Abstract

A floating drug delivery system of piroxicam in the form of microspheres was prepared using an enteric polymer and emulsification solvent-evaporation method. The microspheres remained buoyant continuously over the surface of acidic media containing surfactant for a period of 8-12 h in vitro . Differential scanning calorimetry and X-ray diffraction studies showed that drug incorporated in the outer shell of the polymer was completely amorphous. Scanning electron micrographs indicated that the microsphere is perfect sphere with an internal hollow cavity enclosed by a rigid shell of polymer. The micromeritic properties of microspheres were found to be much improved compared with original drug crystals. The in vitro drug release behavior of the floating microspheres was characterized as an enteric property. Polymer being soluble above pH 7.0, the drug release rates from microspheres changed dramatically above and below pH 7.0. At intestinal pH the drug release was faster and continuous as compared to the amount released at gastric pH.