The aim of this study is to encapsulate ferrous sulfate in solid lipid nanoparticle (SLN) using a safe and efficient method for its protection against oxidation. A free organic solvent method as the melting lipid-double emulsion is used for SLN preparation. Ascorbic acid is employed for the prevention of drug oxidation. The appropriate ratio of compounds for SLN formation was modified using the pseudo-ternary phase diagram for the melted lipid, surfactant and internal water phase. The experimental design method is applied to achieve the best variables that can yield the lowest particle size and the highest drug entrapment efficiency. Entrapment efficiency and particle size of the optimum sample are 92.3% and 358 ± 21.9 nm, respectively. In addition, the drug release of optimum structure and the tablet form of ferrous sulfate in the phosphate buffer saline at pH = 7.4 reveal a higher and sustained drug release from SLN, which is nearly twice that of the free drug.

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