How Do Cryo-Milling and Lyophilization Affect the Properties of Solid Dispersions with Etodolac?

Background: Solid dispersions (SDs) of etodolac (ETD), a poorly water-soluble drug model, were developed to enhance its solubility and dissolution rate by employing various preparation methods and hydrophilic or amphiphilic polymers. Methods: Polyvinylpyrrolidone-poly(vinyl acetate) copolymers (PVP/VA), hydroxypropyl methylcellulose (HPMC) and poloxamer were used as carriers, while cryo-milling and lyophilization were utilized as routine methods to SDs preparation. Obtained SDs were characterized by drug content, solubility, dissolution rate and moisture content. The physical structure of SDs was estimated via scanning electron microscopy (SEM), whereas differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR) were employed to assess the potential drug-carrier interactions. Results: SD formulations demonstrated enhanced solubility of ETD in aqueous media, including water and buffers (pH 5.5 and 7.4). DSC analysis confirmed that PVP/VA and poloxamer ensured better ETD dissolution and protection against recrystallization. Furthermore, FTIR indicated the formation of hydrogen bonds between ETD and polymer, particularly in lyophilized dispersions. Conclusions: The optimized SD formulation for ETD contained PVP/VA and/or poloxamer as carriers and was obtained via lyophilization. This SD formulation exhibited the most favorable properties, enhanced the solubility and dissolution of ETD in aqueous media and effectively reduced its crystallinity.