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Researchers have compared the risk of anaphylaxis with different intravenous (IV) iron products and found evidence to suggest that iron dextran poses the greatest risk.
Compared with nondextran formulations, iron dextran was associated with a higher cumulative risk of anaphylaxis and an increased risk of anaphylaxis at first administration.
Iron sucrose was associated with the lowest risk of anaphylaxis, both cumulative and at first administration.
Cunlin Wang, MD, PhD, of the US Food and Drug Administration in Silver Spring, Maryland, and his colleagues conducted this research and reported the results in JAMA.
The researchers studied 688,183 recipients of IV iron enrolled in the fee-for-service Medicare program from January 2003 to December 2013.
The team examined administrations of IV iron dextran, gluconate, sucrose, or ferumoxytol. They identified 247,500 iron dextran and 440,683 nondextran users during the study period.
Overall, there were 274 cases of anaphylaxis at first exposure to IV iron and an additional 170 cases during subsequent iron administrations.
At first administration, iron dextran was associated with a higher anaphylaxis risk than nondextran formulations. The risk of anaphylaxis was 68 per 100,000 persons for iron dextran and 24 per 100,000 persons for all nondextran products combined. The odds ratio—adjusted for age, indication, history of coronary heart disease, and hypertension—was 2.6 (P<0.001).
Among the nondextran products, the risk of anaphylaxis at first administration was higher with both iron gluconate and ferumoxytol than with iron sucrose. When compared with iron sucrose, the adjusted odds ratio of anaphylaxis was 3.6 for iron dextran, 2.0 for iron gluconate, and 2.2 for ferumoxytol.
Because each IV iron product has a specific recommended dose and schedule of administration, the researchers also calculated the cumulative risk of anaphylaxis based on both the number of administrations and the clinically relevant repletion level of iron (1000 mg) achieved within 12 weeks.
The cumulative risk of anaphylaxis over multiple administrations was highest for iron dextran, followed by ferumoxytol, iron gluconate, and iron sucrose.
The estimated cumulative anaphylaxis risk following total iron repletion of 1000 mg administered within a 12-week period was highest with iron dextran (82 per 100,000 persons) and lowest with iron sucrose (21 per 100,000 persons).
The researchers noted that the mechanism of anaphylactic reaction after IV iron remains unknown.
