Injectafer: 7 things you should know

Medically reviewed by Carmen Pope, BPharm. Last updated on July 3, 2023.

1. How it works

• Injectafer is a brand (trade) name for ferric carboxymaltose injection, which may be used for the treatment of iron deficiency anemia (IDA).
• Injectafer consists of a shell made of a carbohydrate polymer called carboxymaltose that is tightly bound around an iron core. Its structure is similar to naturally occurring ferritin, which is the body's iron storage protein. Once Injectafer is injected into the body, it is likely taken up by macrophages of the RES which break down the carbohydrate shell and slowly release iron. The iron may be then stored in the liver as ferritin or transported to cells in the liver, spleen, or bone marrow where it can be used for hemoglobin synthesis and red blood cell formation.
• Iron is a vital mineral for our survival. Iron is needed to make hemoglobin for red blood cells, which carries oxygen around the body. When iron levels are low, the body makes less hemoglobin and therefore a reduced number of red blood cells are made, causing IDA.

2. Upsides

• May be used to treat iron deficiency anemia (IDA) in adult patients who are intolerant to oral iron or have had an unsatisfactory response to oral iron, with non-dialysis dependent chronic kidney disease, or to improve exercise capacity in people with New York Heart Association (NYHA) class II/III heart failure.
• May also be used to treat iron deficiency anemia in children aged 1 year of age and older who are intolerant to oral iron or have an unsatisfactory response to oral iron.
• Dextran-free (dextran has been associated with allergic reactions and other side effects).
• Gradually releases iron within the body which may decrease the potential for side effects.
• The gradual release of iron also means the protein used to transport iron, called transferrin, does not become fully saturated with iron, and a greater proportion of the iron contained in Injectafer is used by the body.
• 100% of the iron is delivered into the bloodstream (on average, only 10% of oral iron is absorbed).
• For patients weighing 50kg or more, usually only 2 administrations are needed (each administration can be up to 750mg at least 7 days apart). Alternatively, a single dose may be given at 15 mg/kg body weight up to a maximum of 1000mg IV. For people weighing less than 50kg, 15 mg/kg Injectafer should be given in two doses separated by at least 7 days.
• Injectafer can be given by slow intravenous (IV) push that takes roughly 8 minutes, or as an IV infusion that takes at least 15 minutes. Times may be longer due to preparation and administration. Monitoring for 30 minutes following the infusion is necessary in case an allergic reaction happens.
• Given as either a single injection or as two injections separated by at least 7 days. Treatment may need to be repeated if iron deficiency anemia reoccurs.
• Available in two strengths: 750mg iron/15mL or 1000mg iron/20mL.
• The formulation of Injectafer means the iron it contains is released slowly, in a controlled fashion.
• Injectafer increases iron in the body to close to an ideal level. It then takes 2 to 3 weeks for the bone marrow to use the iron to make hemoglobin for the red blood cells and then symptoms of anemia will be corrected.
• A good option to consider when oral iron fails.

3. Downsides

If you are between the ages of 18 and 60, take no other medication or have no other medical conditions, side effects you are more likely to experience include:

• Nausea, high blood pressure, flushing, dizziness, low levels of phosphorous in the blood, and injection site reactions are the most common side effects reported.
• Monitor phosphate levels in patients at high risk for low phosphate levels, such as those with a history of gastrointestinal disorders associated with malabsorption of fat-soluble vitamins or phosphate, concurrent or prior use of medications that affect proximal renal tubular function, hyperparathyroidism, vitamin D deficiency, or malnutrition. In most cases, hypophosphatemia resolved within three months.
• High blood pressure was reported in 4% of people in clinical trials; transient elevations with symptoms such as facial flushing, dizziness, and nausea were observed in 6%. Usually occurs immediately after the injection and resolves within 30 minutes. Monitor patients.
• The safety of Injectafer has not been established in children.
• An overdosage of Injectafer may lead to hemosiderosis; symptoms include multiple joint disorders, walking disability, and asthenia (weakness or lack of energy).
• Iron injections have been associated with allergic reactions. Symptoms may include a rash, itching, dizziness, lightheadedness, swelling, and breathing problems. Monitor for 30 minutes after the injection. Serious anaphylactic reactions have been reported in 0.1% of patients receiving Injectafer. Not suitable for people with a previous reaction to iron preparations.
• This may cause overestimations in laboratory values of serum iron and transferrin-bound iron in the 24 hours following administration of Injectafer because it also measures the iron contained in Injectafer.
• Weigh up risks versus benefits before administering to pregnant women. Iron injections have been associated with hypersensitivity reactions which may cause fetal bradycardia and other serious consequences, especially during the second and third trimesters. Animal studies have reported fetal malformations and increased implantation loss when ferric carboxymaltose was administered to pregnant rabbits. Published human data do not indicate an association between IV ferric carboxymaltose and major birth defects and miscarriage. Untreated IDA is also a risk to the mother and fetus. Iron is present in breast milk and reported adverse reactions among breastfed infants include constipation and diarrhea.

Note: In general, seniors or children, people with certain medical conditions (such as liver or kidney problems, heart disease, diabetes, seizures) or people who take other medications are more at risk of developing a wider range of side effects. View complete list of side effects

4. Bottom Line

Injectafer is an iron injection that may be used in adults and children aged 1 year and older to treat iron deficiency anemia (IDA). It is dextran-free, which lowers the risk of allergic reactions and other side effects, although after an Injectafer injection in a healthcare provider's facility, a person still requires monitoring for 30 minutes. Injectafer works quickly and symptom improvement in IDA may be noticed within a week although it may take 2 to 3 weeks for laboratory values to normalize.

5. Tips

• Injectafer injections are given by a healthcare provider. Although the injections take about 8 minutes if given by a slow IV push or 15 minutes if given by infusion, expect to be at the clinic for 45minutes to an hour which allows for preparation time beforehand and monitoring time afterward.
• You may eat and drink normally before and after your appointment.
• Your dose of Injectafer may be given as two doses separated by at least seven days or, if the dose prescribed is less than 1000mg, as a single dose treatment.
• Tell your doctor if you have had a previous reaction to IV iron, have high blood pressure, are breastfeeding, or if you are pregnant or planning to become pregnant.
• Be sure to report any signs and symptoms of an allergic reaction that may develop during and after your Injectafer injection, such as a rash, itching, dizziness, lightheadedness, swelling, and breathing problems. Injectafer can also cause high blood pressure and symptoms may include facial flushing, dizziness, or nausea.

6. Response and effectiveness

• Works rapidly and effectively to correct iron levels and symptom improvement may be noticed within a week. It takes 2 to 3 weeks for the bone marrow to use the iron to make hemoglobin for red blood cells which will improve IDA and anemia symptoms such as reduced concentration, energy levels, breathlessness, and fatigue.
• Trials have reported a greater absolute increase in hemoglobin from baseline with Injectafer when compared to oral iron (mean change from baseline 1.6 with Injectafer compared to 0.8 with oral iron).
• 57% of patients receiving Injectafer reached hemoglobin levels of >12g/dL compared with only 29% who received oral iron at day 35.
• Secondary endpoints included improvements in ferritin and TSAT. People taking oral iron supplements had diminished iron stores at day 35, suggesting iron losses outpaced iron supplementation (baseline ferritin reduced by 3.83 and baseline TSAT reduced by 5.7%). In contrast, after Injectafer, baseline ferritin increased by 264.21, and baseline TSAT increased by 12.99%).
• Injectafer has a neutral pH and a neutral plasma osmolarity.

7. Interactions

Medicines that interact with Injectafer may either decrease its effect, affect how long it works for, increase side effects, or have less of an effect when taken with Injectafer. An interaction between two medications does not always mean that you must stop taking one of the medications; however, sometimes it does. Speak to your doctor about how drug interactions should be managed.

Common medications that may interact with Injectafer include:

• ACE inhibitors such as captopril, enalapril, or quinapril
• dimercaprol
• erdafitinib
• other iron preparations, such as carbonyl iron, ferrous gluconate, or ferrous sulfate
• multivitamin preparations
• vitamin e.

Note that this list is not all-inclusive and includes only common medications that may interact with Injectafer. You should refer to the prescribing information for Injectafer for a complete list of interactions.

References

• Injectafer (ferric carboxymaltose). Updated 02/2023. American Regent, Inc. https://www.drugs.com/pro/injectafer.html

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use Injectafer only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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