Particular film formation of phenytoin at silica surfaces

Given the increasing number of poorly soluble and thus poorly bioavailable active pharmaceutical materials, there is a demand for innovative formulation platforms for such molecules. Thus a focus on enhancing dissolution properties of poorly soluble drugs exists. Within this study, the spin coating of acetone solutions containing 5,5-diphenyl-2,4-imidazolidinedione (phenytoin) in various concentrations is evaluated. The results reveal strong variations of the morphology of deposited phenytoin crystals at silica surfaces. Individual separated particles are obtained on low phenytoin concentrations, and closely packed particular films form when the concentration is increased. As the material is isomorphic, these various morphologies have the same crystalline structure. Dissolution experiments reveal that both the apparent maximum solubility and as the dissolution rate are strongly enhanced compared to bulk powder, suggesting that formulation based on this preparative technique will allow overcoming the low solubility problematic for a variety of drugs.