acid levels in hemodialysis (HD) patients could increase the amount of bioavailable iron from iron sucrose, but not from other classes of IVI. Vitamin C administration could therefore result in a lower need of iron sucrose to correct anemia.