High-dose vitamin C (more than 500 mg daily) during deferoxamine therapy has been associated with cardiac dysfunction in patients with severe chronic iron overload.
Vitamin C increases the availability of mobilised iron and free iron formation, favouring oxidative injury to the already overloaded myocardium; cardiac dysfunction is described in the deferoxamine label with combined high-dose therapy.
Echocardiogram with ventricular function assessment, ferritin, liver function, fluid balance and heart failure symptoms.
Dyspnoea, oedema, orthopnoea, tachycardia, rapid weight gain.
If vitamin C deficiency is documented, do not exceed 500 mg daily (50 mg daily in children) and start only after stabilisation on deferoxamine; stop immediately if signs of heart failure appear.
FDA — Desferal (deferoxamine mesylate) for injection, Drug Interactions (vitamin C: cardiac dysfunction in severe iron overload with doses > 500 mg daily): https://www.accessdata.fda.gov/drugsatfda_docs/label/2007/016267s044lbl.pdf; Novartis — DESFERAL prescribing information; INFARMED Prontuário Terapêutico (11th ed., 2012), DEFEROXAMINE entry (p. 520).
Multivitamin supplements containing iron defeat chelation (deferoxamine binds ingested iron instead of stored iron); high-dose vitamin C alters the distribution of chelated iron.
Do not take multivitamins containing iron; vitamin C only if indicated at doses controlled by the thalassaemia team.
Prontuário, DESFERAL monograph (doses adjusted to ferritin; slow IV administration); EMC-UK desferrioxamine SmPC 4.4/4.5.
The iron-deferoxamine complex is renally excreted — in renal impairment elimination is reduced and released iron redistributes.
Adjust dose according to ferritin and renal function; consider slow IV route during haemodialysis (chronic iron/aluminium protocol).
Prontuário Terapêutico INFARMED, DESFERAL monograph (doses adjusted to ferritin; haemodialysis infusion).
The safety of deferoxamine in pregnancy is not established; animal data show skeletal/embryotoxicity at high doses. However, untreated iron overload (transfusion-dependent thalassaemia) is also harmful to pregnancy — benefit may justify use in severe overload.
Avoid unless the benefit (reducing iron overload) clearly justifies the risk; limit chelation to the period strictly necessary and document the decision.
Excretion into milk is unknown; breastfeeding is advised against during treatment due to lack of data.
Prontuário Terapêutico INFARMED — 8.3 (Deferoxamine); EMC-UK (MHRA) — Desferrioxamine SmPC: https://www.medicines.org.uk/emc/product/1644/smpc (section 4.6: "avoid unless clearly necessary").
Clinical and educational support tool. The information does not replace a medical prescription or the opinion of a qualified healthcare professional.
Chelates free Fe3+ and ferritin/haemosiderin iron; renal and biliary excretion of ferrioxamine (wine-coloured urine).
Bacterial siderophore: high-affinity octahedral binding to Fe3+ (log K ~ 31), forming soluble excretable ferrioxamine. Does not remove iron from haemoglobin or cytochromes.
Oral: < 15% (prefer SC/IM/IV); continuous SC optimises hepatic iron chelation.
Hepatic metabolism by plasma amine oxidases; renal excretion of ferrioxamine and biliary of bound iron.
~ 20–30 min (SC/IM); ~ 5–10 min (IV).
Medicines from the same therapeutic group (ATC classification) or the same pharmacological class.
