Iron Isomaltoside (Ferric Derisomaltose)
Usage
Iron isomaltoside is prescribed for the treatment of iron deficiency anemia (IDA) in adults when oral iron therapy is ineffective, poorly tolerated, or when there’s a clinical need for rapid replenishment of iron stores. This includes patients with chronic kidney disease (CKD) and those with other chronic diseases like inflammatory bowel disease (IBD), malignancies, and rheumatoid arthritis. It is classified as a hematinic agent. Its mechanism of action involves providing a source of iron that is readily incorporated into hemoglobin, thereby increasing red blood cell production and improving oxygen-carrying capacity.
Alternate Names
Iron isomaltoside is also known as ferric derisomaltose. A common brand name is Monofer®.
How It Works
Pharmacodynamics: Iron isomaltoside is a complex of ferric hydroxide and isomaltoside, a carbohydrate. The iron is tightly bound within a matrix-like structure, allowing for controlled release of iron to iron-binding proteins like transferrin. Transferrin delivers the iron primarily to the bone marrow for incorporation into hemoglobin, the protein responsible for oxygen transport in red blood cells. The increased hemoglobin levels lead to a rise in red blood cell count and improved oxygen delivery to tissues.
Pharmacokinetics: Following intravenous administration, the iron in iron isomaltoside is rapidly taken up by the reticuloendothelial system, primarily in the liver and spleen. The iron is then gradually released from the isomaltoside complex and becomes available for erythropoiesis (red blood cell formation). The pharmacokinetics of iron isomaltoside is non-linear, particularly at lower doses. Iron Isomaltoside is eliminated primarily through incorporation into hemoglobin. Any excess unbound iron is excreted by the kidneys.
Dosage
Standard Dosage
Adults:
The dosage is individualized based on the total iron deficit calculated using the Ganzoni formula or a simplified dosing table.
- Ganzoni formula: Total iron need (mg) = body weight (kg) x (target Hb - actual Hb)(g/dL) x 2.4 + iron stores (mg). Target Hb is generally 15 g/dL, but lower targets might be considered in specific cases. Iron stores can be estimated as 500 mg in small women and 1000 mg in men. Some guidelines suggest using 10-15 mg iron/kg body weight for iron stores calculation.
- Simplified dosing table: This provides pre-calculated doses based on Hb levels and body weight.
Administration: Iron isomaltoside is administered intravenously, either as a slow intravenous injection (bolus) or as an intravenous infusion. For bolus injection, doses up to 500 mg can be given at a maximum rate of 250 mg iron/minute, undiluted or diluted in 0.9% sodium chloride. For infusion, doses up to 20 mg iron/kg (maximum single dose of 1500 mg) can be administered over 20 minutes or longer for doses up to 1000 mg and longer than 30 minutes for doses greater than 1000 mg. Total doses greater than 20 mg iron/kg must be divided into two administrations spaced at least one week apart. Single doses greater than 1500 mg are not recommended.
Children: Iron isomaltoside is not recommended for use in children under 18 years due to insufficient data on safety and efficacy.
Special Cases:
- Elderly Patients: No specific dose adjustment is needed, but careful risk-benefit assessment is required due to potentially increased risk of adverse events. Close monitoring is essential.
- Patients with Renal Impairment: Dosage adjustments are generally not necessary, except for those on hemodialysis where iron isomaltoside can be administered during dialysis sessions. Dosage calculations should still be performed based on the Ganzoni formula.
- Patients with Hepatic Dysfunction: Caution is advised in patients with decompensated liver disease.
- Patients with Comorbid Conditions: Use with caution in patients with cardiovascular disease and monitor for hypotension.
Clinical Use Cases Information regarding specific use cases is limited to emergency and surgical use as indicated by the provided texts.
Dosage Adjustments Dose adjustments should be based on patient tolerance, response to therapy, and laboratory parameters such as Hb and ferritin levels.
Side Effects
Common Side Effects
Nausea, rash, injection site reactions (pain, swelling, discoloration), headache, dizziness, fatigue, back pain.
Rare but Serious Side Effects
Hypersensitivity reactions (including anaphylaxis and anaphylactoid reactions), hypotension, dyspnea, bronchospasm, angioedema.
Long-Term Effects Iron overload with chronic use.
Adverse Drug Reactions (ADR)
Serious hypersensitivity reactions including anaphylactic shock.
Contraindications
Known hypersensitivity to iron isomaltoside or other parenteral iron products, history of multiple allergies, non-iron deficiency anemia, iron overload (e.g., hemochromatosis), active hepatitis or decompensated liver cirrhosis.
Drug Interactions
Oral iron absorption is reduced when given concomitantly with iron isomaltoside. Oral iron should not be started within 5 days of the last iron isomaltoside administration. Potential interactions with other medications, including bisphosphonates and antibiotics like quinolones, may occur.
Pregnancy and Breastfeeding
Iron isomaltoside should generally be avoided during pregnancy unless the benefits outweigh the potential risks. Limited data suggest that breast milk iron levels increase transiently after administration, returning to normal within a week. No harmful effects on infants have been observed; however, clinical data are limited.
Drug Profile Summary
- Mechanism of Action: Provides iron for incorporation into hemoglobin, increasing red blood cell production.
- Side Effects: Nausea, rash, injection site reactions, hypersensitivity.
- Contraindications: Hypersensitivity, iron overload, non-iron deficiency anemia.
- Drug Interactions: Oral iron, some antibiotics, bisphosphonates.
- Pregnancy & Breastfeeding: Use with caution.
- Dosage: Individualized based on total iron deficit. IV bolus or infusion.
- Monitoring Parameters: Hb, ferritin, transferrin saturation, blood pressure during administration.
Popular Combinations
Often used in conjunction with erythropoiesis-stimulating agents (ESAs) in patients with CKD.
Precautions
Monitor for hypersensitivity reactions during and after administration. Pre-existing conditions like cardiovascular disease, liver dysfunction, and immune disorders warrant careful monitoring.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Iron Isomaltoside?
A: The dosage is individualized based on the patient’s total iron deficit, calculated using the Ganzoni formula or a simplified table. It is administered IV as a bolus or infusion, with the maximum single dose not exceeding 1500 mg.
Q2: Can Iron Isomaltoside be used in children?
A: No, it’s not recommended for children under 18 due to insufficient data on safety and efficacy.
Q3: What are the most common side effects?
A: Nausea, rash, and injection site reactions are common side effects.
Q4: Are there any serious side effects to be aware of?
A: Yes, hypersensitivity reactions, including anaphylaxis, can occur. Patients should be monitored closely during and after administration.
Q5: Can Iron Isomaltoside be used during pregnancy?
A: It should generally be avoided during pregnancy unless the benefits clearly outweigh the potential risks to the fetus.
Q6: How does Iron Isomaltoside interact with oral iron supplements?
A: Concurrent administration of oral iron reduces the absorption of both medications. Oral iron therapy should be initiated at least 5 days after the last iron isomaltoside dose.
Q7: What monitoring parameters are essential during iron isomaltoside administration?
A: Blood pressure and pulse should be monitored during and after administration to detect hypersensitivity reactions. Hemoglobin and ferritin levels are also monitored to assess response to therapy.
Q8: What precautions are needed for patients with liver disease?
A: Patients with decompensated liver cirrhosis should not receive iron isomaltoside. Patients with less severe liver disease require careful monitoring.
Q9: Can iron isomaltoside be used in patients with chronic kidney disease?
A: Yes, it can be used in patients with chronic kidney disease, including those on dialysis.
A: Total iron deficit (mg) = body weight (kg) * (target Hb - actual Hb)(g/dL) * 2.4 + iron stores (mg).
