New insight on prednisolone polymorphs in mesoporous silica/maghemite nanocomposites

Abstract

Prednisolone loaded mesoporous silica nanocomposites with different amounts of maghemite core were prepared to design a drug delivery system suitable for drug administration in magnetic field. Textural investigations evidenced that 80–150 nm sized spherical particles with 3–3.5 nm pore size are formed by the applied synthesis method, varying with the amount of incorporated magnetic particles. Mössbauer spectroscopic results proved the presence of small maghemite nanoparticles inside the silica structure. Fourier transform infrared and Raman spectroscopic measurements provided data about the interaction between the drug and the silica, and revealed the polymorphic nature of prednisolone. Spectroscopic data suggested weak bonding between silanol groups of the mesoporous silica nanoparticles and prednisolone molecules. By the applied drug loading method polymorphic transformation of the parent Form I prednisolone occurred. In vitro release process at pH 7 showed lower solubility of polymorphic Form II compared to Form I. Slower release of prednisolone was observed by silica loaded formulations, reaching total amount in 10 h. The effect of prednisolone polymorphs loaded in silica carrier on its pharmacokinetic properties was studied for the first time.