Deferoxamine chronic overload

Chronic iron overload in the absence of anemia is most efficiently treated by intermittent phlebotomy. One unit of blood can be removed every week or so until all of the excess iron is removed. Iron chelation therapy using parenteral deferoxamine is much less efficient as well as more complicated, expensive, and hazardous, but it may be the only option for iron overload that cannot be managed by phlebotomy, such as the iron overload experienced by patients with thalassemia major. 

Deferoxamine (see also Chapters 58 and 59) Chelates excess iron Reduces the toxicity associated with acute or chronic iron overload Treatment of acute iron poisoning and for inherited or acquired hemochromatosis that is not adequately treated by phlebotomy Preferred route of administration is IM or SC Toxicity Rapid IV administration may cause hypotension acute respiratory distress has been observed with long infusions neurotoxicity and increased susceptibility to certain infections has occurred with longterm use... 

When used in patients without iron overload, deferoxamine can cause iron deficiency (12). In 20 patients, there were falls in ferritin concentrations in six, requiring withdrawal of deferoxamine and parenteral administration of iron dextran (12). Monitoring ferritin concentrations is therefore recommended in patients receiving deferoxamine for aluminium overload. On the other hand, the administration of deferoxamine (500mg/day by subcutaneous infusion) improves chronic anemia in patients with rheumatoid arthritis (77). This effect is thought to be achieved through increased erythropoietin responsiveness, secondary to iron chelation. Iron chelation with deferoxamine also improves hemopoiesis in patients with myelodysplastic syndromes and can reduce transfusion dependency (78). Exactly how deferoxamine works in these patients remains to be explained. 

Patients with inherited or acquired anemias that require regular blood transfusions frequently have symptoms or laboratory evidence of iron overload. Deferoxamine given subcutaneously at 40 mg kg over 8-12 h has been the standard of therapy for these patients. Patients receiving higher doses (e.g., 125 mg kg demonstrated ocular toxicity of blurriness, loss of night vision, and optic neuropathy. Auditory toxicity has been noted as well. Up to 25% of patients on chronic deferoxamine have some impairment of high-frequency hearing. 

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