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Kontoghiorghes GJ. The Importance and Essentiality of Natural and Synthetic Chelators in Medicine: Increased Prospects for the Effective Treatment of Iron Overload and Iron Deficiency. Int J Mol Sci 2024; 25:4654. [PMID: 38731873 PMCID: PMC11083551 DOI: 10.3390/ijms25094654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2024] [Revised: 04/19/2024] [Accepted: 04/22/2024] [Indexed: 05/13/2024] Open
Abstract
The supply and control of iron is essential for all cells and vital for many physiological processes. All functions and activities of iron are expressed in conjunction with iron-binding molecules. For example, natural chelators such as transferrin and chelator-iron complexes such as haem play major roles in iron metabolism and human physiology. Similarly, the mainstay treatments of the most common diseases of iron metabolism, namely iron deficiency anaemia and iron overload, involve many iron-chelator complexes and the iron-chelating drugs deferiprone (L1), deferoxamine (DF) and deferasirox. Endogenous chelators such as citric acid and glutathione and exogenous chelators such as ascorbic acid also play important roles in iron metabolism and iron homeostasis. Recent advances in the treatment of iron deficiency anaemia with effective iron complexes such as the ferric iron tri-maltol complex (feraccru or accrufer) and the effective treatment of transfusional iron overload using L1 and L1/DF combinations have decreased associated mortality and morbidity and also improved the quality of life of millions of patients. Many other chelating drugs such as ciclopirox, dexrazoxane and EDTA are used daily by millions of patients in other diseases. Similarly, many other drugs or their metabolites with iron-chelation capacity such as hydroxyurea, tetracyclines, anthracyclines and aspirin, as well as dietary molecules such as gallic acid, caffeic acid, quercetin, ellagic acid, maltol and many other phytochelators, are known to interact with iron and affect iron metabolism and related diseases. Different interactions are also observed in the presence of essential, xenobiotic, diagnostic and theranostic metal ions competing with iron. Clinical trials using L1 in Parkinson's, Alzheimer's and other neurodegenerative diseases, as well as HIV and other infections, cancer, diabetic nephropathy and anaemia of inflammation, highlight the importance of chelation therapy in many other clinical conditions. The proposed use of iron chelators for modulating ferroptosis signifies a new era in the design of new therapeutic chelation strategies in many other diseases. The introduction of artificial intelligence guidance for optimal chelation therapeutic outcomes in personalised medicine is expected to increase further the impact of chelation in medicine, as well as the survival and quality of life of millions of patients with iron metabolic disorders and also other diseases.
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Affiliation(s)
- George J Kontoghiorghes
- Postgraduate Research Institute of Science, Technology, Environment and Medicine, Limassol 3021, Cyprus
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Chapin J, Giardina PJ. Thalassemia Syndromes. Hematology 2018. [DOI: 10.1016/b978-0-323-35762-3.00040-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
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Botzenhardt S, Li N, Chan EW, Sing CW, Wong ICK, Neubert A. Safety profiles of iron chelators in young patients with haemoglobinopathies. Eur J Haematol 2017; 98:198-217. [PMID: 27893170 DOI: 10.1111/ejh.12833] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/08/2016] [Indexed: 12/19/2022]
Abstract
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.
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Affiliation(s)
- Sebastian Botzenhardt
- Department of Paediatrics and Adolescent Medicine, Faculty of Medicine, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Niya Li
- Department of Pharmacology and Pharmacy, Li Ka Shing Faculty of Medicine, Centre for Safe Medication Practice and Research, University of Hong Kong, Hong Kong, China.,Clinical Trials Center, The University of Hong Kong - Shenzhen Hospital, Shenzhen, China
| | - Esther W Chan
- Department of Pharmacology and Pharmacy, Li Ka Shing Faculty of Medicine, Centre for Safe Medication Practice and Research, University of Hong Kong, Hong Kong, China
| | - Chor Wing Sing
- Department of Pharmacology and Pharmacy, Li Ka Shing Faculty of Medicine, Centre for Safe Medication Practice and Research, University of Hong Kong, Hong Kong, China
| | - Ian C K Wong
- Department of Pharmacology and Pharmacy, Li Ka Shing Faculty of Medicine, Centre for Safe Medication Practice and Research, University of Hong Kong, Hong Kong, China.,Research Department of Practice & Policy, University College London School of Pharmacy, London, UK
| | - Antje Neubert
- Department of Paediatrics and Adolescent Medicine, Faculty of Medicine, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen, Germany
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Fisher SA, Brunskill SJ, Doree C, Gooding S, Chowdhury O, Roberts DJ. Desferrioxamine mesylate for managing transfusional iron overload in people with transfusion-dependent thalassaemia. Cochrane Database Syst Rev 2013:CD004450. [PMID: 23963793 DOI: 10.1002/14651858.cd004450.pub3] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
BACKGROUND Thalassaemia major is a genetic disease characterised by a reduced ability to produce haemoglobin. Management of the resulting anaemia is through red blood cell transfusions.Repeated transfusions result in an excessive accumulation of iron in the body (iron overload), removal of which is achieved through iron chelation therapy. Desferrioxamine mesylate (desferrioxamine) is one of the most widely used iron chelators. Substantial data have shown the beneficial effects of desferrioxamine, although adherence to desferrioxamine therapy is a challenge. Alternative oral iron chelators, deferiprone and deferasirox, are now commonly used. Important questions exist about whether desferrioxamine, as monotherapy or in combination with an oral iron chelator, is the best treatment for iron chelation therapy. OBJECTIVES To determine the effectiveness (dose and method of administration) of desferrioxamine in people with transfusion-dependent thalassaemia.To summarise data from trials on the clinical efficacy and safety of desferrioxamine for thalassaemia and to compare these with deferiprone and deferasirox. SEARCH METHODS We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Haemoglobinopathies Trials Register. We also searched MEDLINE, EMBASE, CENTRAL (The Cochrane Library), LILACS and other international medical databases, plus ongoing trials registers and the Transfusion Evidence Library (www.transfusionevidencelibrary.com). All searches were updated to 5 March 2013. SELECTION CRITERIA Randomised controlled trials comparing desferrioxamine with placebo, with another iron chelator, or comparing two schedules or doses of desferrioxamine, in people with transfusion-dependent thalassaemia. DATA COLLECTION AND ANALYSIS Six authors working independently were involved in trial quality assessment and data extraction. For one trial, investigators supplied additional data upon request. MAIN RESULTS A total of 22 trials involving 2187 participants (range 11 to 586 people) were included. These trials included eight comparisons between desferrioxamine alone and deferiprone alone; five comparisons between desferrioxamine combined with deferiprone and deferiprone alone; eight comparisons between desferrioxamine alone and desferrioxamine combined with deferiprone; two comparisons of desferrioxamine with deferasirox; and two comparisons of different routes of desferrioxamine administration (bolus versus continuous infusion). Overall, few trials measured the same or long-term outcomes. Seven trials reported cardiac function or liver fibrosis as measures of end organ damage; none of these included a comparison with deferasirox.Five trials reported a total of seven deaths; three in patients who received desferrioxamine alone, two in patients who received desferrioxamine and deferiprone. A further death occurred in a patient who received deferiprone in another who received deferasirox alone. One trial reported five further deaths in patients who withdrew from randomised treatment (deferiprone with or without desferrioxamine) and switched to desferrioxamine alone.One trial planned five years of follow up but was stopped early due to the beneficial effects of a reduction in serum ferritin levels in those receiving combined desferrioxamine and deferiprone treatment compared with deferiprone alone. The results of this and three other trials suggest an advantage of combined therapy with desferrioxamine and deferiprone over monotherapy to reduce iron stores as measured by serum ferritin. There is, however, no evidence for the improved efficacy of combined desferrioxamine and deferiprone therapy against monotherapy from direct or indirect measures of liver iron.Earlier trials measuring the cardiac iron load indirectly by measurement of the magnetic resonance imaging T2* signal had suggested deferiprone may reduce cardiac iron more quickly than desferrioxamine. However, meta-analysis of two trials showed a significantly lower left ventricular ejection fraction in patients who received desferrioxamine alone compared with those who received combination therapy using desferrioxamine with deferiprone.Adverse events were recorded by 18 trials. These occurred with all treatments, but were significantly less likely with desferrioxamine than deferiprone in one trial, relative risk 0.45 (95% confidence interval 0.24 to 0.84) and significantly less likely with desferrioxamine alone than desferrioxamine combined with deferiprone in two other trials, relative risk 0.33 (95% confidence interval 0.13 to 0.84). In particular, four studies reported permanent treatment withdrawal due to adverse events from deferiprone; only one of these reported permanent withdrawals associated with desferrioxamine. Adverse events also occurred at a higher frequency in patients who received deferasirox than desferrioxamine in one trial. Eight trials reported local adverse reactions at the site of desferrioxamine infusion including pain and swelling. Adverse events associated with deferiprone included joint pain, gastrointestinal disturbance, increases in liver enzymes and neutropenia; adverse events associated with deferasirox comprised increases in liver enzymes and renal impairment. Regular monitoring of white cell counts has been recommended for deferiprone and monitoring of liver and renal function for deferasirox.In summary, desferrioxamine and the oral iron chelators deferiprone and deferasirox produce significant reductions in iron stores in transfusion-dependent, iron-overloaded people. There is no evidence from randomised clinical trials to suggest that any one of these has a greater reduction of clinically significant end organ damage, although in two trials, combination therapy with desferrioxamine and deferiprone showed a greater improvement in left ventricular ejection fraction than desferrioxamine used alone. AUTHORS' CONCLUSIONS Desferrioxamine is the recommended first-line therapy for iron overload in people with thalassaemia major and deferiprone or deferasirox are indicated for treating iron overload when desferrioxamine is contraindicated or inadequate. Oral deferasirox has been licensed for use in children aged over six years who receive frequent blood transfusions and in children aged two to five years who receive infrequent blood transfusions. In the absence of randomised controlled trials with long-term follow up, there is no compelling evidence to change this conclusion.Worsening iron deposition in the myocardium in patients receiving desferrioxamine alone would suggest a change of therapy by intensification of desferrioxamine treatment or the use of desferrioxamine and deferiprone combination therapy.Adverse events are increased in patients treated with deferiprone compared with desferrioxamine and in patients treated with combined deferiprone and desferrioxamine compared with desferrioxamine alone. People treated with all chelators must be kept under close medical supervision and treatment with deferiprone or deferasirox requires regular monitoring of neutrophil counts or renal function respectively. There is an urgent need for adequately-powered, high-quality trials comparing the overall clinical efficacy and long-term outcomes of deferiprone, deferasirox and desferrioxamine.
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Affiliation(s)
- Sheila A Fisher
- Systematic Review Initiative, NHS Blood and Transplant, Level 2, John Radcliffe Hospital, Headington, Oxford, Oxon, UK, OX3 9BQ
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Azoulay E. Pleuropulmonary Changes Induced by Drugs in Patients with Hematologic Diseases. PULMONARY INVOLVEMENT IN PATIENTS WITH HEMATOLOGICAL MALIGNANCIES 2011. [PMCID: PMC7123804 DOI: 10.1007/978-3-642-15742-4_31] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
Patients with hematologic diseases who are being treated with therapy drugs, or receive radiation therapy or blood transfusions may develop a host of potentially fatal infectious and noninfectious pulmonary complications [1]. The increased complexity of multimodality and high-dose treatment regimens with the intended benefit of augmented antineoplastic efficacy and prolonged disease-free survival, the use of a panel of novel drugs to treat malignant and nonmalignant hematologic conditions (e.g., azacytidine, bortezomib, cladribine, dasatinib, fludarabine, imatinib, lenalidomide, rituximab, and thalidomide), total body irradiation (TBI) and hematopietic stem cell transplantation (HSCT) have increased the incidence of severe sometimes life-threatening pulmonary complications.
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Affiliation(s)
- Elie Azoulay
- Service de Réanimation Médicale, Hôpital Saint Louis, Avenue Claude Vellefaux 1, Paris, 75010 France
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Somech R, Seaban-Adel K, Atkinson A, Kirby-Allen M. Evaluation and management of pediatric patients with anaphylactoid reactions to deferoxamine mesylate. Ann Allergy Asthma Immunol 2008; 99:575-6. [PMID: 18219844 DOI: 10.1016/s1081-1206(10)60392-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Abuelo JG, Shemin D, Chazan JA. Acute Symptoms Produced by Hemodialysis: A Review of Their Causes and Associations. Semin Dial 2007. [DOI: 10.1111/j.1525-139x.1993.tb00257.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Roberts DJ, Rees D, Howard J, Hyde C, Alderson P, Brunskill S. Desferrioxamine mesylate for managing transfusional iron overload in people with transfusion-dependent thalassaemia. Cochrane Database Syst Rev 2005:CD004450. [PMID: 16235363 DOI: 10.1002/14651858.cd004450.pub2] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BACKGROUND Thalassaemia major is a genetic disease characterised by a reduced ability to produce haemoglobin. Management of the resulting anaemia is through transfusions of red blood cells. Repeated transfusions results in excessive accumulation of iron in the body (iron overload), removal of which is achieved through iron chelation therapy. Desferrioxamine is the most widely used iron chelator. Substantial data have shown the beneficial effects of desferrioxamine. However, important questions exist about whether desferrioxamine is the best schedule for iron chelation therapy. OBJECTIVES To determine the effectiveness (dose and method of administration) of desferrioxamine in people with transfusion-dependent thalassaemia. SEARCH STRATEGY We searched the Cochrane Haemoglobinopathies Trials Register, MEDLINE, EMBASE, ZETOC, Current Controlled Trials and bibliographies of relevant publications. We also contacted the manufacturers of desferrioxamine and other iron chelators. Date of last searches: April 2004. SELECTION CRITERIA Randomised controlled trials comparing desferrioxamine with placebo; with another iron chelator; or comparing two schedules of desferrioxamine, in people with transfusion-dependent thalassaemia. DATA COLLECTION AND ANALYSIS Four authors working independently, were involved in trial quality assessment and data extraction. Missing data were requested from the original investigators. MAIN RESULTS Eight trials involving 334 people (range 20 to 144 people) were included. One trial compared desferrioxamine with placebo, five compared desferrioxamine with another iron chelator (deferiprone) and two compared different schedules of desferrioxamine. Overall, few trials measured the same outcomes.Compared to placebo, desferrioxamine significantly reduced iron overload. The number of deaths at 12 years follow up and evidence of reduced end-organ damage was less for desferrioxamine than placebo. When desferrioxamine was compared to deferiprone or a different desferrioxamine schedule there were no statistically significant differences in measures of iron overload. Compliance was recorded by two trials. Compliance was less for desferrioxamine than deferiprone in one trial and of no difference in comparison with desferrioxamine and deferiprone combined with a second trial. Adverse events were recorded in trials comparing desferrioxamine with other iron chelators. There was evidence of adverse events in all treatment groups. In one trial, adverse events were significantly less likely with desferrioxamine than deferiprone, relative risk 0.45 (95% confidence interval 0.24 to 0.84). Assessment of the methodological quality of included trials was not possible, given the general absence of these data in the trials. AUTHORS' CONCLUSIONS We found no reason to change current treatment recommendations. However, considerable uncertainty continues to exist about the optimal schedule for desferrioxamine in people with transfusion-dependent thalassaemia.
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Affiliation(s)
- D J Roberts
- National Blood Service, Systematic Review Initiative, Level 2, John Radcliffe Hospital, Headley Way, Oxford, Oxon, UK OX3 9BQ.
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Roberts D, Rees D, Howard J, Hyde C, Stanworth S, Brunskill S. Desferrioxamine mesylate for managing transfusional iron overload in people with thalassaemia. THE COCHRANE DATABASE OF SYSTEMATIC REVIEWS 2003. [DOI: 10.1002/14651858.cd004450] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Kontoghiorghes GJ, Neocleous K, Kolnagou A. Benefits and risks of deferiprone in iron overload in Thalassaemia and other conditions: comparison of epidemiological and therapeutic aspects with deferoxamine. Drug Saf 2003; 26:553-84. [PMID: 12825969 DOI: 10.2165/00002018-200326080-00003] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Deferiprone is the only orally active iron-chelating drug to be used therapeutically in conditions of transfusional iron overload. It is an orphan drug designed and developed primarily by academic initiatives for the treatment of iron overload in thalassaemia, which is endemic in the Mediterranean, Middle East and South East Asia and is considered an orphan disease in the European Union and North America. Deferiprone has been used in several other iron or other metal imbalance conditions and has prospects of wider clinical applications. Deferiprone has high affinity for iron and interacts with almost all the iron pools at the molecular, cellular, tissue and organ levels. Doses of 50-120 mg/kg/day appear to be effective in bringing patients to negative iron balance. It increases urinary iron excretion, which mainly depends on the iron load of patients and the dose of the drug. It decreases serum ferritin levels and reduces the liver and heart iron content in the majority of chronically transfused iron loaded patients at doses >80 mg/kg/day. It is metabolised to a glucuronide conjugate and cleared through the urine in the metabolised and a non-metabolised form, usually of a 3 deferiprone: 1 iron complex, which gives the characteristic red colour urine. Peak serum levels of deferiprone are observed within 1 hour of its oral administration and clearance from blood is within 6 hours. There is variation among patients in iron excretion, the metabolism and pharmacokinetics of deferiprone. Deferiprone has been used in more than 7500 patients aged from 2-85 years in >50 countries, in some cases daily for >14 years. All the adverse effects of deferiprone are considered reversible, controllable and manageable. These include agranulocytosis with frequency of about 0.6%, neutropenia 6%, musculoskeletal and joint pains 15%, gastrointestinal complains 6% and zinc deficiency 1%. Discontinuation of the drug is recommended for patients developing agranulocytosis. Deferiprone is of similar therapeutic index to subcutaneous deferoxamine but is more effective in iron removal from the heart, which is the target organ of iron toxicity and mortality in iron-loaded thalassaemia patients. Deferiprone is much less expensive to produce than deferoxamine. Combination therapy of deferoxamine and deferiprone has been used in patients not complying with subcutaneous deferoxamine or experiencing toxicity or not excreting sufficient amounts of iron with use of either drug alone. New oral iron-chelating drugs are being developed, but even if successful these are likely to be more expensive than deferiprone and are not likely to become available in the next 5-8 years. About 25% of treated thalassaemia patients in Europe and more than 50% in India are using deferiprone. For most thalassaemia patients worldwide who are not at present receiving any form of chelation therapy the choice is between deferiprone and fatal iron toxicity.
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Affiliation(s)
- George J Kontoghiorghes
- Postgraduate Research Institute of Science, Technology, Environment and Medicine, Limassol, Cyprus.
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Bergeron RJ, Wiegand J, McManis JS, Weimar WR, Huang G. Structure-activity relationships among desazadesferrithiocin analogues. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2003; 509:167-84. [PMID: 12572994 DOI: 10.1007/978-1-4615-0593-8_9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Desferrithiocin, a natural product iron chelator (siderophore), offers an excellent platform from which to construct orally active iron chelators which have a good therapeutic window. A systematic structure-activity study on desferrithiocin identified the structural fragments necessary for the compound's oral iron-clearing activity. There are strict requirements regarding the distance between the ligating centers; they cannot be altered without loss of efficacy. The thiazoline ring must remain intact. Benz-fusions, which were designed to improve the ligands' tissue residence time and possibly iron-clearing efficiency, are ineffective. The maintenance of an (S)-configured C-4 carbon is optimal in the design of desferrithiocin-based iron chelators. With this information in hand, alteration of the redox potential of the aromatic ring was initiated. Introduction of a hydroxy in the 4'-position of at least three different desazadesferrithiocin analogues resulted in moderate to small changes in iron clearing efficacy yet dramatic reductions in the toxicity of the compounds were observed. Although the toxicity studies of these desferrithiocin analogues are continuing, it is clear that it is possible to alter a siderophore in such a way as to ameliorate its toxicity profile while maintaining its iron-clearing properties.
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Affiliation(s)
- Raymond J Bergeron
- Department of Medicinal Chemistry, University of Florida, Gainesville, Florida 32610, USA
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Davis BA, Porter JB. Results of long term iron chelation treatment with deferoxamine. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2003; 509:91-125. [PMID: 12572991 DOI: 10.1007/978-1-4615-0593-8_6] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Bernard A Davis
- Department of Haematology, Royal Free and University College London Medical School, 98 Chenies Mews, London, WC1E 6HX, UK
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Bergeron RJ, Wiegand J, McManis JS, Bussenius J, Smith RE, Weimar WR. Methoxylation of desazadesferrithiocin analogues: enhanced iron clearing efficiency. J Med Chem 2003; 46:1470-7. [PMID: 12672247 DOI: 10.1021/jm020412d] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The impact of altering the octanol-water partition properties (log P) of analogues of desazadesferrithiocin, (S)-4,5-dihydro-2-(2-hydroxyphenyl)-4-methyl-4-thiazolecarboxylic acid, on the ligands' iron clearing properties is described. Increasing chelator lipophilicity can both substantially augment iron clearing efficiency in Cebus apella primates as well as alter the mode of iron excretion, favoring fecal over urinary output. The complications of iron overload are often associated with the metal's interaction with hydrogen peroxide, generating hydroxyl radicals (Fenton chemistry) and, ultimately, other related deleterious species. In fact, some iron chelators actually promote this chemistry. All of the compounds synthesized and tested in the current study are shown to be both inhibitors of the iron-mediated oxidation of ascorbate, thus removing the metal from the Fenton cycle, and effective radical scavengers.
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Affiliation(s)
- Raymond J Bergeron
- Department of Medicinal Chemistry, University of Florida, Gainesville 32610-0485, USA.
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Abstract
In patients with transfusion-dependent anemias, iron accumulation is fatal in the absence of chelating therapy. Extended survival, free of most complications of iron overload is observed in patients treated with early, adequate parenteral deferoxamine. Despite its success in prevention and treatment of iron toxicity, the expense and inconvenience of this therapy have stimulated a continued quest for an effective chelating agent that is orally active. Unfortunately, studies emerging over the last five years have confirmed that the most widely administered orally active agent, deferiprone (L1; 1,2-dimethyl-3-hydropyrid-4-one) may be harmfully ineffective in many patients: 18-65% of patients in six studies which obtained hepatic irons after long term deferiprone treatment had body iron exceeding the threshold for cardiac disease and premature death. The impact of deferiprone on cardiac and liver disease must be evaluated further, while the association between deferiprone and accelerated hepatic fibrosis still awaits refutation in large prospective trials. In view of the striking therapeutic successes of deferoxamine over the past 20 years, administration of deferiprone outside the setting of prospective clinical trials may need to be reconsidered. Meanwhile, an orally active iron chelator of demonstrated safety and effectiveness remains an objective for development for transfused patients.
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Affiliation(s)
- L Merson
- Toronto General Hospital, 200 St Elizabeth Street, CW-3-338, 101 College Street M5G 2C4, Toronto, Canada.
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Bergeron RJ, Wiegand J, Brittenham GM. HBED ligand: preclinical studies of a potential alternative to deferoxamine for treatment of chronic iron overload and acute iron poisoning. Blood 2002; 99:3019-26. [PMID: 11929795 DOI: 10.1182/blood.v99.8.3019] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We have continued the preclinical evaluation of the efficacy and safety of the hexadentate phenolic aminocarboxylate iron chelator N, N'-bis(2-hydroxybenzyl) ethylenediamine-N, N'-diacetic acid monosodium salt (NaHBED) for the treatment of both chronic transfusional iron overload and acute iron poisoning. We examined the effect of route of administration by giving equimolar amounts of NaHBED and deferoxamine (DFO) to Cebus apella monkeys as either a subcutaneous (SC) bolus or a 20-minute intravenous (IV) infusion. By both routes, NaHBED was consistently about twice as efficient as DFO in producing iron excretion. For both chelators at a dose of 150 micromol/kg, SC was more efficient than IV administration. The biochemical and histopathologic effects of NaHBED administration were assessed. No systemic toxicity was found after either IV administration once daily for 14 days to iron-loaded dogs or after SC administration every other day for 14 days to dogs without iron overload. Evidence of local irritation was found at some SC injection sites. When the NaHBED concentration was reduced to 15% or less in a volume comparable to a clinically useful one, no local irritation was found with SC administration in rats. Because treatment of acute iron poisoning may require rapid chelator infusion, we compared the effects of IV bolus administration of the compounds to normotensive rats. Administration of DFO produced a prompt, prolonged drop in blood pressure and acceleration of heart rate; NaHBED had little effect. NaHBED may provide an alternative to DFO for the treatment of both chronic transfusional iron overload and of acute iron poisoning.
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Affiliation(s)
- Raymond J Bergeron
- Department of Medicinal Chemistry, University of Florida, Gainesville 32610, USA.
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Affiliation(s)
- J B Porter
- University College London, Thalassaemia and Sickle Unit UCL Hospitals, London, UK.
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Bergeron RJ, Xin MG, Weimar WR, Smith RE, Wiegand J. Significance of asymmetric sites in choosing siderophores as deferration agents. J Med Chem 2001; 44:2469-78. [PMID: 11448229 DOI: 10.1021/jm010019s] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The syntheses of the microbial iron chelators L-fluviabactin, its unnatural enantiomer, D-fluviabactin, L-homofluviabactin, and L-agrobactin, are described. The key steps involve the selective bis-acylation of the terminal nitrogens of norspermidine, spermidine, or homospermidine with 2,3-bis(benzyloxy)benzoic acid in the presence of 1,1-carbonyldiimidazole, followed by coupling of the N-hydroxysuccinimide ester of CBZ-protected L- or D-threonine with the central nitrogen. The effectiveness of each of these ligands in supporting the growth of Paracoccus denitrificans in a low-iron environment and the ability of these compounds to promote iron uptake are evaluated. The stereochemical configuration of the oxazoline ring is shown to be the major structural factor controlling both microbial growth stimulation and iron uptake. L-Fluviabactin, L-homofluviabactin, and L-agrobactin all promoted growth and iron uptake; D-fluviabactin was only marginally active. As with the microorganism's native siderophore, L-parabactin, all three ligands in the L-configuration investigated exhibited biphasic, i.e., both high-affinity and low-affinity, kinetics. The high-affinity system (iron concentration < 1 microM) yielded K(m) values between 0.11 and 0.23 microM and V(max) values from 157 to 129 pg-atoms Fe min(-1) (mg of protein)(-1), whereas the low-affinity scheme (iron concentration > 1 microM) gave K(m) values from 0.53 to 3.5 microM and V(max) values between 96 and 413 pg-atoms Fe min(-1) (mg of protein)(-1). Both L- and D-fluviabactin are very effective at clearing iron from the bile duct-cannulated rodent; when given subcutaneously at a dose of 150 micromol/kg, both ligands had iron clearing efficiencies of >13%, which is much greater than that of desferrioxamine in this model. Thus, by altering the stereochemistry of certain microbial siderophores, it is possible to generate deferration agents that are still effective at clearing iron from animals, yet do not promote microbial growth.
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Affiliation(s)
- R J Bergeron
- Department of Medicinal Chemistry, University of Florida, J. Hillis Miller Health Science Center, Gainesville, Florida 32610, USA.
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19
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Kushner JP, Porter JP, Olivieri NF. Secondary iron overload. HEMATOLOGY. AMERICAN SOCIETY OF HEMATOLOGY. EDUCATION PROGRAM 2001; 2001:47-61. [PMID: 11722978 DOI: 10.1182/asheducation-2001.1.47] [Citation(s) in RCA: 142] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Transfusion therapy for inherited anemias and acquired refractory anemias both improves the quality of life and prolongs survival. A consequence of chronic transfusion therapy is secondary iron overload, which adversely affects the function of the heart, the liver and other organs. This session will review the use of iron chelating agents in the management of transfusion-induced secondary iron overload. In Section I Dr. John Porter describes techniques for the administration of deferoxamine that exploit the pharmacokinetic properties of the drug and minimize potential toxic side effects. The experience with chelation therapy in patients with thalassemia and sickle cell disease will be reviewed and guidelines will be suggested for chelation therapy of chronically transfused adults with refractory anemias. In Section II Dr. Nancy Olivieri examines the clinical consequences of transfusion-induced secondary iron overload and suggests criteria useful in determining the optimal timing of the initiation of chelation therapy. Finally, Dr. Olivieri discusses the clinical trials evaluating orally administered iron chelators.
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Affiliation(s)
- J P Kushner
- Department of Hematology, University College London, 98 Chenies Mews, London WC1 6HX
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20
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HBED: The Continuing Development of a Potential Alternative to Deferoxamine for Iron-Chelating Therapy. Blood 1999. [DOI: 10.1182/blood.v93.1.370.401k29_370_375] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
To further examine the potential clinical usefulness of the hexadentate phenolic aminocarboxylate iron chelatorN,N′-bis(2-hydroxybenzyl)ethylenediamine-N,N′-diacetic acid (HBED) for the chronic treatment of transfusional iron overload, we performed a subchronic toxicity study of the HBED monosodium salt in rodents and have evaluated the iron excretion in primates induced by HBED. The HBED-induced iron excretion was determined for the monohydrochloride dihydrate that was first dissolved in a 0.1-mmol/L sodium phosphate buffer at pH 7.6 and administered to the primates either orally (PO) at a dose of 324 μmol/kg (149.3 mg/kg, n = 5), subcutaneously (sc) at a dose of 81 μmol/kg (37.3 mg/kg, n = 5), sc at 324 μmol/kg (n = 5), and sc at 162 μmol/kg (74.7 mg/kg) for 2 consecutive days for a total dose of 324 μmol/kg (n = 3). In addition, the monosodium salt of HBED in saline was administered to the monkeys sc at a single dose of 150 μmol/kg (64.9 mg/kg, n = 5) or at a dose of 75 μmol/kg every other day for three doses, for a total dose of 225 μmol/kg (n = 4). For comparative purposes, we have also administered deferoxamine (DFO) PO and sc in aqueous solution at a dose of 300 μmol/kg (200 mg/kg). In the iron-loadedCebus apella monkey, whereas the PO administration of DFO or HBED even at a dose of 300 to 324 μmol/kg was ineffective, the sc injection of HBED in buffer or its monosodium salt, 75 to 324 μmol/kg, produced a net iron excretion that was nearly three times that observed after similar doses of sc DFO. In patients with transfusional iron overload, sc injections of HBED may provide a much needed alternative to the use of prolonged parenteral infusions of DFO. Note: After the publication of our previous paper (Blood, 91:1446, 1998) and the completion of the studies described here, it was discovered that the HBED obtained from Strem Chemical Co (Newburyport, MA) that was labeled and sold as a dihydrochloride dihydrate was in fact the monohydrochloride dihydrate. Therefore, the actual administered doses were 81, 162, or 324 μmol/kg; not 75, 150, or 300 μmol/kg as was previously reported. The new data have been recalculated accordingly, and the data from our earlier study, corrected where applicable, are shown in parentheses.
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21
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HBED: The Continuing Development of a Potential Alternative to Deferoxamine for Iron-Chelating Therapy. Blood 1999. [DOI: 10.1182/blood.v93.1.370] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Abstract
To further examine the potential clinical usefulness of the hexadentate phenolic aminocarboxylate iron chelatorN,N′-bis(2-hydroxybenzyl)ethylenediamine-N,N′-diacetic acid (HBED) for the chronic treatment of transfusional iron overload, we performed a subchronic toxicity study of the HBED monosodium salt in rodents and have evaluated the iron excretion in primates induced by HBED. The HBED-induced iron excretion was determined for the monohydrochloride dihydrate that was first dissolved in a 0.1-mmol/L sodium phosphate buffer at pH 7.6 and administered to the primates either orally (PO) at a dose of 324 μmol/kg (149.3 mg/kg, n = 5), subcutaneously (sc) at a dose of 81 μmol/kg (37.3 mg/kg, n = 5), sc at 324 μmol/kg (n = 5), and sc at 162 μmol/kg (74.7 mg/kg) for 2 consecutive days for a total dose of 324 μmol/kg (n = 3). In addition, the monosodium salt of HBED in saline was administered to the monkeys sc at a single dose of 150 μmol/kg (64.9 mg/kg, n = 5) or at a dose of 75 μmol/kg every other day for three doses, for a total dose of 225 μmol/kg (n = 4). For comparative purposes, we have also administered deferoxamine (DFO) PO and sc in aqueous solution at a dose of 300 μmol/kg (200 mg/kg). In the iron-loadedCebus apella monkey, whereas the PO administration of DFO or HBED even at a dose of 300 to 324 μmol/kg was ineffective, the sc injection of HBED in buffer or its monosodium salt, 75 to 324 μmol/kg, produced a net iron excretion that was nearly three times that observed after similar doses of sc DFO. In patients with transfusional iron overload, sc injections of HBED may provide a much needed alternative to the use of prolonged parenteral infusions of DFO. Note: After the publication of our previous paper (Blood, 91:1446, 1998) and the completion of the studies described here, it was discovered that the HBED obtained from Strem Chemical Co (Newburyport, MA) that was labeled and sold as a dihydrochloride dihydrate was in fact the monohydrochloride dihydrate. Therefore, the actual administered doses were 81, 162, or 324 μmol/kg; not 75, 150, or 300 μmol/kg as was previously reported. The new data have been recalculated accordingly, and the data from our earlier study, corrected where applicable, are shown in parentheses.
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Bergeron RJ, Wiegand J, Ratliff-Thompson K, Weimar WR. The origin of the differences in (R)- and (S)-desmethyldesferrithiocin. Iron-clearing properties. Ann N Y Acad Sci 1998; 850:202-16. [PMID: 9668541 DOI: 10.1111/j.1749-6632.1998.tb10476.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The iron clearance properties, toxicity, and pharmacokinetics of (R)- and (S)-desmethyldesferrithiocin (DMDFT) are described. The studies were performed in rodent and primate models. While both enantiomers were found to be effective iron chelators with minimal toxicity in the rodents, only (S)-DMDFT was able to induce the clearance of any iron in the primates. In addition, two out of nine of the monkeys given (R)-DMDFT died within 24 h of drug administration. The reason for the differences in iron clearance properties and the apparent toxicity of the (R)-enantiomer in the primates is likely related to the disparities in the pharmacokinetics of the two analogues. The pharmacokinetic data suggest enantioselectivity in renal clearance of the desferrithiocins and their iron complexes with (S)-DMDFT clearance 3.5 times greater than that of (R)-DMDFT, and FeIII [(S)-DMDFT]2 clearance 6.8 times greater than that of FeIII [R-DMDFT]2. In all primates studied FeIII [(R)-DMDFT]2 in the plasma exceeded 25 mg/L (50 microM) for several hours and remained above 10 mg/L (20 microM) at 8 h while levels of FeIII [(S)-DMDFT]2 never exceeded 50 microM and were at or below the limits of detection 8 h post-injection.
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Affiliation(s)
- R J Bergeron
- Department of Medicinal Chemistry, University of Florida, Gainesville 32610, USA.
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23
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Abstract
Advances in the management of thalassaemia major have greatly improved the prognosis for patients with this disease. In countries able to afford programmes of regular transfusion and iron-chelating therapy, survival to the fourth decade is now common, and most complications associated with the primary disease are now infrequently observed. This situation stands in contrast to that in emerging countries, where the widespread implementation of these expensive treatment regimens is still awaited. This review will focus on recent advances in the treatment of thalassaemia and briefly review the progress in experimental approaches to treatment of this disorder.
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Affiliation(s)
- N Olivieri
- Division of Hematology/Oncology, Hospital for Sick Children, Toronto, Ontario, Canada
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24
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Abstract
AbstractTo examine the potential clinical usefulness of the hexadentate phenolic aminocarboxylate iron chelatorN,N-bis(2-hydroxybenzyl)ethylenediamine-N,N-diacetic acid (HBED) for the chronic treatment of transfusional iron overload, we compared the iron excretion induced by subcutaneous (SC) injection of HBED and deferoxamine (DFO), the reference chelator, in rodents and primates. In the non–iron-overloaded, bile-duct–cannulated rat, a single SC injection of HBED, 150 μmol/kg, resulted in a net iron excretion that was more than threefold greater than that after the same dose of DFO. In the iron-loaded Cebus apella monkey, a single SC injection of HBED, 150 μmol/kg, produced a net iron excretion that was more than twice that observed after the same dose of SC DFO. In patients with transfusional iron overload, SC injections of HBED may provide a much needed alternative to the use of prolonged parenteral infusions of DFO.
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25
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La Rosa M, Romeo MA, Di Gregorio F, Russo G. Desensitization treatment for anaphylactoid reactions to desferrioxamine in a pediatric patient with thalassemia. J Allergy Clin Immunol 1996; 97:127-8. [PMID: 8568125 DOI: 10.1016/s0091-6749(96)70291-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- M La Rosa
- Department of Pediatrics, University of Catania, Italy
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26
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Howland MA. Risks of parenteral deferoxamine for acute iron poisoning. JOURNAL OF TOXICOLOGY. CLINICAL TOXICOLOGY 1996; 34:491-7. [PMID: 8800186 DOI: 10.3109/15563659609028006] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
OBJECTIVE To review the adverse effects and risks of deferoxamine for the treatment of iron poisoning. METHODS A literature search of deferoxamine induced adverse effects was used to identify pertinent articles. The references of these articles served as the source of other references not previously identified. RESULTS Deferoxamine is a relatively safe antidote for iron intoxication, but adverse effects have been recognized with increased usage, particularly with prolonged intravenous dosing. This paper focuses on deferoxamine induced cardiovascular, pulmonary, ocular and auditory toxicity as well as its potential to increase the risk of infection. Information on iron's toxicology and toxicokinetics and deferoxamine's pharmacology and pharmacokinetics are reviewed. With this background information a hypothesis is generated to maximize deferoxamine benefit while minimizing deferoxamine induced pulmonary toxicity. The hypothesis is based upon a stoichiometric approach to maximal chelation during the first 24 h following iron ingestion. CONCLUSION Deferoxamine is a relatively safe antidote for iron poisoning but the potential for pulmonary and cardiovascular toxicity should be respected. Studies defining maximum regimens over defined periods of time will allow a more logical utilization of deferoxamine, optimizing benefit and minimizing risk.
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27
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Donikyan R, Leblanc A. [Anaphylactoid reaction to desferrioxamine]. Arch Pediatr 1995; 2:703. [PMID: 7663670 DOI: 10.1016/0929-693x(96)81236-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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28
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Kontoghiorghes GJ, Weinberg ED. Iron: mammalian defense systems, mechanisms of disease, and chelation therapy approaches. Blood Rev 1995; 9:33-45. [PMID: 7795423 DOI: 10.1016/0268-960x(95)90038-1] [Citation(s) in RCA: 97] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
During the past 6 decades, much attention has been devoted to understanding the uses, metabolism and hazards of iron in living systems. A great variety of heme and non-heme iron-containing enzymes have been characterized in nearly all forms of life. The existence of both ferrous and ferric ions in low- and high-spin configuration, as well as the ability of the metal to function over a wide range of redox potentials, contributes to its unique versatility. Not surprisingly, the singular attributes of iron that permit it to be so useful to life likewise render the metal dangerous to manipulate and to sequester. All vertebrate animals are prone to tissue damage from exposure to excess iron. In order to protect them from this threat, a complex system has evolved to contain and detoxify this metal. This is known as the iron withholding defense system, which mainly serves to scavenge toxic quantities of iron and also for depriving microbial and neoplastic invaders of iron essential for their growth. Since 1970, medical scientists have become increasingly aware of the problems involved in cellular iron homeostasis and of the disease states related to its malfunctioning. Scores of studies have reported that excessive iron in specific tissue sites is associated with development of infection, neoplasia, cardiomyopathy, arthropathy and a variety of endocrine and neurologic deficits. Accordingly, several research groups have attempted to develop chemical agents that might prevent and even eliminate deposits of excess iron. A few of these drugs now are in clinical use, e.g. deferiprone (L1). In the present review, we focus on recent developments in (i) selected aspects of the iron withholding defense system, and (ii) pharmacologic methods that can assist the iron-burdened patient.
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Affiliation(s)
- G J Kontoghiorghes
- Department of Haematology, Royal Free Hospital School of Medicine, University of London
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29
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Steinberg DG, Borish LC, Rosenwasser LJ. Pharmacologic desensitization by intravenous protocols. ARTHRITIS AND RHEUMATISM 1992; 35:842-3. [PMID: 1622426 DOI: 10.1002/art.1780350727] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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30
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Affiliation(s)
- C Hershko
- Department of Medicine, Shaare Zedek Medical Center, Jerusalem, Israel
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31
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Shalit M, Tedeschi A, Miadonna A, Levi-Schaffer F. Desferal (desferrioxamine)--a novel activator of connective tissue-type mast cells. J Allergy Clin Immunol 1991; 88:854-60. [PMID: 1720796 DOI: 10.1016/0091-6749(91)90241-f] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The effect of Desferal (desferrioxamine), an iron-chelating agent with allergic side effects, was examined on human basophils and rodent mast cells (MCs) in vitro and in the human skin. Even at a high concentration (100 mg/ml), the drug neither induced histamine release (HR) from human basophils nor primed these cells to release higher amounts of histamine when they were activated with f-met-peptide or anti-IgE antibodies. In contrast, in all seven subjects studied, intradermal injection of Desferal (0.1 mg/ml to 100 mg/ml) elicited classic wheal-and-flare responses. Ingestion of 10 mg of cetirizine, an H1 antagonist, 3 hours before the intracutaneous administration of Desferal, significantly reduced the diameters of both wheal-and-flare reactions, indicating that the drug caused local HR. Desferal also induced HR from rat peritoneal MCs in vitro but had no effect on mouse bone marrow-derived MCs. These results suggest that Desferal has a direct, IgE-independent, stimulatory effect on connective tissue-type MCs. Thus, it may be used as a positive control in skin testing.
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Affiliation(s)
- M Shalit
- Division of Medicine, Hadassah Medical Center, Jerusalem, Israel
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32
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Abstract
Iron excretion in response to DF in humans is dependent upon the degree of iron overload, particularly of parenchymal liver cells. However, a number of variables, including ascorbate status, erythroid activity and liver disease, affect both the amount of iron mobilized and the route by which it is excreted. Faecal iron, derived from the bile, appears to arise from intracellular chelation of a transit iron pool related to hepatocyte iron stores, whereas urine iron may be derived from iron capable of exchanging with plasma transferrin at cell membranes of both hepatocytes and macrophages. Faecal iron predominates as iron stores return towards normal on regular chelation therapy. An understanding of the variables which influence iron excretion allows rational planning of long-term therapy with DF in patients with iron-loading anaemias. In young children a dose of 40-50 mg/kg given on five or six nights a week from the age of about 3 years is appropriate for prevention of serious iron loading. In older children the dose must be carefully tailored (by means of an individual urinary iron excretion dose-response curve) to achieve maximum safe chelation of pre-existing iron stores. In patients with slower rates of iron loading from excessive gastrointestinal iron absorption, intermittent use of DF infusions may be sufficient to maintain normal iron stores.
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Abstract
DF has a low general toxicity, perhaps because of its low lipid solubility, Kpart 0.01 (Porter et al, 1988b). This feature of the molecule may prevent it from penetrating most cells of the body. It appears that there may be a specific mechanism of uptake of the drug by hepatocytes (Porter et al, 1987), making the iron in these cells available for excretion via the bile, while the iron excreted in the urine may all come from extracellular chelation, particularly when iron leaves the reticuloendothelial cells (Hershko et al, 1978). On this hypothesis, cellular toxicity occurs only when DF penetrates sensitive cells in sufficient amounts so that some free DF remains after all the available iron in such cells has been chelated. Such a hypothesis accounts for the protection of cells by iron overload and therefore the greater sensitivity of unloaded patients. The retina and central nervous system are further protected by the blood-retinal or blood-brain barrier, and increased penetration of this barrier, mediated by high peak levels of DF, by drugs or other diseases would lead to the retinal or neurotoxic effects seen. In the ear, high levels of unliganded DF for a period of time may be necessary to cause deafness. Thus the very property that prevents its oral activity may be part of the reason for the low toxicity of DF. The severe toxic effects on vision, hearing and growth are all more likely at higher doses of DF and there appears to be partial protection against them by iron overload. These two conclusions have to be taken into account when deciding on the appropriate dosage for each patient. With care, the dosage can be adjusted to remove enough iron to prevent iron accumulation and therefore its toxic effects, whilst keeping doses low enough to prevent DF from being toxic itself. It appears that even in very iron-overloaded patients dosages higher than 125 mg kg-1 day-1 may cause visual disturbances and should be avoided. In patients on renal dialysis with aluminium toxicity great care is needed to avoid retinal toxicity even with dosages as low as 50 mg kg-1 day-1, although the drug should not be withheld if clinically indicated. The administration of DF to renal dialysis patients is described by Pogglitsch et al (1981, 1983), Pacitti et al (1983), Ihle et al (1986) and Molitoris et al (1987). DF should not be given to patients unless there is a clearly established clinical indication.(ABSTRACT TRUNCATED AT 400 WORDS)
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Wonke B, Hoffbrand AV, Aldouri M, Wickens D, Flynn D, Stearns M, Warner P. Reversal of desferrioxamine induced auditory neurotoxicity during treatment with Ca-DTPA. Arch Dis Child 1989; 64:77-82. [PMID: 2923478 PMCID: PMC1791794 DOI: 10.1136/adc.64.1.77] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Auditory neurotoxicity occurred in 13 (26%) of 50 evaluable patients receiving long term desferrioxamine chelation. In five of these patients, all of whom were receiving high doses of desferrioxamine, the toxicity caused deafness. These five patients were treated with subcutaneous calcium diethylene triamine pentacetic acid (Ca-DTPA) with zinc supplements instead of desferrioxamine, and their hearing improved during periods of seven to 19 months. Their serum ion concentrations remained unchanged. We suggest that all patients receiving long term desferrioxamine should have audiometric assessments at 6-12 monthly intervals. Ca-DTPA with oral zinc supplements should be considered as alternative to desferrioxamine as an iron chelating treatment in patients with auditory neurotoxicity.
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Affiliation(s)
- B Wonke
- Department of Haematology, Whittington Hospital, London
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Freedman MH. Management of beta-thalassemia major using transfusions and iron chelation with deferoxamine. Transfus Med Rev 1988; 2:161-75. [PMID: 2980085 DOI: 10.1016/s0887-7963(88)70041-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- M H Freedman
- Division of Hematology/Oncology, Hospital for Sick Children, Department of Pediatrics, University of Toronto, Canada
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36
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Abstract
Because of the catalytic action of iron in one-electron redox reactions, it has a key role in the formation of harmful oxygen derivatives and production of peroxidative damage to vital cellular structures. The clinical manifestations of iron overload may be prevented and even reversed by the effective administration of the iron-chelating drug deferoxamine (DF). Recent experimental evidence suggests that DF may also be useful in modifying disease conditions unrelated to iron overload by preventing the formation of free radicals, the powerful final effectors of tissue damage resulting from the respiratory burst of granulocytes and macrophages participating in the inflammatory response. Although much experimental work is still needed, this novel approach in iron-chelating therapy may have far-reaching implications in the management of autoimmune disease, adult respiratory distress syndrome, and organ transplantation. The poor intestinal absorption of DF, its almost prohibitive price, and short duration of action underline the need for new, orally effective iron chelators. A number of very promising orally effective drugs have been identified in recent years, such as the polyanionic amines, aryl hydrazones, and hydroxypyridones. Further development for clinical use of this new generation of iron-chelating drugs is a major challenge for future research.
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Affiliation(s)
- C Hershko
- Department of Medicine, Shaare Zedek Medical Center, Jerusalem, Israel
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37
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38
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Breithaupt H, Heckers H, Pralle H, Guttmann W, Bleyl H, Graef V, Jundt G. High dosage desferrioxamine therapy in a female patient with acquired aplastic anaemia and transfusion siderosis. BLUT 1986; 52:211-9. [PMID: 3634632 DOI: 10.1007/bf00321080] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
A 32 year old woman with severe aplastic anaemia required frequent transfusions and consequently developed hyperferrioxaemia (54 microMol/l) and hyperferritinaemia (1,700 ng/ml). For the treatment of transfusion siderosis she was given 18 high dose courses each comprising 35 g of desferrioxamine. Because of pre-existing thrombocytopenia (platelet count 5 X 10(9)/l) the iron chelating agent was given by continuous intravenous infusion over 3 1/2 days. High dose desferrioxamine had to be abandoned because of severe bone pain. The desferrioxamine infusions achieved a negative iron balance, iron loss after each infusion being 100 to 200 mg in the urine and 400 mg in the faeces. Serum iron and ferritin concentrations fell almost to normal. This report shows that faecal iron excretion must be taken into account in assessing the balance of iron input and output during desferrioxamine treatment.
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39
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Davies SC, Marcus RE, Hungerford JL, Miller MH, Arden GB, Huehns ER. Ocular toxicity of high-dose intravenous desferrioxamine. Lancet 1983; 2:181-4. [PMID: 6135026 DOI: 10.1016/s0140-6736(83)90170-8] [Citation(s) in RCA: 194] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Desferrioxamine was given intravenously, at higher doses than previously reported, to counter the effects of transfusion-induced iron overload in four patients with beta thalassaemia major. In two of them retinal abnormalities developed, presenting with night blindness and field defects, which improved on withdrawal of the drug.
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