Preparation and characterization of atenolol-loaded cellulose acetate butyrate-poly(vinyl pyrrolidone) blend microspheres:: in vitro release studies

Cellulose acetate butyrate-poly(vinyl pyrrolidone) (CAB-PVP) blend microspheres were prepared using the solvent evaporation technique using poly(vinyl alcohol) as an emulsifying agent. Atenolol (ATNL), an antihypertensive drug, was successfully loaded into these microspheres. Effect of experimental variables such as CAB/PVP ratio on ATNL encapsulation efficiency, release rate, size and morphology of the microspheres has been investigated. ATNL-loaded microspheres were analyzed using differential scanning calorimetry to investigate the crystalline nature of ATNL after encapsulation. DSC results indicated a non-uniform dispersion of ATNL in CAB-PVP blend matrix. Scanning electron micrographs indicated the formation of spherical microspheres. Mean particle size of the microspheres, as measured by the laser light scattering technique, ranged between 100 and 120 pm. An encapsulation of about 80% of ATNL was achieved. In vitro dissolution experiments performed in pH 7.4 buffer medium indicated the controlled release of atenolol from the blend microspheres up to 10 h.