Preparation and characterization of floating drug delivery system of azithromycin

The objective of present study was to develop a stomach drug delivery system of azithromycin (AZH) as a model drug for eradication of Helicobacter pyloni (H. pylori). Floating microspheres of AZH were prepared by the solvent evaporation method. The prepared microspheres were subjected to evaluation for particle size, incorporation efficiency, in vitro buoyancy and in vitro drug release characteristics. The formulations were prepared at a variable stirring rate (300 to 500 rpm) and temperature (30-50 degrees C). Surface morphology characteristics were studied using scanning electron microscopy (SEM). The mean particle size of the microspheres significantly increased with increasing polymer concentration and was in the range 252.26 +/- 6.50 to 380.91 +/- 4.59 microm. Angle of repose was between 26.42 to 35.83 degrees. Tapped density ranged between 0.493 to 0.612 g/cm3. The compressibility index of all formulations was found to be in the range of 12.41 to 17.16%, which was < 20 indicating good flow characteristics. The encapsulation efficiency of the prepared microspheres was in the range of 27.8 +/- 4.30 to 66.23 +/- 2.08%. The physical state of the drug, before and after formulation was determined by differential scanning calorimetry (DSC). Percentage buoyancy of the microspheres was in the range 45.52 +/- 0.69 to 68.71 +/- 0.61% for 8 h. In vitro drug release studies were performed in simulated gastrointestinal fluid (SGF), pH 2.0 as dissolution medium (900 mL) for 8 h. Effects of stirring rate during preparation, polymer concentration and temperature on the size of microspheres and drug release were also observed. The results of the present studies indicated that the floating microspheres of AZH were formulated to provide site specific delivery of drug with a view to provide an effective and safe therapy for eradication of H. pylori with a reduced dose and reduced duration of therapy.