Crystallization in composite hydrogels

This study aims to control the dissolution of active pharmaceutical ingredients (API’s) in the human body through encapsulation in hydrogel matrices. In the case of class II pharmaceuticals (medicine with a low bioavailability), reducing the crystals to the submicron size can greatly enhance the dissolution rate and therefore the effectiveness of the API in the body. However, apart from the size, the polymorph of the API crystals also influences the solubility and dissolution rate. Therefore, control of both size and polymorphism of the nanocrystals is of vital importance. In our study we immobilize so called nanoemulsions of API solution in a hydrogel matrix and crystallize the API through evaporation of the solvent. Since the size of the crystals does not reach beyond the emulsion droplet size, controlling the droplet size means controlling the crystal size. Control over polymorphism is gained through the interplay of confinement and interactions between surfactant molecules at liquid-liquid interfaces. Among others, XRPD and DSC analysis are used for the identification of the crystal forms. Dissolution studies are performed to assess the performance of the produced composite particles.