Quantitative Determination of Topiramate in Human Breast Milk

A thin-layer chromatographic (HPTLC) method for quantification of topiramate in human breast milk was developed using liquid –liquid extraction with n-hexane and methanol as extraction solvents, fluorescence activation with ninhidrine (1% ethanolic solution) and chlorpromazine as internal standard. Thin-layer chromatographic separation was performed on precoated silica gel F 254 HPTLC plates using a mixture of toluene: ethanol (25:10, v/v), as mobile phase. Densitometric detection was done at 326 nm. The method was validated for linearity, precision, selectivity, LOD and LOQ, and accuracy. Linear calibration curves in the range of 0.30 to 50.00 µg/mL showed correlation coefficient of 0.991. The intra-assay and inter-assay precision, expressed as the relative standard deviation (RSD), were in the range of 3.04% - 3.14% (n=3) and 1.81%-4.10% (n=9), respectively. The limit of detection was 0.24 µg/mL, and the limit of quantification was 0.30 µg/mL Accuracy, calculated as percentage recovery, was between 101.65% and 109.51%, with a RSD not higher than 0.41%. Topiramate is well resolved from others antiepileptic drugs and from the internal standard (Rs=5.20). In conclusion, the method is precise, accurate, reproducible and selective for the analysis of topiramate in human breast milk.