High performance liquid chromatographic analysis of cilostazol in human plasma with on-line column switching

An analytical method of cilostazol, antiplatelet agent, in human plasma was developed using a semi-microbore HPLC equipped with an automated column switching system. After human plasma was diluted I : 2 with water and deproteinized, the fraction of analyte was injected onto a Capcell Pak MF Ph-1 column (20 mm x 4 mm I.D.). The cilostazol fraction was transferred from the MF Ph-1 column to an intermediate C-18 column (35 mm x 2 mm I.D.) using 10% acetonitrile in water at a flow-rate of 1 mL/min. The main separation was performed on a semi-microbore C 18 column (250 mm x 1.5 mm I.D.) using 40% acetonitrile in water at a flow-rate of 150 muL/min. The retention time of cilostazol was about 19 min. The limit of quantitative analysis was 25 ng/mL. The accuracy of the assay was from 93.94% to 115.54%, while the intra- and inter-day coefficient of variation (C.V.) of the same concentration range was less than 15%. The mean recovery was 98.9% and the responses were linear (r(2) > 0.999) over the concentration range of 25-2000 ng/mL. This analytical method showed excellent sensitivity, reproducibility, specificity, and speed using the plasma sample. This method could be suitable for the pharmacokinetic study of cilostazol in healthy volunteers, without time-consuming sample preparation after oral administration.