Design of experiment avenue for development and validation of RP-HPLC-PDA method for determination of apremilast in bulk and in in-house tablet formulation

Abstract Background Apremilast is phosphodiesterase-4 and an immunomodulating agent used for treatment of refractory psoriatic arthritis. Methods The reversed-phase high-performance liquid-chromatography method for analysis of apremilast was developed and validated as per ICH guidelines. The separation of apremilast was performed on PrincetonSPHERE Ultima C18 column (250 mm × 4.6 mm, i.d., 5 μm particle size) with photodiode array detection carried out at 231 nm. A Box–Behnken design with response surface methodology was executed out for optimization of chromatographic conditions of reversed-phase high-performance liquid-chromatography for finished desired chromatographic separation of apremilast from its formulation with less number of experimental trials. Three independent factors, namely methanol composition in the mobile phase, pH of an aqueous phase, and flow rate, were used to construct a mathematical model and study the effects of these independent factors on responses such as retention time, theoretical plates, and tailing factor. Results Optimized experimental conditions for proposed work consists of methanol and water, pH 3.50 adjusted with ortho-phosphoric acid (70:30 % v/v) as a mobile phase at a flow rate 1 ml/min with a retention time was found to be 5.15 min. Accuracy study was completed at three different levels and was found in the range of 99.44–101.49%. Conclusion The 3D response surface graphs revealed that the methanol composition and pH of an aqueous phase were both most stringent factors affecting the responses. Thus, a new, precise, and accurate HPLC method was developed and validated and can be used for regular analysis of apremilast