Preparation, characterization and in vitro evaluation of tablets containing microwave-assisted solid dispersions of apremilast

Solid dispersions are among the techniques successfully employed to enhance the dissolution of poorly water-soluble drugs. Microwave (MW)-assisted evaporative crystallization has been used to prepare solid dispersions of drugs and polymers. The aim of the study was to investigate the solubility of apremilast (APM) in water by exploring the effect of MW-assisted solid dispersion technology. In the present study, solid dispersions of APM, a poorly water-soluble drug, were prepared. The solid dispersions were prepared using the conventional method (CM) and the MW-based solvent evaporation technique. Microwave energy was used to enhance the solubility and dissolution rate of APM. The physical mixture and solid dispersions were characterized using Fourier-transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). Apremilast tablets containing MW-assisted solid dispersions were prepared by the direct compression technique and compared with the marketed formulation (Aprezo tablets). The results obtained confirmed the conversion of crystalline APM to an amorphous form. The XRPD pattern of the MW-assisted formulation at a 2:1 ratio suggests the amorphous structure of APM within the formulation. Based on solubility studies results, Syloid® 244FP was selected as the best carrier. The dissolution study results suggested that the APM tablet prepared using MW-assisted solid dispersions at a 2:1 carrier/drug ratio improved the APM dissolution rate compared to the marketed formulation. Based on the results, it can be concluded that the MW-assisted solid dispersion technique may be an effective approach to enhancing the dissolution profile of other poorly water-soluble drugs.