About This Topic

This information provides clinical context for the Deferoxamine Dose Calculator (Iron Toxicity) calculator. Deferoxamine is a chelating agent used to treat acute iron poisoning by binding to ferric iron, forming ferrioxamine, a water-soluble complex that is then excreted by the kidneys. Its use is reserved for patients with evidence of systemic toxicity, not just an elevated serum iron level.

Outputs Explained

The calculator provides two key outputs to guide intravenous (IV) administration:

• Patient Infusion Rate (mg/hr): This is the total dose of deferoxamine the patient should receive per hour, calculated based on a standard rate of 15 mg/kg/hr.
• Infusion Pump Rate (mL/hr): This optional output is calculated if you provide the final concentration of the mixed IV solution (in mg/mL). It tells you the volumetric rate at which to set the infusion pump to deliver the correct dose.

How to Use the Calculator

To determine the correct infusion parameters, provide the following clinical data:

1. Patient Weight: Enter the patient's actual body weight. You can input this value in either kilograms (kg) or pounds (lbs).
2. Indication(s): Select at least one clinical criterion for initiating deferoxamine therapy. Chelation is indicated for significant toxicity, such as severe symptoms (shock, coma), metabolic acidosis, or a very high peak serum iron level (>500 mcg/dL).
3. Infusion Preparation (Optional): If you know the final concentration of the deferoxamine solution prepared by pharmacy (e.g., 500 mg in 50 mL NS = 10 mg/mL), enter it here to calculate the precise pump rate in mL/hr.

Dosing Overview

For acute iron toxicity, the standard intravenous dosing of deferoxamine is a continuous infusion.

• Standard Infusion Rate: 15 mg/kg/hour.
• Maximum Daily Dose: The total dose should generally not exceed 6 grams in a 24-hour period.
• Duration: Therapy is continued until the patient is clinically improved, metabolic acidosis resolves, and the "vin-rosé" (reddish-brown) urine color returns to normal. This typically takes 12-24 hours.

Doses higher than 15 mg/kg/hr are associated with an increased risk of hypotension and ARDS and should only be used in severe cases under the guidance of a toxicologist or Poison Control Center.

Switching Therapy

In the setting of acute iron toxicity, deferoxamine is the primary and standard-of-care intravenous chelator. Switching to other chelators during the acute phase is not standard practice. Oral iron chelators are not used for acute poisoning.

Interrupting or Modifying Infusion

Deferoxamine is administered as a continuous infusion. There is no concept of a "missed dose." However, the infusion rate may need to be adjusted or temporarily paused based on the patient's clinical response, particularly hemodynamics.

• Hypotension: If the patient develops hypotension, the first step is to slow the infusion rate. If hypotension persists, the infusion may need to be paused while fluid resuscitation is administered.
• ARDS: If signs of acute respiratory distress syndrome develop, the infusion should be stopped immediately and expert consultation sought.

Safety Alerts

Deferoxamine therapy carries significant risks that require careful patient monitoring.

• Hypotension: This is the most common adverse effect, often related to a rapid infusion rate. Continuous blood pressure monitoring is essential, especially during the initial phase of treatment.
• Acute Respiratory Distress Syndrome (ARDS): A serious complication associated with high-dose (>15 mg/kg/hr) or prolonged (>24 hours) infusions. Monitor respiratory status closely.
• Infection Risk: Deferoxamine is a siderophore that can promote the growth of certain organisms, particularly Yersinia enterocolitica. Patients may be at increased risk for sepsis.
• Ocular and Auditory Toxicity: These are rare with short-term use for acute poisoning but are known risks with chronic therapy.

Frequently Asked Questions (FAQ)

Why is a 'vin-rosé' urine color significant?
The iron-deferoxamine complex, ferrioxamine, has a distinct reddish-brown color. Its presence in the urine confirms that the drug is successfully binding to iron and being eliminated. The return of normal urine color is one endpoint for therapy.

What should I do if the patient becomes hypotensive?
Slow the infusion rate immediately. If necessary, provide IV fluid boluses. The calculator bases its dose on 15 mg/kg/hr, which helps minimize this risk, but it can still occur.

When should the deferoxamine infusion be stopped?
Therapy is generally stopped when all three criteria are met: (1) the patient is clinically well (e.g., resolution of shock, acidosis, and altered mental status), (2) metabolic acidosis has resolved, and (3) the urine is no longer "vin-rosé" colored.

Can I give deferoxamine intramuscularly (IM) for acute toxicity?
The IM route is not recommended for patients with shock or systemic toxicity, as absorption can be erratic. IV infusion is the standard of care for all significant poisonings.

Does hemodialysis remove the iron-deferoxamine complex?
Yes, ferrioxamine can be removed by hemodialysis. This may be considered in patients with severe iron toxicity complicated by renal failure.

Why is a peak iron level not the only indication for therapy?
Clinical signs of toxicity are more important than the absolute iron level. A patient may have a high level but be asymptomatic, while another may have a lower level with severe acidosis. Treatment decisions should be based on the overall clinical picture.

What is the maximum recommended daily dose of deferoxamine?
The total daily dose should generally not exceed 6 grams, although higher doses have been used in extreme cases under expert guidance due to the increased risk of ARDS.

How does deferoxamine increase the risk of *Yersinia* sepsis?
Yersinia enterocolitica is an iron-loving bacterium. Deferoxamine acts as a siderophore, which the bacteria can use to acquire iron, promoting its rapid growth and potentially leading to overwhelming sepsis.

References

• 1. Novartis. DESFERAL (deferoxamine mesylate) for injection Prescribing Information. U.S. Food and Drug Administration. Revised 2018. https://www.accessdata.fda.gov/drugsatfda_docs/label/2018/016267s044lbl.pdf
• 2. Yuen HW, Becker W. Iron Toxicity. [Updated 2023 Jun 20]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. https://www.ncbi.nlm.nih.gov/books/NBK459224/
• 3. Howland MA. Antidotes in depth (AIDs): Deferoxamine. In: Goldfrank's Toxicologic Emergencies, 11th ed, Hoffman RS, Howland MA, Lewin NA, et al (Eds), McGraw-Hill, New York 2019.
• 4. American Association of Poison Control Centers. Find Your Local Poison Center. https://www.aapcc.org/find-your-poison-center