Munshi and Gawde: Development and Validation of a HPTLC method to Determine Serum Zonisamide Levels This investigation is aimed to develop and validate a high-performance thin layer chromatography method for quantitative determination of serum zonisamide levels. Chromatographic separation was carried out on a silica gel 60F254 plate using a mixture of ethyl acetate:methanol:toluene (4:1:5) as the mobile phase. Densitometric detection was carried out at 254 nm. The method was validated for linearity, precision, selectivity, limit of detection, limit of quantification and accuracy. Linear calibration curves in the range of 5 to 80 µg/band gave a correlation coefficient of 0.991. The intra-day (n=6) and inter-day (n=18) precision, expressed as the relative standard deviation were in the range of 2.83 to 3.27 % and from 2.09 to 4.39 %. The limits of detection and quantification were found to be 1.07 and 3.15 µg/band, respectively. Accuracy was calculated as percent recovery and was found to be 97.52 and 115.23 %. Theophylline was used as an internal standard, which gave a well separated peak at R f 0.36 without interfering with zonisamide. The method was found to be specific with no matrix interference. Thus, the method developed for the estimation of serum zonisamide level is simple, cost-effective and reliable for therapeutic drug monitoring.

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