Sol-gel processing of anti-inflammatory entrapment in silica, release kinetics, and bioactivity

Controlled and local drug-delivery systems for anti-inflammatory agents are drawing increasing attention for possible pharmaceutical and biomedical applications, because of their extended therapeutic effect and reduced side effects. A single-step sol-gel process was used to precipitate silica microspheres containing Ketoprofen, Indomethacin, Ketorolac tris salt, or Triamcinolone acetonide, for controlled drug delivery applications. The amorphous nature of the gels was ascertained by X-ray diffraction analysis. Release kinetics in a simulated body fluid (SBF) has been subsequently investigated. The amount of drug released has been detected by UV-vis spectroscopy. The pure anti-inflammatory agent exhibited linear release with time, while sol-gel silica-entrapped drugs were released with a logarithmic time dependence, starting with an initial burst effect followed by a gradual decrease. Finally, SEM micrography and EDS analysis showed the formation of a hydroxyapatite layer on the surface of the samples soaked in SBF. All the materials showed good release and therefore could be used as drug-delivery systems. (C) 2008 Wiley Periodicals, Inc. J Biomed Mater Res 87A: 843-849, 2008