Preparation, characterization and in vitro release kinetics of aminophylline loaded albumin microspheres

Abstract

Aminophylline loaded albumin microspheres were prepared by emulsion polymerization technique varying the drug-protein ratio, stabilizing temperature and stirring speed The mean diameter of the particles increased and drug loading decreased with increasing protein concentration. The drug loading was more in microspheres prepared at low stabilization temperature and stirring speed. Scanning electron microscopy revealed that microspheres prepared at higher temperatures were spherical and smooth. The particle size decreased with increase in the stirring speed. The slowest in vitro drug release was obtained from microspheres prepard at the highest stabilization temperature of 160°C and the lowest stirring speed of 500 r.p.m. The biphasic release profile was analysed for different kinetic models. The best fit for initial phase was obtained from Higuchi's √t equation and for terminal phase from first order kinetics. An optimum condition for synthesis of aminophylline loaded albumin microspheres suitable for passive targeting to lung was determined.