Sensorimotor neurotoxicity associated with high-dose deferoxamine treatment

Clinical Challenges with Iron Chelation in Beta Thalassemia

Conventional therapy for severe thalassemia includes regular red cell transfusions and iron chelation therapy to prevent and treat complications of iron overload. Iron chelation is very effective when appropriately used, but inadequate iron chelation therapy continues to contribute to preventable morbidity and mortality in transfusion-dependent thalassemia. Factors that contribute to suboptimal iron chelation include poor adherence, variable pharmacokinetics, chelator adverse effects, and difficulties with precise monitoring of response. The regular assessment of adherence, adverse effects, and iron burden with appropriate treatment adjustments is necessary to optimize patient outcomes.

Neuroprotective Role of α-Lipoic Acid in Iron-Overload-Mediated Toxicity and Inflammation in In Vitro and In Vivo Models

Hemoglobin and iron overload is considered the major contributor to intracerebral hemorrhage (ICH)-induced brain injury. Accumulation of iron in the brain leads to microglia activation, inflammation and cell loss. Current available treatments for iron overload-mediated disorders are characterized by severe adverse effects, making such conditions an unmet clinical need. We assessed the potential of α-lipoic acid (ALA) as an iron chelator, antioxidant and anti-inflammatory agent in both in vitro and in vivo models of iron overload. ALA was found to revert iron-overload-induced toxicity in HMC3 microglia cell line, preventing cell apoptosis, reactive oxygen species generation and reducing glutathione depletion. Furthermore, ALA regulated gene expression of iron-related markers and inflammatory cytokines, such as IL-6, IL-1β and TNF. Iron toxicity also affects mitochondria fitness and biogenesis, impairments which were prevented by ALA pre-treatment in vitro. Immunocytochemistry assay showed that, although iron treatment caused inflammatory activation of microglia, ALA treatment resulted in increased ARG1 expression, suggesting it promoted an anti-inflammatory phenotype. We also assessed the effects of ALA in an in vivo zebrafish model of iron overload, showing that ALA treatment was able to reduce iron accumulation in the brain and reduced iron-mediated oxidative stress and inflammation. Our data support ALA as a novel approach for iron-overload-induced brain damage.

Hearing Loss in Beta-Thalassemia: Systematic Review

In the last half century, the life expectancy of beta-thalassemia patients has strikingly increased mostly due to regular blood transfusions and chelation treatments. The improved survival, however, has allowed for the emergence of comorbidities, such as hearing loss, with a non-negligible impact on the patients' quality of life. This thorough review analyzes the acquired knowledge regarding hearing impairment in this hereditary hemoglobinopathy, aiming at defining its prevalence, features, course, and possible disease- or treatment-related pathogenic factors. Following PRISMA criteria, we retrieved 60 studies published between 1979 and 2021. Diagnostic tools and criteria, forms of hearing impairment, correlations with beta-thalassemia phenotypes, age and sex, chelation treatment and laboratory findings including iron overload, were carefully searched, analyzed and summarized. In spite of the relatively high number of studies in the last 40 years, our knowledge is rather limited, and large prospective studies with homogeneous diagnostic tools and criteria are required to define all the aforementioned issues. According to the literature, the overall prevalence rate of hearing impairment is 32.3%; age, sex, and laboratory findings do not seem to correlate with hearing deficits, while the weak relationship with clinical phenotype and chelation treatment seems to highlight the presence of further yet to be identified pathogenic factors.

Polyneuropathy Associated with Severe Iron Overload and Oxidative Stress in β-Thalassemia Patients

To investigate the frequency of peripheral neuropathy in patients with β-thalassemia, and to assess its relation to iron overload and oxidative stress. Sixty β-thalassemia patients with mean age of 19 ± 4.9 years were recruited. Serum ferritin was quantitatively assessed by enzyme-linked immunoassay and biomarkers of oxidative stress were estimated calorimetrically. Electrophysiological studies using NEMUS 2, Galileu Software were carried out. The patients were separated into two groups: those with abnormal nerve conduction studies (NCS) {Group A; N = 38} and those with normal NCS {Group B; N = 22}. Thirty-eight (63.3%) patients had axonal motor neuropathy as evidenced by abnormal NCS (group A), they showed higher mean serum ferritin (p < 0.01), higher mean malondialdehyde (MDA) (p < 0.01), and lower mean nitrous oxide, total antioxidant capacity, paraoxonase-1 (PON1) (p < 0.01) compared to group B. Bivariate analysis of NCS data demonstrated that abnormal NCS were more frequent in splenectomized patients (p = 0.002), and poorly-chelated patients with serum ferritin ≥ 2000 ng/ml (p = 0.001). Significant variables associated with abnormal motor NCS were entered in stepwise regression analysis and only elevated serum ferritin (p = 0.01) was independently associated with abnormal motor NCS (p = 0.02; 95% CI 1.433-51.791). None of the studied patients had sensory neuropathy or myopathy. Peripheral motor neuropathy may occur in β-thalassemia patients at a high frequency, regardless of their age and gender. Severe iron overload may contribute to the pathogenesis of neuropathy. Other factors including chelation therapy, splenectomy, and oxidative stress might have an enhancing effect that couldn't be proved in this study.

Therapeutic Macromolecular Iron Chelators

Iron is a key element for every single living process. On a fundamental level, targeting iron is a valuable approach for the treatment of disorders caused by iron overload. Utilizing iron chelators as therapeutic agents has received expanding consideration in chelation therapy. Approved low molecular weight (MW) iron chelators to treat iron overload may experience short half-lives and toxicities prompting moderately high adverse effects. In recent years, polymeric/macromolecular iron chelators have received attention as therapeutic agents. Polymeric iron chelators show unique pharmaceutical properties that are different to their conventional small molecule counterparts. These polymeric iron chelators possess longer plasma half-lives and reduced toxicities, thus exhibiting a significant supplement to currently using low MW iron chelator therapy. In this review, we have briefly discussed polymeric iron chelators and factors to be considered when designing clinically valuable iron chelators. We have also discussed applications of polymeric iron chelators in the diseases caused by iron overload associated with transfusional hemosiderosis, neurodegenerative disorders, malaria and cancer. With this, research findings for new polymeric iron chelators are also covered.

ROS-triggered degradable iron-chelating nanogels: Safely improving iron elimination in vivo

Iron-mediated generation of highly toxic Reactive Oxygen Species (ROS) plays a major role in the process leading to iron overload-related diseases. The long-term subcutaneous administration of Deferoxamine (DFO) is currently clinically-approved to improve patient symptoms and survival. However, non-specific toxicity and short circulation times of the drug in humans often leads to poor patient compliance. Herein, thioketal-based ROS-responsive polymeric nanogels containing DFO moieties (rNG-DFO) were designed to chelate iron and to degrade under oxidative stimuli into fragments <10 nm to enhance excretion of iron-bound chelates. Serum ferritin levels and iron concentrations in major organs of IO mice decreased following treatment with rNG-DFO, and fecal elimination of iron-bound chelates increased compared to free DFO. Furthermore, rNG-DFO decreased iron mediated oxidative stress levels in vitro and reduced iron-mediated inflammation in the liver of IO mice. The study confirms that ROS-responsive nanogels may serve as a promising alternative to DFO for safer and more efficient iron chelation therapy.

Nanogel-DFO conjugates as a model to investigate pharmacokinetics, biodistribution, and iron chelation in vivo

Deferoxamine (DFO) to treat iron overload (IO) has been limited by toxicity issues and short circulation times and it would be desirable to prolong circulation to improve non-transferrin bound iron (NTBI) chelation. In addition, DFO is currently unable to efficiently target the large pool of iron in the liver and spleen. Nanogel-Deferoxamine conjugates (NG-DFO) can prove useful as a model to investigate the pharmacokinetic (PK) properties and biodistribution (BD) behavior of iron-chelating macromolecules and their overall effect on serum ferritin levels. NG-DFO reduced the cytotoxicity of DFO and significantly reduced cellular ferritin levels in IO macrophages in vitro. PK/BD studies in normal rats revealed that NG-DFO displayed prolonged circulation and preferential accumulation into the liver and spleen. IO mice treated with NG1-DFO presented significantly lower levels of serum ferritin compared to DFO. Total renal and fecal elimination data point to the need to balance prolonged circulation with controlled degradation to accelerate clearance of iron-chelating macromolecules.

Epigallocatechin Gallate Has a Neurorescue Effect in a Mouse Model of Parkinson Disease

Background: Parkinson disease (PD) is a neurodegenerative disorder that has been associated with many factors, including oxidative stress, inflammation, and iron accumulation. The antioxidant, anti-inflammatory, and iron-chelating properties of epigallocatechin gallate (EGCG), a major polyphenol in green tea, may offer protection against PD.Objective: We sought to determine the neurorescue effects of EGCG and the role of iron in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD.Methods: We evaluated the neurorescue effect of EGCG (25 mg/kg, 7 d, oral administration) against MPTP-induced (20 mg/kg, 3 d, intraperitoneal injection) neurodegeneration in C57 male black mice. Thirty mice weighing ∼25 g were divided into 3 groups: control, MPTP, and MPTP + EGCG. The neurorescue effect of EGCG was assessed with the use of motor behavior tests, neurotransmitter analysis, oxidative stress indicators, and iron-related protein expression.Results: Compared with the control group, MPTP treatment shortened the mice's latency to fall from the rotarod by 16% (P < 0.05), decreased the striatal dopamine concentration by 58% (P < 0.001) and dihydroxyphenylacetic acid by 35% (P < 0.05), and increased serum protein carbonyls by 71% (P = 0.07). However, EGCG rescued MPTP-induced neurotoxicity by increasing the rotational latency by 17% (P < 0.05) to a value similar to the control group. Striatal dopamine concentrations were 40% higher in the MPTP + EGCG group than in the MPTP group (P < 0.05), but the values were significantly lower than in the control group. Compared with the MPTP and control groups, mice in the MPTP + EGCG group had higher substantia nigra ferroportin expression (44% and 35%, respectively) (P < 0.05) but not hepcidin and divalent metal transporter 1 expression.Conclusion: Overall, our study demonstrated that EGCG regulated the iron-export protein ferroportin in substantia nigra, reduced oxidative stress, and exerted a neurorescue effect against MPTP-induced functional and neurochemical deficits in mice.

Multifunctional Polymeric Micelles for Combining Chelation and Detection of Iron in Living Cells

Multifunctional self-assembled micelles composed of Pluronics F127 polymer chains are developed and investigated for chelation and selective detection of iron(III) in vitro and in iron-overloaded cells. Tetraphenylethene (TPE) is encapsulated into the micelle core and the iron chelate drug deferoxamine (DFO) is conjugated to micelles to generate a fluorescence quenching detection system termed DFO-TFM for short, where T stands for TPE, F for F127, and M for micelle. The key to the successful formation of this fluorescence quenching system is due to the near-ideal overlap between the absorption spectrum of the DFO:iron(III) complex and fluorescence spectrum of TPE. DFO-TFM can retain the iron-chelation properties of DFO and exhibits negligible cytotoxicity compared to free DFO. Furthermore, this fluorescence "turn-off" system can be utilized to detect the presence of iron and to monitor the chelation process in an iron overload cell model. This study serves as an effective proof-of-concept model for designing future in vivo systems capable of combining the features of iron chelation with iron detection and efforts toward the development of such detection systems are currently underway.

Safety profiles of iron chelators in young patients with haemoglobinopathies

BACKGROUND

This review describes the safety of deferoxamine (DFO), deferiprone (DFP), deferasirox (DFX) and combined therapy in young patients less than 25 yr of age with haemoglobinopathies.

METHODS

Searches in electronic literature databases were performed. Studies reporting adverse events associated with iron chelation therapy were included. Study and reporting quality was assessed using AHRQ Risk of Bias Assessment Tool and McMaster Quality Assessment Scale of Harms. Prospective clinical studies were pooled in a random-effects meta-analysis of proportions.

RESULTS

Safety data of 2040 patients from 34 studies were included. Ninety-two case reports of 246 patients were identified. DFX (937 patients) and DFP (667 patients) possess the largest published safety evidence. Fewer studies on combination regimens are available. Increased transaminases were seen in all regimens (3.9-31.3%) and gastrointestinal disorders with DFP and DFX (3.7-18.4% and 5.8-18.8%, respectively). Therapy discontinuations due to adverse events were low (0-4.1%). Reporting quality was selective and poor in most of the studies.

CONCLUSION

Iron chelation therapy is generally safe in young patients, and published data correspond to summary of product characteristics. Each iron chelation regimen has its specific safety risks. DFO seems not to be associated with serious adverse effects in recommended doses. In DFP and DFX, rare, but serious, adverse reactions can occur. Data on combined therapy are scarce, but it seems equally safe compared to monotherapy.

Polymeric nanocarriers for the treatment of systemic iron overload

Desferrioxamine (DFO), deferiprone (L1) and desferasirox (ICL-670) are clinically approved iron chelators used to treat secondary iron overload. Although iron chelators have been utilized since the 1960s and there has been much improvement in available therapy, there is still the need for new drug candidates due to limited long-term efficacy and drug toxicity. Moreover, all currently approved iron chelators are of low molecular weight (MW) (<600 Da) and the objectives reported for the “ideal” chelator of low MW, including possessing the ability to promote iron excretion without causing toxic side effects, has proven difficult to realize in practice. With prolonged iron chelator use, patients may develop toxicities or become insensitive. In contrast, the limited research that has been geared towards developing higher MW, polymeric, long circulating iron chelators has shown promise. The inherent potential of polymeric iron chelators toward longer plasma half-lives and reduction in toxicity provides optimism and may be a significant addition to the currently available low MW iron chelators. This article reviews knowledge pertaining to this theme, highlights some unique advantages that these nanomedicines have in treating systemic iron overload as well as their potential utility in the treatment of other disease states.

Polymeric nanocarriers for the treatment of systemic iron overload

Desferrioxamine (DFO), deferiprone (L1) and desferasirox (ICL-670) are clinically approved iron chelators used to treat secondary iron overload. Although iron chelators have been utilized since the 1960s and there has been much improvement in available therapy, there is still the need for new drug candidates due to limited long-term efficacy and drug toxicity. Moreover, all currently approved iron chelators are of low molecular weight (MW) (<600 Da) and the objectives reported for the "ideal" chelator of low MW, including possessing the ability to promote iron excretion without causing toxic side effects, has proven difficult to realize in practice. With prolonged iron chelator use, patients may develop toxicities or become insensitive. In contrast, the limited research that has been geared towards developing higher MW, polymeric, long circulating iron chelators has shown promise. The inherent potential of polymeric iron chelators toward longer plasma half-lives and reduction in toxicity provides optimism and may be a significant addition to the currently available low MW iron chelators. This article reviews knowledge pertaining to this theme, highlights some unique advantages that these nanomedicines have in treating systemic iron overload as well as their potential utility in the treatment of other disease states.

Clinically approved iron chelators influence zebrafish mortality, hatching morphology and cardiac function

Iron chelation therapy using iron (III) specific chelators such as desferrioxamine (DFO, Desferal), deferasirox (Exjade or ICL-670), and deferiprone (Ferriprox or L1) are the current standard of care for the treatment of iron overload. Although each chelator is capable of promoting some degree of iron excretion, these chelators are also associated with a wide range of well documented toxicities. However, there is currently very limited data available on their effects in developing embryos. In this study, we took advantage of the rapid development and transparency of the zebrafish embryo, Danio rerio to assess and compare the toxicity of iron chelators. All three iron chelators described above were delivered to zebrafish embryos by direct soaking and their effects on mortality, hatching and developmental morphology were monitored for 96 hpf. To determine whether toxicity was specific to embryos, we examined the effects of chelator exposure via intra peritoneal injection on the cardiac function and gene expression in adult zebrafish. Chelators varied significantly in their effects on embryo mortality, hatching and morphology. While none of the embryos or adults exposed to DFO were negatively affected, ICL -treated embryos and adults differed significantly from controls, and L1 exerted toxic effects in embryos alone. ICL-670 significantly increased the mortality of embryos treated with doses of 0.25 mM or higher and also affected embryo morphology, causing curvature of larvae treated with concentrations above 0.5 mM. ICL-670 exposure (10 µL of 0.1 mM injection) also significantly increased the heart rate and cardiac output of adult zebrafish. While L1 exposure did not cause toxicity in adults, it did cause morphological defects in embryos at 0.5 mM. This study provides first evidence on iron chelator toxicity in early development and will help to guide our approach on better understanding the mechanism of iron chelator toxicity.

Evaluation and treatment of transfusional iron overload in children

Red blood cell transfusions are increasingly used in the management of various anemias, including thalassemia and sickle cell disease. Because the body lacks physiologic mechanisms for removing excess iron, transfusional iron overload is a common complication in children receiving regular transfusions. Iron chelation is necessary to remove the excess iron that causes injury to the heart, liver, and endocrine organs. Three chelators, deferoxamine, deferasirox, and deferiprone, are currently available in the United States. When choosing a chelator regimen, patients, parents, and providers may consider a variety of factors, including the severity of iron overload, administration schedule, and adverse effect profile.

Management of transfusional iron overload - differential properties and efficacy of iron chelating agents

Regular red cell transfusion therapy ameliorates disease-related morbidity and can be lifesaving in patients with various hematological disorders. Transfusion therapy, however, causes progressive iron loading, which, if untreated, results in endocrinopathies, cardiac arrhythmias and congestive heart failure, hepatic fibrosis, and premature death. Iron chelation therapy is used to prevent iron loading, remove excess accumulated iron, detoxify iron, and reverse some of the iron-related complications. Three chelators have undergone extensive testing to date: deferoxamine, deferasirox, and deferiprone (although the latter drug is not currently licensed for use in North America where it is available only through compassionate use programs and research protocols). These chelators differ in their modes of administration, pharmacokinetics, efficacy with regard to organ-specific iron removal, and adverse-effect profiles. These differential properties influence acceptability, tolerability and adherence to therapy, and, ultimately, the effectiveness of treatment. Chelation therapy, therefore, must be individualized, taking into account patient preferences, toxicities, ongoing transfusional iron intake, and the degree of cardiac and hepatic iron loading.

Real-world use of iron chelators

Whereas RBC transfusion therapy is lifesaving in thalassemia, obligatory iron loading accompanies such treatment and chelation therapy to remove and detoxify iron resulting from these chronic transfusions must therefore be administered. Morbidity and mortality in thalassemia is linked closely to the adequacy of chelation. Three chelators are currently available worldwide-deferoxamine, deferasirox, and deferiprone, although the latter is available in North America only in research protocols and compassionate use programs. These chelators can be used as monotherapy or in combination, although only the combination of deferiprone and deferoxamine has been extensively studied to date. Several factors, including chelator availability and its properties, drug tolerability, degree of organ-specific iron loading, ongoing transfusional iron burden, and patient preference, must be considered in the design of optimal, individualized chelation regimens, and these factors must periodically be reviewed and chelation adjusted accordingly. Ultimately, comparative effectiveness trials may help to determine the ideal strategy (eg, intensification of monotherapy or combined therapy including agents and doses) for treating various scenarios of organ-specific iron loading.

Safety and efficacy of high dose intravenous desferrioxamine for reduction of iron overload in sickle cell disease

BACKGROUND

Patients with sickle cell disease (SCD) receiving chronic blood transfusions are at risk of developing iron overload and organ toxicity. Chelation therapy with either subcutaneous (SQ) desferrioxamine (DFO) or oral deferasirox is effective in preventing and reducing iron overload but poses significant challenges with patient compliance. Intravenous (IV) infusions of high dose DFO have been utilized in non-compliant patients with heavy iron overload in small case series.

PROCEDURE

We review our experience of high dose IV DFO in 27 patients with SCD who had significant iron overload and were noncompliant with subcutaneous (SQ) DFO. All patients were treated in-hospital with DFO 15 mg/kg/hr IV for 48 hr every 2-4 weeks with a mean duration of 19.6 months.

RESULTS

We observed a significant decrease in liver iron burden with high dose intermittent IV DFO. Histological examination of liver biopsies revealed a decrease in the grade of liver iron storage. Also there was significant improvement in liver enzymes (ALT, AST) after high dose IV DFO. No audiologic or ophthalmologic toxicity or acute or chronic pulmonary complications were observed.

CONCLUSIONS

In our cohort of patients with SCD we observed a significant decrease in liver iron burden with high dose IV DFO. Our patients tolerated the therapy well without any major toxicity. This regimen is safe and may be an option for poorly compliant patients with significant iron overload.

New insights into the exercise intolerance of beta-thalassemia major patients

The purpose of our study was assessment of the relative contribution of the systems involved in blood gas exchange to the limited exercise capacity in patients with beta-thalassemia major (TM) using integrative cardiopulmonary exercise testing (CPET) with estimation of oxygen kinetics. The study consisted of 15 consecutive TM patients and 15 matched controls who performed spirometric evaluation, measurement of maximum inspiratory pressure (Pimax) and an incremental symptom-limited CPET on a cycle ergometer. Exercise capacity was markedly reduced in TM patients as assessed by peak oxygen uptake (pVO(2), mL/kg/min: 22.1+/-6.6 vs 33.8+/-8.3; P<0.001) and anaerobic threshold (mL/kg/min: 13.0+/-3.0 vs 18.7+/-4.6; P<0.001) compared with controls. No ventilatory limitation to exercise was noted in TM patients (VE/VCO(2) slope: 23.4+/-3.2 vs 27.8+/-2.6; P<0.001 and breathing reserve, %: 42.9+/-17.0 vs 29.5+/-12.0; P<0.005) and no difference in oxygen cost of work (peak VO(2)/WR, mL/min W: 12.2+/-1.7 vs 12.2+/-1.5; P=NS). Delayed recovery oxygen kinetics after exercise was observed in TM patients (VO(2)/t slope, mL/kg/min(2): 0.67+/-0.27 vs 0.93+/-0.23; P<0.05) that was significantly correlated with Pimax at rest (r: 0.81; P<0.001). The latter was also significantly correlated to pVO(2) (r: 0.84; P<0.001) and inversely correlated to ferritin levels (r: -0.6; P<0.02). Exercise capacity is markedly reduced in TM patients and this reduction is highly associated with the limited functional status of peripheral muscles.

Immune and neural status of thalassemic patients receiving deferiprone or combined deferiprone and deferoxamine chelation treatment

Deferiprone (L1), has previously been reported to be associated with immunological abnormalities in iron loaded thalassemia patients. However, other factors may also have similar effects such as the level of iron overload, chronic immuno-stimulation due to transfusions, splenectomy and deferoxamine (DFO). During chelation therapy with DFO, several complications have been reported, which were due to pharmacological activity and high dose toxicity with regard to both acoustic and visual effects, as well as peripheral nerve disorders that were measured by nerve conduction velocities. The immune and neural status of 44 beta-thalassemic patients, aged 10-30 years (mean 19.4 +/- 4.9), receiving L1 as a monotherapy (n = 21), or in combination with DFO (n = 23), has been followed for 2 years by monitoring the level of immunoglobulins (IgG, IgM, IgA), the level of T and B lymphocytes (CD4/CD8), the auto antibodies: anti nuclear (ANA), anti-double-stranded (anti-ds DNA), anti reticulin (anti-R1), anti-extra nuclear (anti-ENA), anti histone (anti-AHA), anti liver-kidney-muscle (anti-LKM), anti-smooth muscle (anti-SMA), anti-thyroid (anti-ATA), anti-mitochondrial (anti-AMA) antibodies and the C-reactive protein. The percentage of patients with disorders of the immune and nervous system concerned very few cases. None of our patients with pathological findings in their immunological or neurophysiological examinations presented any signs or symptoms of involvement of the immune or nervous system. Further advantages have been identified for the oral use of L1 and its combination with DFO, including synergistic efficacy and lower dosing with limited toxicity.

Neurological complications in beta-thalassemia

Over the years, several reports have demonstrated involvement of the nervous system in beta-thalassemia patients. Neurological complications have been attributed to various factors such as chronic hypoxia, bone marrow expansion, iron overload, and desferrioxamine neurotoxicity. In most cases, neurological involvement does not initially present with relevant signs or symptoms (i.e., is subclinical) and can only be detected during neurophysiological or neuroimaging evaluation. Abnormal findings in the visual, auditory, and somatosensory evoked potential recordings are mainly attributed to DFO neurotoxicity. On the other hand, nerve conduction velocity abnormalities are associated either to chronic hypoxia and older age or to hemosiderosis, whether by means of pancreas involvement or not. Neuropsychological studies available reveal a considerably high prevalence of abnormal IQ, not correlating, however, to factors such as hypoxia or iron overload. It is proposed that factors associated to severe chronic illness, rather than the disease per se, could be responsible for these findings. Such factors include regular school absence due to transfusions and frequent hospitalizations, physical and social restrictions resulting from the disease and its treatment, abnormal mental state due to the awareness of being chronically ill, and, last, the overly protective family attitude that leads to restricted initiative and psychosocial development. As life expectancy for beta-thalassemia patients extends, the use of neurophysiologic and neuropsychologic monitoring becomes imperative, enabling early detection of neural pathway impairment and allowing for appropriate management, in order to achieve a better life quality for this patient group.

Weekend very high-dose intravenous deferoxamine in children with transfusional iron overload

Iron overload can be a major complication in children requiring chronic red cell transfusions. Compliance with subcutaneous deferoxamine is often poor. We report the use of very high-dose deferoxamine in 14 children. Patients received intravenous deferoxamine at 15 mg/kg/h over 48 hours every 2 or 4 weeks. The mean duration of treatment was 18 months. Therapy was well tolerated and our regimen was successful in removing excess iron. Intermittent very high-dose intravenous deferoxamine is practical, safe, and effective in managing iron overload in children. Treatment can be given as an outpatient without a central venous catheter.

Acute renal failure following deferoxamine overdose

A 17-year-old patient with sickle cell-beta thalassemia undergoing treatment with home iron chelation therapy inadvertently received ten times the recommended dose of intravenous deferoxamine. Acute renal failure (ARF) developed within hours. Immediate treatment with high-efficiency hemodialysis resulted in the prompt return of renal function after only one hemodialysis session. No long-term nephrotoxic effects of the deferoxamine overdose developed after more than 1 year of follow-up. Children with sickle cell disease who are on intravenous deferoxamine and their parents should be cautioned about the possibility of ARF with overdose due to malfunction of the pump and/or inadequate monitoring during treatment. ARF, should it occur in such children, appears to respond well to treatment with high-efficiency hemodialysis.

Exogenous apotransferrin and exchange transfusions in hereditary iron overload disease

OBJECTIVE

To investigate whether apotransferrin administration and exchange transfusion can improve outcome in patients with the recently described recessive congenital iron overload disease, presenting with intrauterine growth retardation, severe lactic acidosis, aminoaciduria, and hemosiderosis of the liver that so far has been treatment-resistant and lethal.

METHODOLOGY

Because the patients have hypotransferrinemia, hyperferritinemia, increased transferrin saturation, and bleomycin detectable iron in plasma, we designed a treatment regime aiming at decreasing free iron and iron overload. The serum transferrrin concentration was increased to adult level (2-5 g/L) by intravenous apotransferrin administrations and thereafter exchange transfusion was performed.

RESULTS

Two patients were treated. In patient 1, the transferrin saturation decreased from a baseline value of 100% and remained normal after the third exchange transfusion, and in patient 2, a reversible beneficial effect was seen on transferrin saturation and bleomycin-detectable iron. However, both infants died later of the disease, at 10 and 8 weeks of age, respectively.

CONCLUSIONS

Exogenous apotransferrin administration proved to be safe and might deserve evaluation in other neonatal diseases with presence of free iron in plasma.