Stability Assessment of Intravenous Iron–Carbohydrate Complexes in Commercial All-in-One Parenteral Nutrition: Potential for Therapeutic Iron Dose Admixing

<b>Background/Objectives:</b> Iron deficiency and associated iron deficiency anaemia represent a major global health burden. Parenteral nutrition (PN) patients are at increased risk of iron deficiency due to inadequate iron supplementation. Currently, iron is added to all-in-one (AIO) PN mostly as low-dose ferric chloride in trace element solutions, limited to 1-2 mg in adults, to ensure emulsion stability and prevent lipid peroxidation. The objective of this study was to evaluate the compatibility and stability of selected, widely used complex-bound iron products added to AIO PN over a 48 h period. <b>Methods</b>: Ferric carboxymaltose and iron sucrose were added as non-biological complex intravenous iron oxide carbohydrate products to two different commercial AIO PN admixtures for adults. The iron concentrations used were 100 and 400 mg/L (1.79 and 7.16 mmol/L), corresponding to approximately 200 mg (3.58 mmol) of iron dose per PN bag. Free and complex-bound iron were separated using 100 kDa dialysis tubes. Free and complex-bound iron were assessed at 4, 24, and 48 h after admixing. pH was measured before and at 0, 4, 24, and 48 h after admixture. Iron quantification was performed by inductively coupled plasma mass spectrometry (ICP-MS). <b>Results</b>: No significant changes in complex-bound iron concentration were observed over the 48 h incubation period (<i>p</i>-value = 0.449; estimate 0.060 mg/L per h, 95% CI -0.089, 0.201 mg/L per h). The concentration of free iron was very low and increased only slightly over time. Iron recovery ranged from 95.8% to 103.9%. The addition of the alkaline iron sucrose significantly increased the pH of the AIO admixture (<i>p</i>-value = 0.033), whereas the addition of ferric carboxymaltose did not affect the pH (<i>p</i>-value = 0.351). After the initial increase, the pH of all conditions remained stable over the 48 h incubation period (<i>p</i>-value = 0.07). <b>Conclusions</b>: Ferric carboxymaltose demonstrated stable intravenous iron admixtures within the PN formulations tested. Before the clinical application of these findings, further studies should specifically evaluate the lipid peroxidation and stability of the lipid emulsions, the most sensitive and important PN compatibility and safety characteristics of AIO PN.