Validated Stability-Indicating Spectrofluorimetric Method with Enhanced Sensitivity for Determination of Repaglinide in Tablets

A simple and highly sensitive spectrofluorimetric method was developed and validated for determination of the antidiabetic agent repaglinide (RG) in tablets. The proposed method is based on measurement of the native fluorescence of RG in 0.1 M H2SO4/methanol medium at 360 nm after excitation at 243 nm. The method showed a linear dependence of the relative fluorescence intensity on drug concentration over the range of 0.02-0.50 mu g mL(-1) with lower detection limit of 6.0 ng mL(-1) and lower quantification limit of 18 ng mL(-1). The method was successfully applied for determination of RG in different tablets and the obtained results were in good agreement with those obtained by the official method. The proposed method was extended to investigate the kinetics of oxidative degradation of the drug. A proposal for the degradation pathway was postulated.