Preparation and Optimization of Immediate Release/Sustained Release Bilayered Tablets of Loxoprofen Using Box–Behnken Design

The aim of our current study was to characterize and optimize loxoprofen immediate release (IR)/sustained release (SR) tablet utilizing a three-factor, three-level Box–Behnken design (BBD) combined with a desirability function. The independent factors included ratio of drug in the IR layer to total drug (X₁), ratio of HPMC to drug in the SR layer (X₂), and ratio of Eudragit RL PO to drug in the SR layer (X₃). The dependent variables assessed were % drug released in distilled water at 30 min (Y₁), % drug released in pH 1.2 at 2 h (Y₂), and % drug released in pH 6.8 at 12 h (Y₃). The responses were fitted to suitable models and statistical validation was performed using analysis of variance. In addition, response surface graphs and contour plots were constructed to determine the effects of different factor level combinations on the responses. The optimized loxoprofen IR/SR tablets were successfully prepared with the determined amounts of ingredients that showed close agreement in the predicted and experimental values of tablet characterization and drug dissolution profile. Therefore, BBD can be utilized for successful optimization of loxoprofen IR/SR tablet, which can be regarded as a suitable substitute for the current marketed formulations.