Development of HPLC method for the determination of levosulpiride in human plasma

A rapid and simple high performance liquid chromatography (HPLC) method was developed and validated for determination of levosulpiride in human plasma. After extraction with ethylacetate/methylene chloride (5:1, v/v), analysis of levosulpiride in plasma samples was carried out using a reverse phase C18 column with fluorescence detector (maximum excitation at 300 nm and maximum emission at 365 nm) for separation and quantification. A mixture of methanol-20 mM phosphate buffer (pH 3.5, 16:84, v/v) was used as a mobile phase. The method was specific and sensitive with a limit of quantification of 5 ng/ml. This HPLC method was validated by examining the precision and accuracy for inter- and intra-day analysis in the concentration range of 5-150 ng/ml. The relative standard deviation (R.S.D.) in inter- and intra-day validation were 8.16-19.75 and 3.90-11.69%, respectively. In stability tests, levosulpiride in human plasma was stable during the storage and assay procedure. The method was applied to the bioequivalence study of two levosulpiride tablet formulations (25 mg) after a single oral administration.