In older patients the risk of anaphylaxis is highest with iron dextran and lowest with iron sucrose, a large FDA sponsored study confirms.

More than twice as many older recipients of iron dextran experienced anaphylaxis as those receiving other formulations, with an odds ratio of 2.6 (95% confidence interval [CI], 2.0 – 3.3; P<.001), after adjusting for age, indication, history of coronary heart disease, and hypertension, researchers reported in JAMA.

Because each IV iron product has a specific recommended dose and schedule of administration, the cumulative risk of anaphylaxis was also calculated based on both the number of administrations and clinically relevant repletion level of iron (1000 mg) achieved within 12 weeks.

Both analyses showed iron dextran was associated with the highest cumulative risk of anaphylaxis (82 per 100 000 persons, 95% CI, 70.5- 93.1) and iron sucrose with the lowest risk (21 per 100 000 persons, 95% CI, 15.3- 26.4).

 Iron dextran is no longer available in Australia. Iron polymaltose (Ferrum H [Aspen Pharmacare], Ferrosig [Sigma Pharmaceuticals]) and iron sucrose (Venofer [Aspen Pharmacare]) are the parenteral iron formulations currently available in Australia.