Application of Box-Behnken Design for Validation of High-Per- Formance Thin-Layer Chromatography/Densitometry Method for Robustness Determination of Apremilast in Bulk and inhouse Tablets
Background: Apremilast is small molecule inhibitor of phosphodiesterase- 4 (PDE-4) and an immunomodulating agent which is used for management of refractory psoriatic arthritis. Material and Methods: High- Performance Thin-Layer Chromatography (HPTLC) method for the analysis of apremilast was developed and validated as per ICH guidelines. Apremilast was chromatographed on silica gel 60 F254 TLC plates using toluene: methanol (8:2 v/v) as a mobile phase. A Compact spot for apremilast was observed with Rf 0.64 ± 0.05, when the densitometric scanning was implemented at 230 nm. The linear regression analysis data for the calibration plots showed r2 > 0.99 with a concentration range from 250 – 1500 ng/band. ‘Design of Experiments’ (DoE) employing ‘Box-Behnken Design’ (BBD) and ‘Response Surface Methodology’ (RSM) were studied as an advancement to traditional ‘One Variable at Time’ (OVAT) approach to assess the effects of variations in selected factors particularly (development distance, saturation time, activation time of plate and mobile phase ratio) as graphical interpretation for robustness. The statistical insight was achieved with Multiple Linear Regression (MLR) and ANOVA. Results: The method was validated for precision, accuracy, detection limit and quantitation limit, and robustness. Conclusion: The method was successfully employed for the determination of apremilast from its in-house tablet formulation.