Ferric Carboxymaltose

Ferric carboxymaltose is an intravenous iron-carbohydrate complex that permits large single doses, up to 1000 mg of elemental iron. It is supplied as 50 mg/mL elemental iron.

Classification. Parenteral iron; iron-carbohydrate complex.

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

Pharmacokinetics. Terminal half-life is about 7 to 12 hours. Renal clearance is negligible, and iron remains in the body for repeated use.

Iron deficiency anaemia (adults, oral iron failed, not tolerated or not suitable).

• Dose: based on weight and haemoglobin. For haemoglobin under 10 g/dL the usual cumulative dose is 1500 mg for 35 to under 70 kg and 2000 mg for 70 kg and over; for haemoglobin of 10 g/dL or more it is 1000 mg and 1500 mg respectively. Alternatively use the deficit calculation (weight in kg multiplied by target minus actual haemoglobin in g/dL, multiplied by 2.4, plus 500 mg).
• Maximum: 1000 mg (or 15 mg/kg) in a single dose, no more than once weekly; cumulative dose for each course 2000 mg. Loading dose: none.
• Another widely used scheme is 750 mg given twice, at least 7 days apart, for adults 50 kg and over.

Iron deficiency in heart failure.

• Dose by weight and haemoglobin: 500 to 1000 mg in the correction phase, repeated every 12 weeks if ferritin is under 100 µg/L, or 100 to 300 µg/L with transferrin saturation under 20%, as maintenance.

Children. Licensed in some regions from 1 year of age at 15 mg/kg (maximum 750 mg) each dose, two doses at least 7 days apart; in other regions not advised under 14 years.

Adjustments. Kidney: none needed; non-dialysis chronic kidney disease is licensed. Liver: avoid in decompensation. Hypophosphataemia risk: check phosphate before repeat dosing in those at risk.

Contraindications. Hypersensitivity, iron overload, anaemia not due to iron deficiency, and serious active infection.

Adverse effects. Common: headache, nausea, flushing, transient hypertension and staining at extravasation. Serious: hypophosphataemia (often asymptomatic and transient but occasionally prolonged, with osteomalacia and fractures after repeated doses), and hypersensitivity reactions.

Interactions. Do not give with oral iron. Other agents that lower phosphate (for example some antacids and diuretic regimens) add to the risk.

Pregnancy and breastfeeding. Avoid in the first trimester; use in the second and third trimesters when benefit outweighs risk. Compatible with breastfeeding.

Common errors. Repeat dosing without checking phosphate in patients with prior hypophosphataemia, malabsorption or vitamin D deficiency; exceeding 1000 mg in a week.

Preparation. Dilute in 0.9% sodium chloride only; 1000 mg in up to 250 mL over at least 15 minutes. A slow intravenous push of smaller doses is possible; do not give faster than the labelled rate.

Baseline. Haemoglobin, ferritin, transferrin saturation, phosphate.

Monitoring. Observe for 30 minutes after each dose. Haemoglobin at 4 weeks; ferritin and transferrin saturation at least 4 weeks after the last dose. Check phosphate at 2 to 4 weeks after repeated dosing when symptoms such as bone pain or weakness develop.

Referral and escalation. Persistent hypophosphataemia (under 0.6 mmol/L) needs phosphate replacement and a change to another iron product. Anaphylaxis: adrenaline 0.5 mg intramuscularly (adults).