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

Background: 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.

Objectives: 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.

Material and methods: 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).

Results: 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.

Conclusions: 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.