Cloud-Point Extraction Coupled with High-Performance Liquid Chromatography for the Determination and Pharmacokinetic Study of Dipyridamole in Rat Plasma

Background: A straightforward and environment-friendly high-performance liquid chromatography/ diode array detection (HPLC/DAD) method based on cloud-point extraction (CPE) was developed for the determination of dipyridamole in rat plasma after oral administration. Methods: The non-ionic surfactant Triton X-114 was chosen as the extract medium. Various parameters affecting the CPE efficiency were evaluated and optimized. Separation was obtained using a reversedphase Zorbax SB-C-18 column (250 x 4.6 mm, 5 mu m) at 30 degrees C with detection wavelength at 292 nm. Results: Under the optimum conditions, the assay was linear over the concentration range of 0.1-20.0 mu g mL(-1) with the regression coefficients greater than 0.998, and the lower limit of quantification (LLOQ) was 0.1 mu g mL(-1). The extraction recoveries were more than 83.1%, the accuracies were within +/- 9.7%, and the intra-day precision below 5.4% and inter-day precision below 12.6% in all cases. Conclusion: The validated method is convenient, rapid and accurate for the pharmacokinetic study of dipyridamole in rat after oral administration.