Encapsulation of antihypertensive drugs in cellulose-based matrix microspheres: characterization and release kinetics of microspheres and tableted microspheres

This study is an attempt to prepare microspheres loaded with two antihypert ensive drugs viz., nifedipine (NFD) and verapamil hydrochloride (VRP) using cellulose-based polymers viz., ethyl cellulose (EC) and cellulose acetate (CA). Emulsification and solvent evaporation methods were optimized using e thyl acetate as a dispersing solvent. The particles are spherical in shape and have smooth surfaces, as evidenced by the scanning electron microscopy. The microspheres were characterized for their particle size and distributi on, tapped density and encapsulation efficiency. Smaller sized particles wi th a narrow size distribution were produced with EC when compared to CA mat rices. Molecular level drug distribution in the microspheres was confirmed by differential scanning calorimetry. The microspheres were directly compre ssed into tablets using different excipients. The drug release from CA was faster than EC microspheres and, also, the VRP release was faster than NFD. The excipients used in tableting showed an effect on the release as well a s the physical properties of the tablets.