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Early treatment with deferoxamine limits myocardial ischemic/reperfusion injury.

Oxygen-derived free radicals (the superoxide anion O2- and hydroxyl radical.OH) have been implicated in myocardial injury associated with coronary artery occlusion followed by reperfusion. Transition metals (such as iron or copper) are needed to catalyze the formation of the .OH radical and subsequent .OH-mediated lipid peroxidation, yet the role of these transition metals in the pathogenesis of myocyte necrosis remains undefined. To address this issue, 21 dogs underwent 2 h of coronary artery occlusion and 4 h of reperfusion. Each animal was randomly assigned into 1 of 3 treatment groups: 7 received the iron chelator deferoxamine beginning 30 min preocclusion, 7 received deferoxamine beginning 5 min prior to reperfusion, while 7 dogs served as saline controls. Deferoxamine effectively chelated free iron in both treatment groups (total urine iron content averaged 42 +/- 16, 662 +/- 177 and 803 +/- 2.5 micrograms in control, pretreated, and deferoxamine at reperfusion groups respectively; p less than 0.05), but had no significant effect on in vivo area at risk (AR), hemodynamic parameters, collateral blood flow during occlusion, or myocardial blood flow following reperfusion. Area of necrosis (AN) in dogs pretreated with deferoxamine (34.6 +/- 3.7% of the AR; p less than 0.05) was significantly smaller than that observed in the saline control group (55.4 +/- 4.7% of the AR). Deferoxamine administered at the time of reperfusion, however, had no significant effect on infarct size (AN/AR = 54.3 +/- 8.7%, p = NS vs. controls). Thus, early treatment with the iron chelator deferoxamine acutely reduced the extent of myocyte necrosis produced by 2 h of transient coronary artery occlusion in the canine model.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Binding of deferoxamine to asbestos fibers in vitro and in vivo.

We studied the binding of tritium-labeled deferoxamine, a strong iron chelator, to crocidolite asbestos fibers in vitro and in vivo. In aqueous suspension of asbestos, deferoxamine binding was rapid and strong, suggesting specific binding to iron. For the in vivo experiments, diffusion chambers containing native asbestos fibers or deferoxamine-washed asbestos were implanted in the peritoneal cavities of mice. Five days after parenteral injection of tritiated deferoxamine chambers were removed and the asbestos counted. More than twice as much label (2206 +/- 348 c.p.m./100 mg asbestos) was bound to the native asbestos as compared to the deferoxamine-washed asbestos (1080 +/- 201 c.p.m./100 mg asbestos), suggesting specific binding in vivo. Since deferoxamine can inhibit asbestos toxicity in vitro, these experiments suggest the feasibility of testing whether deferoxamine can prevent asbestos-related disease in vivo.

Animals↗

Novel uses of deferoxamine.

Deferoxamine has been extensively used as chelation therapy in iron-overloaded states. Recently, some investigators have explored the potential usefulness of deferoxamine as an antiproliferative, antiinflammatory, and immunosuppressive agent. The studies of deferoxamine have indicated that the drug blocks DNA synthesis by inhibition of ribonucleotide reductase. Deferoxamine has also shown antiinflammatory properties, possibly by inhibition of polymorphonuclear neutrophil function. Analysis of possible antiinflammatory effects of deferoxamine has been complicated by concomitant immunosuppressive effects of the drug. Deferoxamine inhibits T lymphocyte proliferation, both by ribonucleotide reductase inhibition and by preventing the expression of interleukin 2 receptor-alpha chain. The use of iron-chelating agents in non-iron-overloaded patients carries the risk of neurologic, metabolic, and infectious complications. The clinical usefulness of deferoxamine in these novel applications will require careful study of both efficacy and any toxic effects.

Animals↗

Auditory and visual toxicity during deferoxamine therapy in transfusion-dependent patients.

Deferoxamine is a chelating agent that has extended the life expectancy of patients with thalassemia. In the 1980s, many investigators reported otologic and visual toxicity caused by deferoxamine. In July 1999 and 2 years later, the authors performed audiologic and ophthalmologic assessments in 30 transfusion-dependent patients receiving deferoxamine therapy (40-50 mg/kg per dose, subcutaneously for 8-10 hours, 4-7 days per week). In 1999, six patients (20%) had deferoxamine-related hearing impairment (>25 dB), all at high frequencies. Because the authors believed the benefits of chelation therapy outweighed the risk of ototoxicity, the dose of deferoxamine was not reduced. Two years later, the hearing impairment had not progressed in any of the patients. There was no association between ototoxicity and ferritin level. No patients had abnormalities of visual acuity or funduscopy in either 1999 or 2001. Based on this experience, deferoxamine at doses lower than 50 mg/kg/d was safe for the eyes and slightly toxic to the ears. The ototoxicity probably relates to individual susceptibility. Regular monitoring of auditory function and close follow-up of abnormal findings are recommended. According to this limited experience, reducing the dose or withdrawing deferoxamine might not be necessary if the hearing loss is stable in the face of ferritin levels above 2,000 ng/mL. Because of the relatively small patient numbers, more data are needed to confirm these conclusions.

Acoustic Impedance Tests↗

Delayed administration of deferoxamine reduces brain damage and promotes functional recovery after transient focal cerebral ischemia in the rat.

The mechanisms underlying functional recovery after stroke are poorly understood. Brain-adaptive responses to the hypoxic stress elicited by ischemia could contribute to these mechanisms. Indeed, hypoxia-inducible factor-1 (HIF-1), one of the main transcriptional factors regulated by oxygen level, increases the expression of several beneficial genes such as erythropoietin, glucose transporter-1 and vascular endothelial growth factor. In order to strengthen the expression of these hypoxia-inducible factors, we administered deferoxamine, an iron chelator known to stabilize HIF-1alpha protein expression, and examined its effects on the functional deficits induced by ischemia. Anesthetized Sprague-Dawley rats were subjected to 60 min of intraluminal occlusion of the middle cerebral artery. Chronic deferoxamine treatment (300 mg/kg, s.c.), or its vehicle, started 24 h after ischemia and was continued bi-weekly until the animals were killed. Sensorimotor deficits were periodically assessed over 2 months, and at this end point, the lesion volume was determined by histology. Treatment with deferoxamine significantly decreased the size of brain damage (-28%) after ischemia and improved behavioral recovery. Indeed, neurological score and sensorimotor performances in the adhesive removal test recovered earlier in the deferoxamine-treated animals. Moreover, the long-lasting skilled forepaw reaching deficits were attenuated by deferoxamine. Although an antioxidant effect of deferoxamine cannot be excluded, the hypothesis that its beneficial effects could be mediated by an increase in HIF-1 target genes merits further investigations. Our data suggest that delayed administration of deferoxamine could represent an interesting therapeutical approach to treat focal cerebral ischemia.

Animals↗

The effect of deferoxamine on bleomycin-induced lung fibrosis in the hamster.

Bleomycin is a commonly used antineoplastic compound that can produce a dose- and time-dependent pneumonitis and fibrosis in humans. The mechanism of bleomycin-induced fibrosis is not known. However, current data suggest that the production of oxygen radicals by way of a ferrous ion-molecular oxygen mechanism might be related to the pulmonary fibrosis. Therefore, we evaluated the possibility that parenterally administered deferoxamine, an iron chelating compound, could modulate the morphologic and biochemical estimates of bleomycin-induced lung fibrosis in hamsters. Deferoxamine pretreatment and daily injection for 21 days after intratracheally administered bleomycin resulted in a 33% reduction in lung collagen accumulation compared with that after bleomycin treatment alone. However, fibrosis was still present in the bleomycin-deferoxamine group; the animals showed a 142 and 150% increase in lung collagen compared with that in saline- and deferoxamine-treated control animals, respectively. Morphologic estimates of the severity of fibrosis in the bleomycin-deferoxamine treatment group were reduced when compared with the bleomycin treatment group alone, but was increased compared with saline- and saline-deferoxamine-treated control animals. These data indicate that deferoxamine treatment reduces the severity of bleomycin-induced pulmonary fibrosis in hamsters. The mechanism might be by the prevention of iron-catalyzed, free-radical formation.

Animals↗

Influence of iron status in the response to the deferoxamine test.

The study presented here was carried out to evaluate the possible relationship between serum iron and iron transferrin saturation with the response to the deferoxamine test in 86 chronic renal failure patients undergoing hemodialysis. The deferoxamine test was performed as a diagnostic tool for aluminum intoxication. Basal serum aluminum levels correlated with: (1) serum aluminum levels after the infusion of deferoxamine (r = 0.45; P < 0.05); (2) serum iron levels (r = -0.26; P < 0.05), and; (3) iron transferrin saturation (r = -0.33; P < 0.05). The increase in serum aluminum levels after deferoxamine administration (DAI) showed a negative relationship with serum iron levels (r = -0.23; P < 0.05) and iron transferrin saturation (r = -0.26; P < 0.05). The correlations improved when analysis of this study included only those patients with high serum iron levels or high iron transferrin saturation (r = -0.55). Patients with low probability of having aluminum overload (serum iron levels < 40 micrograms/L and DAI < 150 micrograms/L) had significantly higher values of serum iron, iron transferrin saturation, and serum ferritin levels compared with those patients with a high probability of having aluminum overload (serum aluminum levels > 40 micrograms/L and DAI > 150 micrograms/L). The study presented here suggests that patients who have indicators of iron repletion would tend to have lower increases in serum aluminum levels after the challenge with deferoxamine and presumably a higher incidence of false negative results with the deferoxamine test. These findings indicate that iron measurements must be always taken into account when interpreting the deferoxamine test.

Aluminum↗

Inhibitory effect of deferoxamine mesylate and low iron diet on the 13762NF rat mammary adenocarcinoma.

The iron chelator deferoxamine mesylate has been shown to inhibit the growth of a variety of human malignant cell lines and the rat 13762NF mammary adenocarcinoma cell line. In vivo studies in mice have also demonstrated that an iron deficiency induced by either feeding a low iron diet or injecting the iron chelator deferoxamine mesylate decreases tumor growth. In this study Fisher rats were transplanted with the 13762NF mammary adenocarcinoma and divided into four groups: normal diet, normal diet plus deferoxamine mesylate treatment, low iron diet and low iron diet plus deferoxamine mesylate treatment. The measurements of tumor size and body weight were recorded weekly. We found that treatment with either deferoxamine mesylate or a low iron diet decreased rat tumor growth, but the greatest inhibitory effect on tumor growth occurred when the rats were treated with deferoxamine mesylate injections plus fed a low iron diet. These treatments did not significantly inhibit the weight gain of the rats. At the end of the experiments measurement of serum iron proved that these treatments caused iron deficiency, but there was no significant treatment related alteration in blood hematocrit. We therefore concluded that deferoxamine mesylate may be a useful chemotherapeutic agent in the treatment of breast cancer, when used in combination with standard chemotherapeutic regiments or with other agents that interfere with iron metabolism, and further that the restricting of iron intake should be considered when planning chemotherapy for all cancer patients.

Adenocarcinoma↗

Iron chelation therapy and lung transplantation. Effects of deferoxamine on lung preservation in canine single lung transplantation.

Reperfusion injury is a limiting factor in lung transplantation. Deferoxamine is an iron chelator that inhibits the formation of oxygen-derived free radicals. We investigated the effects of deferoxamine on posttransplantation lung function in a canine model of single lung transplantation. Twelve dogs underwent left lung transplantation after 20- to 24-hour hypothermic storage in a modified Euro-Collins solution. In six experiments donor and recipient received a 10 mg/kg dose of deferoxamine before harvest and transplantation, and 10 mg/kg was added to the preservation solution. Arterial oxygen tension, alveolar-arterial oxygen difference, pulmonary vascular resistance, and dynamic lung compliance were measured. Data were recorded for 6 hours after ligation of the native pulmonary artery. At the end of the study the mean arterial oxygen tension was 175.1 mm Hg for the deferoxamine treated group versus 71.1 mm Hg for the control group (p less than 0.001), and the alveolar-arterial oxygen difference was less in the deferoxamine-treated group: 502.3 versus 606.0 mm Hg (p less than 0.001). The mean pulmonary vascular resistance was lower throughout the study, and after 6 hours it was 455.1 dynes/sec/cm(-5) in the deferoxamine-treated group versus 663.7 dynes/sec/cm(-5) in the control group (p less than 0.035). Compliance was similar in both groups. We conclude that deferoxamine improves lung preservation and early posttransplantation function in canine single lung transplantation.

Animals↗

Deferiprone versus deferoxamine in patients with thalassemia major: a randomized clinical trial.

Deferiprone has been suggested as an effective oral chelation therapy for thalassemia major. To assess its clinical efficacy, we compared deferiprone with deferoxamine in a large multicenter randomized clinical trial. One-hundred forty-four consecutive patients with thalassemia major and serum ferritin between 1500 and 3000 ng/ml were randomly assigned to deferiprone (75 mg/kg/day) (n = 71) or deferoxamine (50 mg/kg/day) (n = 73) for 1 year. The main measure of efficacy was the reduction of serum ferritin. Liver and heart iron contents were assessed by magnetic resonance. Liver iron content and fibrosis stage variations were assessed on liver biopsy by the Ishak score in all patients willing to undergo liver biopsy before and after treatment. The mean serum ferritin reduction was 222 +/- 783 ng/ml in the deferiprone and 232 +/- 619 ng/ml in the deferoxamine group (P = 0.81). No difference in the reduction of liver and heart iron content was found by magnetic resonance between the two groups. Thirty-six patients accepted to undergo repeat liver biopsy: 21 in the deferiprone and 15 in the deferoxamine group. Their mean reduction of liver iron content was 1022 +/- 3511 microg/g of dry liver and 350 +/- 524, respectively (P = 0.4). No difference in variation of the Ishak fibrosis stage was observed between the two groups. Treatment was discontinued because of reversible side effects in 5 patients in the deferiprone group (3 hypertransamin/asemia and 2 leukocytopenia) and in none in the deferoxamine group. These findings suggest that deferiprone may be as effective as deferoxamine in the treatment of thalassemia major with few mild and reversible side effects.

Adolescent↗

In vitro tumor growth inhibition by bispecific antibodies to human transferrin receptor and tumor-associated antigens is augmented by the iron chelator deferoxamine.

Previously, a panel of mouse monoclonal antibodies (mAbs) to several tumor-associated antigens was chemically crosslinked to an IgG1 anti-human transferrin receptor antibody, 454A12. We called this new class of bispecific antibodies (BmAbs) "antigen forks" and showed that these antigen forks inhibited but did not completely prevent tumor cell growth. We speculated that the conjugates acted by heterologously crosslinking two antigens in a manner that interfered with the functions of one or both. The most effective BmAbs all shared one specificity for the human transferrin receptor. A monoclonal antibody to this receptor has been shown by others to reduce tumor cell growth when used with the iron chelator deferoxamine. When we combined our antigen forks with deferoxamine, two of five BmAbs synergized with deferoxamine to arrest tumor cell count at or below input levels. The most effective BmAbs were 317G5/454A12 (3/4) and 520C9/454A12 (5/4). mAb 317G5 recognizes a 42-kDa tumor-associated glycoprotein, and mAb 520C9 recognizes the c-erbB-2 protooncogene product. BmAb 3/4 was most effective against colorectal cancer cell line HT-29, and BmAb 5/4 was most effective against breast cancer cell line SK-BR-3. When deferoxamine and BmAb were replaced by fresh medium after a 6- or 7-day treatment period, no regrowth of tumor cells was observed during the next 4 days, although regrowth was seen if either deferoxamine or BmAb was used alone. Our results show that BmAbs with specificities for transferrin receptor and certain tumor-associated antigens effectively inhibit tumor growth in vitro. When used in combination with deferoxamine, such BmAbs may have therapeutic potential for the treatment of cancer.

Adjuvants, Immunologic↗

Deferoxamine reduces CSF free iron levels following intracerebral hemorrhage.

Iron overload occurs in brain after intracerebral hemorrhage (ICH). Deferoxamine, an iron chelator, attenuates perihematomal edema and oxidative stress in brain after ICH. We investigated the effects of deferoxamine on cerebrospinal fluid (CSF) free iron and brain total iron following ICH. Rats received an infusion of 100-microL autologous whole blood into the right basal ganglia, then were treated with either deferoxamine (100 mg/kg, i.p., administered 2 hours after ICH and then at 12-hour intervals for up to 7 days) or vehicle. The rats were killed at different time points from 1 to 28 days for measurement of free and total iron. Behavioral tests were also performed. Free iron levels in normal rat CSF were very low (1.1 +/- 0.4 micromol). After ICH, CSF free iron levels were increased at all time points. Levels of brain total iron were also increased after ICH (p < 0.05). Deferoxamine given 2 hours after ICH reduced free iron in CSF at all time points. Deferoxamine also reduced ICH-induced neurological deficits (p < 0.05), but did not reduce total brain iron. In conclusion, CSF free iron levels increase after ICH and do not clear for at least 28 days. Deferoxamine reduces free iron levels and improves functional outcome in the rat, indicating that it may be a potential therapeutic agent for ICH patients.

Animals↗

Impairment of nucleotide metabolism by iron-chelating deferoxamine.

The effect of deferoxamine on nucleotide metabolism in HL-60 leukemic cells was studied to explore the mechanism of its antiproliferation activity. It was found that in intact cells deferoxamine markedly inhibited the ribonucleotide reduction and incorporation of bases (adenine, hypoxanthine), ribonucleosides (inosine, guanosine) and deoxyribonucleosides (thymidine, deoxyadenosine, deoxyguanosine) into nucleic acids. Although deferoxamine did not inhibit thymidine and uridine incorporation into free nucleotides, inhibition of hypoxanthine and adenine incorporation into nucleotides as well as inhibition of nucleotide biosynthesis de novo was found. Nucleotide catabolism, protein synthesis, and intracellular levels of ribonucleotides were not affected significantly by deferoxamine. These results showed that deferoxamine selectively affects several specific reactions of nucleotide metabolism. Inhibition of ribonucleotide reduction, inhibition of ribonucleotide and deoxyribonucleotide incorporation into nucleic acids, as well as inhibition of purine biosynthesis, may alter significantly cellular physiology and, therefore, contribute significantly to the antiproliferative activity of deferoxamine.

Cell Division↗

Prolonged survival in patients with beta-thalassemia major treated with deferoxamine.

To determine whether survival of patients with beta-thalassemia major has been prolonged by management that utilizes hypertransfusion and chelation with deferoxamine, we analyzed longevity by the Kaplan-Meier product-limit method. Group 1 patients (n = 71) followed between 1960 and 1976 with a low-transfusion regimen (pretransfusion hemoglobin level 7 to 8 gm/dl) and no chelation had an estimated median age of survival of 17.4 years, whereas it was 31.0 years for group 2 subjects (n = 80), who began hypertransfusion between 1976 and 1978 (pretransfusion hemoglobin level 10.5 to 11.5 gm/dl) and chelation with deferoxamine (20 to 60 mg/kg per day) (p less than 0.0001). For 70 patients who were treated with hypertransfusion and deferoxamine, we had data to calculate the ratio of total milligrams of transfusional iron to cumulative grams of deferoxamine. The 24 patients who died had a total iron burden of greater than 1.05 gm/kg; the ratio for them exceeded 31. These patients were characterized by poor compliance with chelation or by late start of therapy, with inability to receive enough deferoxamine before death. Death was preceded by arrhythmia requiring therapy in all but one, and by cardiac failure in all. Of 41 similarly iron-loaded survivors, 33 had a ratio of less than 31; only three had an arrhythmia, and five had cardiac failure. We conclude that treatment with deferoxamine, when used in amounts proportional to iron burden, delayed cardiac complications and improved longevity.

Adolescent↗

Iron chelation therapy with deferoxamine in Cooley anemia.

The iron-chelating agent, deferoxamine, was studied in 16 patients with thalassemia major. Urinary excretion of iron in response to 0.75 gm of deferoxamine, intramuscularly, ranged from 2.2 to 44.8 mg Fe/24 hours. In response to a subcutaneous infusion of 1.5 gm deferoxamine for 18 hours, iron excretion increased by an average of 240%. The intravenous infusion of large doses of deferoxamine for 18 hours resulted in the highest rate of iron excretion, as much as 447.5 mg Fe/24 hours in response to 16 gm of deferoxamine. Administration of vitamin C increased chelation-induced excretion of iron in most patients more than five years of age. Preliminary evidence suggests that further iron accumulation can be prevented and excessive iron stores can be depleted by the intramuscular, subcutaneous, or intravenous administration of deferoxamine.

Adolescent↗

Effect of deferoxamine and allopurinol on non-protein-bound iron concentrations in plasma and cortical brain tissue of newborn lambs following hypoxia-ischemia.

Reduction of non-protein-bound iron (NPBI) using iron chelators may attenuate hypoxia-ischemia-induced reperfusion injury of the brain. This study investigated whether administration of low-dose deferoxamine and allopurinol, both having NPBI-chelating properties, reduced hypoxia-ischemia-induced NPBI formation in plasma effluent from the brain and in cerebral cortical tissue. Twenty-one newborn lambs underwent severe hypoxia-ischemia. Upon reperfusion and reoxygenation the lambs received either a placebo (n = 7), or deferoxamine 2.5 mg/kg (n = 7) or allopurinol 20 mg/kg (n = 7). The post-hypoxic-ischemic NPBI levels in plasma were significantly lower after deferoxamine but not after allopurinol as compared to placebo-treated lambs. Cortical NPBI levels in both deferoxamine and allopurinol-treated lambs were significantly lower than NPBI levels in placebo-treated lambs. We conclude that deferoxamine effectively lowers NPBI in plasma effluent from the brain, and that both, deferoxamine and allopurinol, lower NPBI in cortical brain tissue.

Allopurinol↗

Comparison between deferoxamine and deferiprone (L1) in iron-loaded thalassemia patients.

INTRODUCTION: Iron-chelating therapy with deferoxamine in patients with thalassemia major has dramatically improved the prognosis of this disease. However, the limitations of this treatment have stimulated the design of alternative orally active iron chelators. OBJECTIVE: To compare the effectiveness and safety of, and compliance with, oral deferiprone (L1), and deferoxamine, in thalassemia major patients. METHODS: All patients were followed up in one center in Lebanon. Sixteen patients were on L1 (75 mg/kg/d), and 40 patients on subcutaneous deferoxamine (20-50 mg/kg/d). Serum ferritin level, urinary iron excretion (UIE) and side effects were monitored over a two year period. RESULTS: Patients on L1 had an initial serum ferritin concentration of 3663+/-566 microg/l (mean+/-SEM), that dropped to 2599+/-314 at 6 months (p<0.02; paired t-test), and stabilised at that level over the 24 months follow up. Patients on deferoxamine had an initial mean serum ferritin concentration of 3480+/-417 (NS compared to the L1 group), which dropped gradually to 3143+/-417 (p<0.05) and 2819+/-292 (p<0.02) at 6 and 24 months, respectively. The most common adverse reactions associated with L1 were arthralgia and nausea, but they did not necessitate stopping the drug. CONCLUSION: L1 had comparable efficacy as deferoxamine with minimal side effects and better compliance. Provided long term side effects are not encountered, L1 seems to be a valuable alternative iron chelator for patients unable or unwilling to use deferoxamine effectively.

Administration, Oral↗

Suppression of deferoxamine mesylate treatment-induced side effects by coadministration of isoniazid in a patient with Alzheimer's disease subject to aluminum removal by ionspecific chelation.

Deferoxamine treatment may produce serious side effects that can be eliminated by modification of treatment and by control of deferoxamine metabolism. A patient suffering from dementia of the Alzheimer type with normal liver and kidney function who was treated with deferoxamine initially tolerated a dose of 7 mg/kg deferoxamine mesylate injected intramuscularly twice a day for a total of 5 days a week. After several months nausea and weight loss gradually developed in the patient that could be controlled initially by dose reduction, leading to levels inappropriate for aluminum chelation. HPLC analysis of blood and urine revealed several metabolites including, as a major component, a plasma monoamine oxidase (MAO) catalyzed end product MFO1. Coadministration of isoniazid, a plasma MAO inhibitor, with deferoxamine resulted in reduction of MFO1 from 81% to 8% accompanied by increases in the amounts of metabolite 2 (MFO2) from 2% to 24% and unmetabolized deferoxamine from 17% to 68% after 6 months of treatment. The side effects subsided, the patient regained weight, and treatment could be continued.

Aluminum↗