Hollow crystal anti-solvent preparation process as a promising technique to improve dissolution of poorly soluble drugs

Innovative results using the anti-solvent preparation process to obtain hollow crystals of Deflazacort (DFZ) and Carbamazepine (CBZ) with improved dissolution characteristics are presented. DFZ is a methyloxazoline which is prefered over other corticosteroids due to its major advantages and performance. CBZ is a well-established drug for epilepsy treatment and exhibits at least four polymorphic forms and hydrate or solvate forms. Both drugs are poorly soluble in water and several strategies have been developed in order to find preparation methods to improve their dissolution rates. Moreover, reports have shown high dissolution variability in the tablets of DFZ and CBZ currently on the market. In this work, the hollow crystals of DFZ and CBZ were crystallized and characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRD), thermal analysis (DSC) and diffuse reflectance infrared Fourier (DRIFT) spectroscopy. DFZ showed prismatic hollow crystals with the same crystal structure of the raw material. The morphology of crystallized samples of CBZ showed the same shape; however, the raw material was a monoclinic form (polymorph III) while hollow crystals presented triclinic crystal structure (polymorph I). Finally, in both cases, the hollow crystals of CBZ and DFZ significantly improved the dissolution properties in comparison with the initial raw materials. ► We obtained hollow crystal habits of CBZ and DFZ by antisolvent method. ► Hollow crystal of CBZ presented a polymorphic modification and DFZ the same crystal structure. ► Hollow crystals presented a significant increase in dissolution performance. ► Our results demonstrated the relevance of the design and control of the morphology of APIs. ► Obtaining hollow crystal is a promising strategy to improve the dissolution properties.