Preparation and In Vitro Evaluation of Budesonide Spray Dried Microparticles for Pulmonary Delivery

The present study describes development and in vitro evaluation of budesonide microparticles prepared by spray drying for delivering drug directly to lungs via dry powder inhaler. This paper introduces new formulations for pharmaceutical applications which includes conventional formulations and novel spray dried microparticles viz., pulmosols, microspheres and porous particles. Optimized spray drying parameters for generation of microparticles were: inlet temperature, 130 °C; outlet temperature, 80 °C; aspirator rate, 240 mWc (60%); solution feed rate, 2 ml/min; spraying air flow pressure, 2 bar. Microparticles appeared to be spherical, low-density particles characterized by smooth surface. MMAD and GSD ranged from 2.5–4.6 μm and 1.5–2.7 respectively. Effective index of microspheres (54.48) and porous particle formulations (64.22) was higher than the conventional formulation (49.21) indicating more effective deposition of microparticles to the lungs. Carr’s Index (20–30%) and Hausner ratio (1.2–1.7) for all formulations indicated good powder flow properties. Formulations emitted a fine particle fraction of 25–47%. Microparticles showed extended in vitro drug release upto 4 hours with high respirable fractions, thus use of microparticles potentially offers sustained release profile along with improved delivery of drug to the pulmonary tract.