Evaluation of Different Polysaccharide–Iron Complex Preparations In Vitro and In Vivo

Objectives: Iron-deficiency anemia is one of the most common nutritional deficiencies worldwide. Polysaccharide–iron complexes (PICs), as novel organic iron supplements, have garnered increasing attention due to their high bioavailability, minimal gastrointestinal irritation, and favorable tolerability. However, different formulations of PICs can show significant variations in their physicochemical properties and bioavailability. These factors are crucial for clinical efficacy and safety. Methods: This study selected two formulations of polysaccharide–iron complexes: Formulation A (PIC-coated pellets) and Formulation B (PIC powders), with ferrous succinate tablets (Formulation C) used as a control. The focus was on evaluating the molecular weight of the polysaccharides, the levels of free iron, and the dissolution across various dissolution media. Physicochemical properties were compared through particle size analysis, dissolution rate testing, and free iron content determination. Additionally, the pharmacokinetic properties of the two PIC formulations were assessed in a beagle dog model of iron-deficiency anemia. Results: Significant differences were observed in particle appearance and content structure between the two PIC formulations. Formulation A, prepared using pellet technology, exhibited a uniform particle size distribution. Its dissolution rate in acidic environments was significantly lower than that of Formulation B. In simulated gastric fluid, the cumulative iron dissolution rate of Formulation A was less than 15% within two hours, while that of Formulation B exceeded 50%, with substantial batch-to-batch variability. In various dissolution media, Formulation A released 12% of its dissolved iron content in gastric fluid within two hours. In contrast, the absolute free iron content of Formulation B was 8.5 times higher than that of Formulation A in simulated gastric fluid. In the beagle dog model of iron-deficiency anemia, Formulation A showed significantly higher bioavailability, which suggests that the pellet preparation technology improves both the acid resistance and bioavailability of the PIC formulation. Conclusions: The study revealed that Formulation A, prepared using pellet technology, possesses unique quality characteristics. This technology significantly reduces the release of free iron from PICs due to gastric acid action, potentially minimizing gastrointestinal irritation. Moreover, the pellet preparation process improves the acid resistance and bioavailability of PIC formulations, offering a more effective therapeutic option for iron-deficiency anemia. Future research may further explore the potential applications of pellet technology in other iron supplement formulations.