Ferrous versus ferric oral iron formulations for the treatment of iron deficiency: a clinical overview

Iron therapy in anaemic adults without chronic kidney disease

BACKGROUND

Anaemia affects about a quarter of the world's population. An estimated 50% of anaemic people have anaemia due to iron deficiency.

OBJECTIVES

To assess the safety and efficacy of iron therapies for the treatment of adults with anaemia who are not pregnant or lactating and do not have chronic kidney disease.

SEARCH METHODS

We ran the search on 11 July 2013. We searched the Cochrane Central Register of Controlled Trials (CENTRAL), PubMed, EMBASE (Ovid SP), the Cumulative Index to Nursing and Allied Health Literature (CINAHL) Plus (EBSCO Host), the Institute for Scientific Information Web of Science (ISI WOS) Scientific Citation Index (SCI)-EXPANDED (1970) and Conference Proceedings Citation Index (CPCI)-Science (1990) and Clinicaltrials.gov; we also screened reference lists. An updated search was run on 24 November 2014 but the results have not yet been incorporated into the review.

SELECTION CRITERIA

Two review authors independently selected references for further assessment by going through all titles and abstracts. Further selection was based on review of full-text articles for selected references.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted study data. We calculated the risk ratio (RR) with 95% confidence interval (CI) for binary outcomes and the mean difference (MD) or the standardised mean difference (SMD) with 95% CI for continuous outcomes. We performed meta-analysis when possible, when I(2) was less than or equal to 80% using a fixed-effect or random-effects model, using Review Manager software. The range of point estimates for individual studies is presented when I(2) > 80%.

MAIN RESULTS

We included in this systematic review 4745 participants who were randomly assigned in 21 trials. Trials were conducted in a wide variety of clinical settings. Most trials included participants with mild to moderate anaemia and excluded participants who were allergic to iron therapy. All trials were at high risk of bias for one or more domains. We compared both oral iron and parenteral iron versus inactive controls and compared different iron preparations.The comparison between oral iron and inactive control revealed no evidence of clinical benefit in terms of mortality (RR 1.05, 95% CI 0.68 to 1.61; four studies, N = 659; very low-quality evidence). The point estimate of the mean difference in haemoglobin levels in individual studies ranged from 0.3 to 3.1 g/dL higher in the oral iron group than in the inactive control group. The proportion of participants who required blood transfusion was lower with oral iron than with inactive control (RR 0.74, 95% CI 0.55 to 0.99; three studies, N = 546; very low-quality evidence). Evidence was inadequate for determination of the effect of parenteral iron on mortality versus oral iron (RR 1.49, 95% CI 0.56 to 3.94; 10 studies, N = 2141; very low-quality evidence) or inactive control (RR 1.04, 95% CI 0.63 to 1.69; six studies, N = 1009; very low-quality evidence). Haemoglobin levels were higher with parenteral iron than with oral iron (MD -0.50 g/dL, 95% CI -0.73 to -0.27; six studies, N = 769; very low-quality evidence). The point estimate of the mean difference in haemoglobin levels in individual studies ranged between 0.3 and 3.0 g/dL higher in the parenteral iron group than in the inactive control group. Differences in the proportion of participants requiring blood transfusion between parenteral iron and oral iron groups (RR 0.61, 95% CI 0.24 to 1.58; two studies, N = 371; very low-quality evidence) or between parenteral iron groups and inactive controls (RR 0.84, 95% CI 0.66 to 1.06; eight studies, N = 1315; very low-quality evidence) were imprecise. Average blood volume transfused was less in the parenteral iron group than in the oral iron group (MD -0.54 units, 95% CI -0.96 to -0.12; very low-quality evidence) based on one study involving 44 people. Differences between therapies in quality of life or in the proportion of participants with serious adverse events were imprecise (very low-quality evidence). No trials reported severe allergic reactions due to parenteral iron, suggesting that these are rare. Adverse effects related to oral iron treatment included nausea, diarrhoea and constipation; most were mild.Comparisons of one iron preparation over another for mortality, haemoglobin or serious adverse events were imprecise. No information was available on quality of life. Thus, little evidence was found to support the use of one preparation or regimen over another.Subgroup analyses did not reveal consistent results; therefore we were unable to determine whether iron is useful in specific clinical situations, or whether iron therapy might be useful for people who are receiving erythropoietin.

AUTHORS' CONCLUSIONS

• Very low-quality evidence suggests that oral iron might decrease the proportion of people who require blood transfusion, and no evidence indicates that it decreases mortality. Oral iron might be useful in adults who can tolerate the adverse events, which are usually mild.• Very low-quality evidence suggests that intravenous iron results in a modest increase in haemoglobin levels compared with oral iron or inactive control without clinical benefit.• No evidence can be found to show any advantage of one iron preparation or regimen over another.• Additional randomised controlled trials with low risk of bias and powered to measure clinically useful outcomes such as mortality, quality of life and blood transfusion requirements are needed.

A nanoparticulate ferritin-core mimetic is well taken up by HuTu 80 duodenal cells and its absorption in mice is regulated by body iron

BACKGROUND

Iron (Fe) deficiency anemia remains the largest nutritional deficiency disorder worldwide. How the gut acquires iron from nano Fe(III), especially at the apical surface, is incompletely understood.

OBJECTIVE

We developed a novel Fe supplement consisting of nanoparticulate tartrate-modified Fe(III) poly oxo-hydroxide [here termed nano Fe(III)], which mimics the Fe oxide core of ferritin and effectively treats iron deficiency anemia in rats.

METHODS

We determined transfer to the systemic circulation of nano Fe(III) in iron-deficient and iron-sufficient outbread Swiss mouse strain (CD1) mice with use of (59)Fe-labeled material. Iron deficiency was induced before starting the Fe-supplementation period through reduction of Fe concentrations in the rodent diet. A control group of iron-sufficient mice were fed a diet with adequate Fe concentrations throughout the study. Furthermore, we conducted a hemoglobin repletion study in which iron-deficient CD1 mice were fed for 7 d a diet supplemented with ferrous sulfate (FeSO4) or nano Fe(III). Finally, we further probed the mechanism of cellular acquisition of nano Fe(III) by assessing ferritin formation, as a measure of Fe uptake and utilization, in HuTu 80 duodenal cancer cells with targeted inhibition of divalent metal transporter 1 (DMT1) and duodenal cytochrome b (DCYTB) before exposure to the supplemented iron sources. Differences in gene expression were assessed by quantitative polymerase chain reaction.

RESULTS

Absorption (means ± SEMs) of nano Fe(III) was significantly increased in iron-deficient mice (58 ± 19%) compared to iron-sufficient mice (18 ± 17%) (P = 0.0001). Supplementation of the diet with nano Fe(III) or FeSO4 significantly increased hemoglobin concentrations in iron-deficient mice (170 ± 20 g/L, P = 0.01 and 180 ± 20 g/L, P = 0.002, respectively). Hepatic hepcidin mRNA expression reflected the nonheme-iron concentrations of the liver and was also comparable for both nano Fe(III)- and FeSO4-supplemented groups, as were iron concentrations in the spleen and duodenum. Silencing of the solute carrier family 11 (proton-coupled divalent metal ion transporter), member 2 (Slc11a2) gene (DMT1) significantly inhibited ferritin formation from FeSO4 (P = 0.005) but had no effect on uptake and utilization of nano Fe(III). Inhibiting DCYTB with an antibody also had no effect on uptake and utilization of nano Fe(III) but significantly inhibited ferritin formation from ferric nitrilotriacetate chelate (Fe-NTA) (P = 0.04). Similarly, cellular ferritin formation from nano Fe(III) was unaffected by the Fe(II) chelator ferrozine, which significantly inhibited uptake and utilization from FeSO4 (P = 0.009) and Fe-NTA (P = 0.005).

CONCLUSIONS

Our data strongly support direct nano Fe(III) uptake by enterocytes as an efficient mechanism of dietary iron acquisition, which may complement the known Fe(II)/DMT1 uptake pathway.

Ferrous sulfate (Fe2+) had a faster effect than did ferric polymaltose (Fe3+) on increased oxidant status in children with iron-deficiency anemia

OBJECTIVE

The purpose of this study was to compare the total oxidant and antioxidant effect of different oral iron preparations in children with iron-deficiency anemia (IDA).

METHODS

A total of 65 children with IDA were randomized to receive 5 mg Fe/kg/d iron (II) sulfate (Fe(2+) group, n=33) or iron (III)-hydroxide polymaltose complex (Fe(3+) group, n=32); healthy controls (n=28) were also included in the study. Serum total thiol (-SH), total antioxidant capacity (TAC), total oxidant status (TOS), oxidative stress index (OSI), and hematological profile were evaluated at the baseline and on day 8 and day 30 of the therapy.

RESULTS

Serum TOS and OSI levels were significantly higher and total -SH and total antioxidant capacity levels were significantly lower in the study groups at the beginning of therapy than in the controls (P>0.001). In multivariate analysis, after controlling for multiple confounding factors, on days 8 and 30, serum TOS and OSI levels were not different in the Fe(3+) group, whereas they were significantly reduced in the Fe(2+) group (P≤0.033).

CONCLUSIONS

Serum total oxidant status was significantly increased in children with IDA, and Fe(2+) was highly effective in correcting elevated oxidative status.

Iron-induced virulence of Salmonella enterica serovar typhimurium at the intestinal epithelial interface can be suppressed by carvacrol

Oral iron therapy can increase the abundance of bacterial pathogens, e.g., Salmonella spp., in the large intestine of African children. Carvacrol is a natural compound with antimicrobial activity against various intestinal bacterial pathogens, among which is the highly prevalent Salmonella enterica serovar Typhimurium. This study aimed to explore a presumed interaction between carvacrol and bacterial iron handling and to assess the potential of carvacrol in preventing the increase of bacterial pathogenicity during high iron availability. S. Typhimurium was cultured with increasing concentrations of iron and carvacrol to study the effects of these combined interventions on growth, adhesion to intestinal epithelial cells, and iron uptake/influx in both bacterial and epithelial cells. In addition, the ability of carvacrol to remove iron from the high-affinity ligand transferrin and an Fe-dye complex was examined. Carvacrol retarded growth of S. Typhimurium at all iron conditions. Furthermore, iron-induced epithelial adhesion was effectively reduced by carvacrol at high iron concentrations. The reduction of growth and virulence by carvacrol was not paralleled by a change in iron uptake or influx into S. Typhimurium. In contrast, bioavailability of iron for epithelial cells was moderately decreased under these conditions. Further, carvacrol was shown to lack the properties of an iron binding molecule; however, it was able to weaken iron-ligand interactions by which it may possibly interfere with bacterial virulence. In conclusion, our in vitro data suggest that carvacrol has the potential to serve as a novel dietary supplement to prevent pathogenic overgrowth and colonization in the large intestine during oral iron therapy.