Quantitative analysis of repaglinide in tablets by reversed-phase thin-layer chromatography with densitometric UV detection

A simple, rapid, and stability-indicating thin-layer chromatographic method has been developed for quantitative determination of repaglinide in tablets. Analysis was performed on RP-8 TLC plates with acetonitrile-pH 6.0 phosphate buffer, 60 + 40 (% v/v), as mobile phase. Detection and quantification were performed by classical densitometry at the wavelength of maximum absorption of repaglinide, 225 nm. A calibration plot constructed in the range 0.6-3.6 mu g/10 mu L was linear with a good correlation coefficient (r = 0.998 +/- 0.001, mean +/- SD, n = 5). Limits of quantitation and detection of repaglinide were 0.27 mu g/10 mu L and 0.08 mu g/10 mu L, respectively. Instrumental precision established at three concentrations of the drug ranged from 3.92 to 0.97% for the lowest and highest concentrations of repaglinide, respectively. The mean intra-day and inter-day variability, including three concentrations of repaglinide, were 1.93 and 2.25% (n = 9), respectively. Recovery from model mixtures, at three levels of addition, ranged from 103.06 to 102.49% for the lowest and highest levels, respectively. Total mean SD recovery was 102.71 +/- 2.04% (n = 15). The mean SD recovery from commercially available tablets was 101.85 +/- 1.83% (n = 10). The effect of pH, temperature, and UV light on degradation of repaglinide was also investigated. The analytical method presented was found to be simple, reliable, and convenient for routine pharmaceutical analysis. Its analytical performance fulfilled acceptance criteria established for TLC methods in the official literature.