Validated HPLC-DAD method for stability study of sulbutiamine HCl

Abstract

Sulbutiamine (SUL) is a synthetic thiamine derivative widely used for treatment of memory disorders. In this study, a newly developed gradient HPLC-DAD method demonstrating no interference from the different degradation products of SUL has been optimized and validated. The drug was subjected to variable stress conditions including hydrolysis (at different pH values), oxidation, photolysis and dry heat. The drug was found to be labile to hydrolysis, oxidation and photolysis but stable in thermal and neutral hydrolytic degradation. Successful chromatographic separation of SUL from all degradation products with significantly different t_R values was achieved on a ZORBAX Eclipse Plus C18 column using a mobile phase containing a gradient mixture of solvent A (50 mM KH₂PO₄ (pH 3.6 ± 0.2)) and solvent B (methanol). UV detection was performed at 254 nm using a photodiode array detector (DAD). The reliability of the method was assessed by evaluation of accuracy, precision, specificity, robustness and ruggedness according to USP guidelines. The linear regression analysis data for the calibration curve showed a good relationship in the range of 2–40 μg mL⁻¹. System suitability tests were performed, and selectivity (α) and resolution (R_s) factors were found to be greater than 1.5 and 2, respectively. The assay method was successfully used to estimate SUL in Arcalion Forte® tablets and good percentage recoveries were obtained. The developed method compared favorably with the reported spectrophotometric method.