Development and evaluation of a sustained release solid dispersion of cefdinir using a hydrophobic polymeric carrier and aminoclay

This study aimed to develop a sustained release formulation of cefdinir using a blended mixture of an insoluble and low-permeability polymer and aminoclay, a cationic nanosheet. Sustained release solid dispersions (CSD1–CSD7) were prepared using a solvent evaporation method at the various drug and excipient ratios. Based on the dissolution characteristics, the optimal formulation (CSD6) was selected as the weight ratio of cefdinir:Eudragit® RS PO:aminoclay of 1:4:0.01. In a buffer transition system, the CSD6 formulation exhibited gradual drug release over the pH range of 1.2–6.8, achieving approximately 75% drug release over 12 h. The sustained drug release profile of the CSD6 formulation was also well maintained in simulated intestinal fluids in fasted and fed states, implying that the effect of food intake on the drug dissolution might be insignificant. The structural characterization of the CSD6 formulation was carried out using powder X-ray diffraction and differential scanning calorimetry and suggests that the drug crystallinity was changed to an amorphous form in CSD6. In addition, when orally administered to rats, the CSD6 formulation showed sustained drug release with longer T_max but lower C_max, compared to pure cefdinir. These results indicate that the CSD6 formulation is a promising approach for reducing the dosing frequency of cefdinir via the sustained drug release.