Iron Dextran

Iron dextran is an intravenous or deep intramuscular iron-dextran complex, supplied as 50 mg/mL elemental iron. It carries a risk of anaphylaxis higher than other parenteral irons and is used mainly where other intravenous iron is unavailable.

Classification. Parenteral iron; iron-dextran complex.

Mechanism. Iron is cleared by the reticuloendothelial system and released to transferrin for erythropoiesis and storage.

Pharmacokinetics. Plasma half-life is about 5 to 20 hours for intravenous use, and slow and variable for the intramuscular route, with absorption over weeks.

Iron deficiency (adults) when oral iron is not tolerated or ineffective.

• Test dose: 25 mg (0.5 mL) intravenously slowly over at least 30 seconds, followed by observation for at least 1 hour before the remaining dose.
• Intravenous injection or infusion: 100 mg (2 mL) daily until the calculated total iron deficit is reached. Maximum daily dose 100 mg for injection (2 mL).
• Total dose infusion: some centres give the full deficit, up to 20 mg/kg, as a single infusion in 500 mL of 0.9% sodium chloride over 4 to 6 hours after a test dose.
• Intramuscular: 100 mg (2 mL) daily by deep injection into the upper outer buttock with a Z-track technique, alternating sides; avoid unless intravenous access is impossible.
• Total deficit: weight in kg multiplied by (target minus actual haemoglobin in g/dL), multiplied by 2.4, plus 500 mg.

Children. Under 4 months not advised. Daily maximum: 25 mg for under 5 kg, 50 mg for 5 to 10 kg, 100 mg for over 10 kg.

Adjustments. Kidney: no reduction. Liver: avoid in decompensation. Weight: dose by deficit.

Contraindications. Prior reaction to iron dextran, anaemia not caused by iron deficiency, iron overload, decompensated liver disease, acute pyelonephritis.

Boxed-warning-level risk. Anaphylactic reactions, including fatal, can follow the test dose or therapeutic dose. Give only where staff and resuscitation equipment are present.

Adverse effects. Pain and skin staining at intramuscular sites, arthralgia and myalgia, delayed fever, headache, lymphadenopathy, hypotension, flushing.

Interactions. Not given with oral iron. Increased reaction risk in patients on angiotensin-converting-enzyme inhibitors. Interferes with some laboratory tests for several days.

Pregnancy and breastfeeding. Avoid in the first trimester; use in later trimesters only if no safer intravenous iron is available.

Common errors. Omitting the test dose; giving a rapid bolus; intramuscular staining from poor technique.

Preparation. Dilute in 0.9% sodium chloride only (not dextrose); infusion at a rate of up to 50 mg/min for slow infusion.

Baseline. Haemoglobin, ferritin, transferrin saturation.

Monitoring. Observe for at least 1 hour after the test dose and 30 minutes after each further dose. Haemoglobin at 4 weeks; ferritin at least 4 weeks after the last dose.

Referral and escalation. For anaphylaxis: stop the infusion, give adrenaline 0.5 mg intramuscularly (adults), repeat after 5 minutes if required, with airway support and fluids.