Evaluation and optimization of preparative variables for controlled-release floatable microspheres prepared by poor solvent addition method

The aim of this study was to evaluate and optimize preparative parameters for floatable theophylline microspheres prepared by the emulsion-solvent evaporation method. A three-factor three-level Box-Behnken design was employed using amount of poor solvent, temperature-increase rate and drug loading as independent factors, and percentage floating at 3 h and time required for 50% drug release as dependent variables. Simultaneous optimization of the parameters for maximum buoyancy and desirable drug release was conducted using a partitioned artificial neural network. A microsphere using 27.6% of drug loading, 0.29 degrees C/min of temperature-increase rate, and 1.7 mL of poor solvent was identified for maximizing buoyancy and sustaining drug release.