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PubMed1989

Kinetics and efficacy of deferoxamine in iron-overloaded hemodialysis patients.

We evaluated the kinetics and efficacy of deferoxamine (DFO) therapy in iron-overloaded hemodialysis patients. Concentrations of DFO and its chelated product, feroxamine (Fx), were assessed following single-dose DFO administration in twelve patients, and during chronic therapy over one year's time in eight, similarly iron-overloaded dialysis patients. A functional assay which relies on measurements of iron and iron binding capacity for the determination of Fx and DFO, respectively, was corroborated with liquid chromatographic techniques. Half-life measurements were also corroborated with tracer doses of 14C-DFO and 59Fe-feroxamine. Intradialytic DFO half-life (2.3 +/- 1.1 h) was considerably less than interdialytic half-life (26 +/- 1 hr). Unbound DFO was found to persist throughout the interdialytic period. Calculation of the percent saturation of the DFO dose indicated that only 30% of a given dose is chelated. The amount of iron removed dialytically was approximately 13.1 +/- 2.7 mg per dialysis session. Chronic DFO administration was also shown to enhance gastrointestinal iron excretion threefold. However, ferritin levels decreased by only 25% after one year of thrice-weekly DFO therapy. We conclude that DFO therapy for iron-overloaded hemodialysis patients is optimized by its administration interdialytically, and results in slow removal of iron, via both dialytic and gastrointestinal routes.

Adult↗
PubMed1994

Deferoxamine augments growth and pathogenicity of Rhizopus, while hydroxypyridinone chelators have no effect.

Deferoxamine (DFO), when used in dialysis patients, is a well recognized risk factor for the development of mucormycosis caused by Rhizopus. This study compares, both in vivo and in vitro, the effects produced on Rhizopus by DFO and by two chelators of the hydroxypyridinone class, L1 and CP94. Experimental systemic mucormycosis was induced in the guinea pig by an i.v. injection of two different strains of Rhizopus: R. microsporus and R. arrhizus. Concomitant i.p. administration of DFO for four days shortened animal survival (P < 0.05), whereas concomitant administration of either L1 or CP94 did not. In vitro radioiron uptake by R. microsporus was 100-fold higher from the 55ferric complex of DFO than of L1 or CP94. In vitro fungal growth was stimulated sevenfold by the ferric complex of DFO (P < 0.0001) but not significantly by the ferric complex of either L1 or CP94. These results indicate that the ferric complex of DFO but not that of L1 or CP94 specifically stimulates both the iron uptake and the growth of Rhizopus. They suggest that the risk of developing mucormycosis should be minimal with L1 or CP94, as opposed to DFO.

Animals↗
PubMed2001

Mitochondrial involvement in cocaine-treated rat hepatocytes: effect of N-acetylcysteine and deferoxamine.

The cytotoxicity of cocaine (0 - 1000 microM), was studied on parameters related to the mitochondrial role and the cascade of events that lead to apoptosis in hepatocyte cultures from phenobarbitone (PB) pretreated rats. Cytotoxicity was dose-dependent and LDH leakage was significantly enhanced above 100 microM cocaine. Apoptosis was visualized by DNA fragmentation on agarose gel, and appeared at 50 and 100 microM cocaine. Cocaine induced biphasic changes in mitochondrial transmembrane potential and significantly increased the mitochondrial release of cytochrome c, the caspase-3 like DEVDase activity and the level of 20 kDa subunit, a product of pro-caspase-3 cleavage. The protective effect of N-acetylcysteine (NAC) and deferoxamine (DFO) on all these parameters confirmed the involvement of oxygen radicals in cocaine-induced necrosis/apoptosis. We conclude: first, that the biphasic changes recorded in mitochondrial inner membrane potential by the effect of cocaine, were parallel to apoptosis; second, that caspase-3 activity and cleavage to it p20 subunit increased sharply in parallel to the translocation of cytochrome c from mitochondria to cytosol; and third, that the antioxidants, NAC or DFO exerted a noticeable protective role in counteracting the cytotoxicity of cocaine, these effects being more pronounced in the case of DFO than NAC. These findings demonstrate that cocaine cytotoxicity involves mitochondrial damage.

Acetylcysteine↗
PubMed2004

Effectiveness and safety of combined iron-chelation therapy with deferoxamine and deferiprone.

INTRODUCTION: The purpose of our study was to evaluate the effectiveness and safety of combined therapy with deferoxamine (DFO) and deferiprone (DFP) in patients with beta-thalassemia major and increased serum ferritin. PATIENTS AND METHODS: Our study was performed in 36 patients with beta-thalassemia major. DFP was administered orally in a total daily dose of 60 mg/kg for 6 days per week and DFO was administered subcutaneously in a total daily dose of 40-50 mg/kg for 4-6 days per week. The efficacy of combined treatment was assessed by measurements of serum ferritin and 24-h urine iron excretion levels. RESULTS: Out of the 36 patients, 11 discontinued DFO after a mean of 4 months; however, 25 patients, who continued to receive the combined therapy showed a very satisfactory compliance. After a mean of 13.5 months, their mean serum ferritin levels reduced from 2637 + 1292 to 1580 + 1024 ng/ml (P = 0.002) and their mean urinary iron excretion elevated from 0.41 + 0.27 to 0.76 +0.49 mg/24h (P = 0.003). The observed side effects were gastrointestinal disorders,elevations in liver enzymes, mild neutropenia, joint symptoms, taste disorders, dizziness and fatigue. CONCLUSIONS: The results of this study show that combined iron-chelation therapy with DFO and DFP results in satisfactory reduction of serum ferritin with no significant toxicity.

Administration, Oral↗
PubMed2001

Cutaneous hyperpigmentation following venous sclerotherapy treated with deferoxamine mesylate.

BACKGROUND: Cutaneous hyperpigmentation after venous sclerotherapy is an adverse sequelae of difficult management. OBJECTIVE: To evaluate the degree of depigmentation with the use of deferoxamine mesylate (DM) in patients with postsclerotherapy hyperpigmentation treated with polydocanol (POL) for telangiectasias and reticular veins (0.2-5 mm diameter) and varicose veins (5-8 mm diameter). METHODS: The experimental group of 36 female patients (mean age 37 years) was divided in two groups. Group I consisted of 30 patients who were treated with POL at 0.25-0.50% concentration for telangiectasias and reticular veins. Group II consisted of six patients with prolonged postsclerotherapy hyperpigmentation (more than 6 months after treatment) in varicose veins that had been treated with POL at 1.5% concentration each week. Groups I and II were injected with DM 500 mg subcutaneously once a week until 81-100% depigmentation was reached. In group I, DM was injected at the time of sclerotherapy. These groups were compared to their respective control groups with similar conditions but allowing spontaneous depigmentation without DM. Evaluation was undertaken clinically and photographically, and the number of days required to reach the desired depigmentation of 81-100% was determined. RESULTS: When DM was used, depigmentation of 81-100% was observed in group I at 27 days, and for group II in 46 days. In each control group, similar depigmentation was seen at 150 +/- 19 and 255 +/- 11 days, respectively. Comparing results, there was a reduction in the time to depigmentation of 82% for each group (P <.0001). CONCLUSION: The weekly subcutaneous administration of DM 500 mg reduces the time to depigmentation by 82% in patients with postsclerotherapy cutaneous hyperpigmentation treated for telangiectasias and reticular veins and prolonged postsclerotherapy hyperpigmentation in varicose veins. In this study we could not explain why such variability exists in the length of time to spontaneous depigmentation.

Adult↗
PubMed1992

[Rhinocerebral mucormycosis during deferoxamine therapy].

A 24-year-old woman had been in full remission of an acute myeloid leukaemia since 1988, but she required regular erythrocyte and platelet transfusions for pancytopenia. To counteract a progressive siderophilia due to the transfusions (ferritin levels of about 10,000 ng/ml) deferoxamine was intermittently given intravenously (5 g after each transfusion). Seven months after the start of this treatment the patient was hospitalized because of severe left-sided facial pain as well as reddening and swelling in the periorbital region. As maxillary and frontal sinusitis was suspected, antibiotics were administered (at first three times daily 2.2 g amoxicillin and clavulanic acid, then two times daily 300 mg rifampicin and 200 mg ciprofloxacin). Nonetheless, orbital phlegmon developed within a few days with protrusion and blindness of the left eye necessitating a decompression operation. Material obtained at operation revealed rhinocerebral mucormycosis. After 3 weeks of antimycotic treatment with both amphotericin B (1 mg/kg.d) and flucytosine (150 mg/kg.d) the mucormycosis healed without the necessity of extensive and disfiguring removal of necrotic tissue. But the blindness in the left eye, caused by occlusion of the central artery, was irreversible.

Adult↗
PubMed1986

[Longitudinal growth of patients with homozygote beta-thalassemia during continuous subcutaneous infusion of deferoxamine].

Subcutaneous continuous infusions of deferoxamine were administered to 28 children with thalassaemia major. Longitudinal growth beyond the eleventh year was favourably influenced. The normal growth spurt during puberty was not demonstrable in six patients (three boys and three girls) during their puberty. Taking into account standard height allowing for parents' height, prospective final height and ethnic origin, the treatment favourably influenced longitudinal growth in 26 of the 28 children.

Age Determination by Skeleton↗
PubMed1985

[Continuous subcutaneous deferoxamine treatment in thalassemia major. Decrease of hemosiderosis and improvement of liver function].

Liver function during continuous subcutaneous deferoxamine therapy was investigated in 29 patients with homozygotic beta-thalassaemia. Average duration of treatment was 26 months (range 8-51 months). A decrease in haemosiderosis and an improvement in liver function was observed in 27 patients: Mean liver density, determined by computed tomography, decreased from 98 to 84 HU, mean serum ferritin concentration fell from 8028 to 3661 ng/ml, mean serum GOT activity from 44 to 13 U/l and GPT from 51 to 16 U/l. Mean cholinesterase activity, reflecting the improved synthetic activity of the liver, increased from 4063 to 4530 U/l.

Adolescent↗
PubMed1984

[Deferoxamine in hemosiderosis. Fecal iron excretion during continuous subcutaneous infusion].

Faecal iron excretion during continuous subcutaneous deferoxamine infusion was measured by flameless atom-absorption spectral photometry in 21 patients with homozygous ss-thalassaemia and one patient with Blackfan-Diamond anaemia. Taking into account faecal and urinary iron excretion, more iron was eliminated than was taken up during transfusion and by intestinal absorption. Urine contained 37.9%, faeces 62.1% of the amount of iron eliminated.

Adolescent↗
PubMed2001

Exploring the "iron shuttle" hypothesis in chelation therapy: effects of combined deferoxamine and deferiprone treatment in hypertransfused rats with labeled iron stores and in iron-loaded rat heart cells in culture.

Although iron chelation therapy results in a significant improvement in well-being and life expectancy of thalassemic patients with transfusional iron overload, failure to achieve these goals in a substantial proportion of patients underlines the need for improved methods of treatment. In the present studies we used selective radioactive iron probes of hepatocellular and reticuloendothelial (RE) iron stores in hypertransfused rats and iron-loaded heart cells to compare the source of iron chelated in vivo by deferoxamine (DFO) or by deferiprone (L1) and its mode of excretion, to examine the ability of DFO and L1 to remove iron directly from iron-loaded myocardial cells, and to examine the mechanism of their combined interaction through a possible additive or synergistic effect. Our results indicate that L1 given orally is 1.6 to 1.9 times more effective in rats, on a weight-per-weight basis, than parenteral DFO in promoting the excretion of storage iron from parenchymal iron stores but shows no advantage over DFO in promoting RE iron excretion. Simultaneous administration of DFO and L1 results in an increase in chelating effect that is additive but not synergistic. The magnitude of this additive effect is identical to an increase in the equivalent (weight or molar) dose of DFO alone rather than the sum of the separate effects of L1 and DFO. This finding is most probably the result of a transfer of chelated iron from L1 to DFO. These observations may have practical implications for current efforts to design better therapeutic strategies for the management of transfusional iron overload.

Animals↗
PubMed2002

The iron-loaded gerbil model revisited: effects of deferoxamine and deferiprone treatment.

Although the beneficial effects of deferoxamine (DFO) on iron-associated morbidity and mortality are well documented, the role of deferiprone (L1) in the management of transfusional iron overload is controversial. This debate involves not only the question of efficacy but also of safety, with particular emphasis on the risk of a paradoxical aggravation of iron toxicity by L1. We used the iron-loaded gerbil model introduced by Carthew et al to compare the chelating efficacy of L1, DFO, or both in two gerbil strains treated by means of weekly iron-dextran injections: Psammomys obesus and pathogen-free Mongolian gerbils (Meriones unguiculatus). The difference between the high mortality and advanced hepatocellular necrosis observed in iron-loaded P obesus and the absence of mortality and limited morbidity encountered in pathogen-free Mongolian gerbils is most likely explained by the prevention of coincidental laboratory infections in the latter group. Iron-chelating treatment in all experimental groups resulted in a significant decrease in hepatic iron concentrations and normalization of mitochondrial respiratory enzyme activities, with combined L1 and DFO treatment being the most efficient, followed, in decreasing order, by DFO and L1 as single-drug treatments. Judged by tissue iron concentrations, mitochondrial enzyme activity, and hepatic histology, we could find no evidence of a paradoxical aggravation of iron toxicity by L1 in either of the two series of studies. Although these data appear to be reassuring, the present controversy related to the role of L1 in the development of hepatic cirrhosis should be eventually settled by clinical studies evaluating the effects of long-term iron-chelating treatment.

Animals↗
PubMed2003

Deferoxamine promotes survival and prevents electrocardiographic abnormalities in the gerbil model of iron-overload cardiomyopathy.

We investigated the time course of electrocardiographic (ECG) changes in the Mongolian gerbil model of iron overload and the effects of the iron chelator deferoxamine (DFO) on these changes. Iron overload was produced with weekly subcutaneous injections of low doses (200 mg/kg/wk) or high doses (800 mg/kg/wk) of iron-dextran. DFO was administered subcutaneously at a dose of 200 mg/kg/day to high-dose animals. Our results show that (1) survival of iron-overloaded gerbils is dose-dependent, with median survival times of 68 and 14 weeks for low- and high-dose animals, respectively; (2) both low and high doses produce prolongation of the PR interval and bradycardia in early stages and prolongation of the QT interval, premature ventricular contractions, variable degrees of atrioventricular block, changes in the ST segment, and T-wave inversion at later stages coinciding with the development of heart failure; (3) DFO prevented death during 20 weeks of high-dose iron-dextran; (4) DFO prevented ECG changes, although delayed prolongation of PR intervals and QRS complexes occurred; and (5) despite marked prolongation of survival and prevention of ECG changes, DFO had modest effects on total cardiac iron content. We speculate that DFO chelates a small iron pool located within the cytoplasm of iron-overloaded cardiomyocytes.

Animals↗
PubMed1989

Modulation of deferoxamine toxicity and clearance by covalent attachment to biocompatible polymers.

A class of high molecular weight iron chelators has been prepared by covalently attaching deferoxamine (DFO), by its amino group, to a variety of biocompatible polymers such as dextran and hydroxyethyl-starch. The iron-binding properties of DFO are virtually unchanged after the attachment procedure, but the toxicity and circulatory half-life are profoundly altered. Competitive iron-binding experiments indicate that the conjugates retain a high affinity for ferric iron. In addition, the derivatives inhibit iron-driven lipid peroxidation as effectively as the parent drug. However, the LD50 in mice (based on DFO equivalents) is approximately 4000 mg/kg for dextran-DFO as compared to 250 mg/kg for free DFO. Consistent with the greatly decreased LD50, intravenous administration of the conjugates in dogs at a dose of 100 mg/kg (body weight) does not cause the severe hypotension associated with intravenous administration of DFO. The plasma half-lives of these adducts are increased greater than 10-fold for dextran-DFO and hydroxyethyl-starch-DFO compared to the free drug. Finally, and most importantly, the conjugates are effective in mediating in vivo iron mobilization and excretion. Because recent evidence implicates iron as an important component of tissue injury in many disease states, these high molecular weight iron chelators may have potential for improved therapy, allowing higher sustained plasma concentrations of the active drug.

Animals↗
PubMed1995

The spin trap alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone stimulates peroxidase-mediated oxidation of deferoxamine. Implications for pharmacological use of spin-trapping agents.

The iron chelator deferoxamine (Desferal; DSFL) reacts with peroxidases and H2O2 to form the DSFL radical (DSFL.), which can be detected by EPR spectroscopy. We have found that DSFL. formation resulting from exposure to H2O2 and any of a number of different peroxidases is greatly enhanced in the presence of the nitrone spin trap alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone (4-POBN). This enhancement was seen at 4-POBN concentrations as low as 200 microM. We observed a modest enhancement of DSFL. formation with 2-methyl-2-nitrosopropane. However, no enhancement was seen with 5,5-dimethyl-1-pyrroline 1-oxide (DMPO) or phenyl-tert-butylnitrone. A modest enhancement was also seen with the nitrone compound pyridine N-oxide. 2-Methyl-2-nitrosopropane and pyridine N-oxide were additionally capable of increasing enzymatic peroxidase activity as measured by o-dianisidine and/or tetramethylbenzidine oxidation. Furthermore, at high concentrations of 4-POBN (50 mM) in the absence of DSFL, we detected a peroxidase/H2O2-dependent 12-line EPR spectrum that likely represents a 4-POBN/.4-POBN nitrogen-centered spin adduct. In the presence of both 4-POBN (10 mM) and DMPO (100 mM), an 18-line EPR spectrum was observed consistent with formation of a DMPO/.4-POBN nitrogen-centered spin adduct. Thus, the nitrone spin trap 4-POBN can enhance the peroxidase-mediated formation of DSFL., possibly via the formation of a transient 4-POBN radical species. These data suggest the importance of assessing the potential for nitrone spin traps to both inhibit and enhance biological oxidation prior to their use as potential pharmacological agents.

Deferoxamine↗
PubMed2006

Deferiprone or deferoxamine vs. combination therapy in patients with beta-thalassemia major: a case study in Taiwan.

Deferiprone (L1) has been recommended as an effective oral chelation therapy for patients with beta-thalassemia major (TM). From 1999 to 2004, 114 patients with TM from five treatment centers were enrolled in this program: iron (Fe) was chelated with L1 in 57 patients, deferoxamine (DFO) in 26, and combined L1/DFO therapy in 31. We found that serum ferritin (SF) was significantly lower in nine patients receiving L1 for more than 5 years (p = 0.04), 22 patients receiving L1 for 1-2 years (p < 0.01) and 31 receiving the combined therapy (p = 0.01), yet significantly higher in those receiving DFO only (p < 0.01). One patient showed transient neutropenia; arthropathy in one patient and gastrointestinal upset in two were noted, with no significant change in alanine aminotransferase (ALT) level. Of 17 patients who were submitted to a liver biopsy, 15 showed no significant change in hepatic fibrosis scores after therapy with L1. None of the 88 patients, including 31 who received the combined therapy, have abandoned oral L1 treatment due to adverse effects. Results of this study proved that L1 or combined therapy with L1 and DFO is effective in reducing SP; incidence of adverse events was low in patients with TM.

Adolescent↗
PubMed2006

Effective combination therapy of deferiprone and deferoxamine for the rapid clearance of excess cardiac IRON and the prevention of heart disease in thalassemia. The Protocol of the International Committee on Oral Chelators.

The International Committee on Oral Chelators (ICOC) combination therapy protocol involving the administration of deferiprone (L1) during the day (80-110 mg/kg/day) and deferoxamine (DFO) (40-60 mg/kg at least 3 days/week) during the night for 8-12 hours using a pump, or the whole 24 hours using an elastomeric pump infuser, has been tested in 11 thalassemia patients (seven males, four females) over a period of 9-28 months. The patients had variable serum ferritin levels (0.54-4.6 mg/L) and cardiac iron load ranging from normal to severe siderosis levels (MRI T2*: 4.7-45 ms). There was a substantial overall reduction in serum ferritin levels (0.17-2.16 mg/L) and normalization of cardiac iron (MRI T2* >20 ms) in all patients. In two patients with severe and moderate cardiac iron load range levels, cardiac iron normalization was achieved within 9-10 months. Two patients on L1 monotherapy (80-120 mg/kg/day) maintained normal range MRI T2* cardiac iron levels over the same period. The ICOC combination therapy protocol appears to be the most effective and least cumbersome form of chelation treatment for the rapid clearance of excess iron from the heart.

Administration, Oral↗
PubMed1987

Lack of effect of deferoxamine, dimethyl sulfoxide, and catalase on monocrotaline pyrrole pulmonary injury.

Monocrotaline pyrrole (MCTP) is a reactive metabolite of the pyrrolizidine alkaloid monocrotaline. MCTP given intravenously to rats causes pulmonary hypertension and right ventricular hypertrophy. Lesions in lungs after MCTP treatment contain macrophages and neutrophils, which may contribute to the damage by generation of reactive oxygen metabolites. Rats were treated with MCTP and agents known to protect against oxygen radical-mediated damage in acute models of neutrophil-dependent lung injury. Rats received MCTP and deferoxamine mesylate (DF), dimethyl sulfoxide (DMSO), or polyethylene glycol-coupled catalase (PEG-CAT). MCTP/vehicle-treated controls developed lung injury manifested as increased lung weight, release of lactate dehydrogenase into the airway, and sequestration of 125I-labeled bovine serum albumin in the lungs. Cotreatment of rats with DF, DMSO, or PEG-CAT did not protect against the injury due to MCTP. These results suggest that toxic oxygen metabolites do not play an important role in the pathogenesis of MCTP-induced pulmonary injury.

Animals↗
PubMed2003

Potential myocardial iron content evaluation by magnetic resonance imaging in thalassemia major patients treated with Deferoxamine or Deferiprone during a randomized multicenter prospective clinical study.

The purpose of this study was to evaluate if the variations of heart magnetic resonance imaging in beta-thalassemia major patients treated with Deferoxamine B mesylate (DF) or Deferiprone (L1) chelation therapy is a useful tool of the indirect myocardial iron content determination. For this reason, a prospective study was carried out. Seventy-two consecutive patients with beta-thalassemia major (35 treated with DF and 37 with L1) were studied. The main outcome results were laboratory parameters including determination of the liver iron concentration (LIC) and magnetic resonance imaging (MRI) of the heart and liver. The heart to muscle signal intensity ratios (HSIRs) were significantly increased in both the DF (t = -2.8; p < 0.01) and L1 (t = -3.1; p < 0.01) groups after one year of treatment No statistically significant difference in the values of HSIRs was present between the two groups at the beginning of treatment (p = 0.25; t = 1.13), and after one year of treatment (p = 0.20; t = 1.28). The HSIR were inversely correlated to the LIC (r = -0.52; p < 0.001) but not with ferritin levels (r = 0.10; p = 0.18). A positive correlation was found between the variation of HSIRs and that of the liver signal intensity ratios (r=0.52; p < 0.001), and a mild correlation (r = 0.40; p < 0.001) was found between the gamma glutamyltransferase (gammaGt) levels and the HSIRs values. Our data confirm that heart MRI is sensitive enough to detect significant variations of the mean HSIR during iron chelation with DF or L1.

Administration, Oral↗