RP-HPLC METHOD FOR THE SIMULTANEOUS ASSAY OF METFORMIN AND BENFOTIAMINE: DEVELOPMENT AND VALIDATION

A sensitive, precise and accurate reverse phase high performance liquid chromatographic method (RP-HPLC) using an isocratic elution of 0.1 M NaH₂PO₄ (pH 3.0) and acetonitrile (80:20 v/v) with a flow rate of 1.0 mL/min, a column temperature of 30 °C and UV detection at 254 nm was developed for the estimation of metformin and benfotiamine simultaneously. The method was validated following guidelines given by International Conference Harmonization. The method allowed the determination of metformin and benfotiamine in the concentration range of 100-300 μg/mL and 15-45 μg/mL, respectively. The limit of detection & limit of quantification were 0.290 μg/mL & 0.968 μg/mL for metformin and 0.047 μg/mL & 0.156 μg/mL for benfotiamine, respectively. The percent relative standard deviation (%RSD) value was 0.067 % for metformin and 0.047 % for benfotiamine. The accuracies were 99.510 – 99.797% and 9.652 – 99.890% for metformin and benfotiamine, respectively. The developed and validated RP-HPLC method was applied successfully for the quantification of metformin and benfotiamine simultaneously in tablet dosage form. Common excipients in the tablet dosage form did not interfere with the assay of metformin and benfotiamine. Hence, the proposed RP-HPLC method is suggested for routine analysis of metformin and benfotiamine in quality control laboratories.