Validation of a High-performance Liquid Chromatographic Assay Method for Quantification of Total Vincristine Sulfate in Human Plasma Following Administration of Vincristine Sulfate Liposome Injection

The validation of a high performance liquid chromatographic (HPLC) assay method for quantitation of total vincristine sulfate (VINC) in human plasma is described. VINC was extracted from plasma using BondElut CBA solid phase cartridges with vinblastine as the internal standard. Chromatography was accomplished using a Waters Symmetry C8 (250 mm x 4.6 mm i.d.) analytical column, a Waters Delta-Pak ODS guard column with a mobile phase of 34.9% water-0.1% diethylamine (pH 7.0)-40% acetonitrile-25% methanol pumped isocratically at 1.0 ml min(-1) with ultraviolet detection at 297 nm. Above the limit of quantitation of 28.6 ng ml(-1), the area ratio precision (R.S.D. range 3.33-11.6%) and accuracy of predicted values (R.S.D. range 8.56-23.8% with the limit of quantitation being the only value above 20%) were acceptable. The assay was linear from 28.6-2860 ng ml(-1) VINC in plasma. Recovery of VINC from plasma and VINC from plasma spiked with vincristine sulfate liposome injection ranged from 74.9-87.1%. Stability of VINC in plasma stored at -20 degrees C for at least 49 days and of extracted plasma samples was demonstrated. Potential interference in quantitation of VINC from commonly co-administered drugs was evaluated along with day-to-day variability. The assay procedure was found suitable for evaluation of VINC clinical pharmacokinetics in plasma following administration of vincristine sulfate liposome injection prepared using distearoylphosphatidylcholine (DSPC)/cholesterol liposomes for injection.