Kinetic evaluation of Arbutin hydrolysis and its possible interference in hydroquinone assay methods for topical formulations according to United states Pharmacoepia

Abstract

Background: Evaluation of drugs stability in stress conditions analytical methods is very important in industrial pharmacy. Aim: The purpose of this study is to investigate the kinetic of arbutin hydrolysis and to evaluate its possible interference with the USP pharmacopeial methods of hydroquinone assay in topical preparations. Materials and Method: The hydrolytic stress conditions were optimized with screening tests. The standard concentrations of Arbutin were stored at acidic pH at 50 ° C and then the remaining drug and the degradation products were evaluated by HPLC PDA method. Data were fitted to different kinetic models. The possible interference of Arbutin in the assay of hyroquinone with USP method was evaluated using standard concentrations of Arbutin and Hydroquinone using UV method Results: According to HPLC analysis for the three drugs; arbutin, hydroquinone and benzoquinone, the utilized system was suitable, valid and stability indicating. The hydrolytic degradation of Arbutin followed the aero order kinetic. The interference of Arbutin in the pharmacopeial USP method was proved. Conclusion: The hydrolytic degradation of Arbutin resulted in the formation of two products; hydroquinone and benzoquinone. In this study a simple HPLC method with isocratic elution with UV detection for the simultaneous quantification of Arbutin, Hydroquinone and benzoquinone was introduced. The stability indicating ability of this method in the determined stress condition was also proved. The acidic hydrolysis of Arbutin was not depebdent to its initial concentration. The interference of Arbutin in Hydroquinone UV assay should be considered especially in the cosmeceutical preparations formulated with the both actives together.