Sensitive HPLC method for quantitation of paclitaxel (Genexol®) in biological samples with application to preclinical pharmacokinetics and biodistribution

A sensitive, specific and reproducible HPLC method has been developed and validated for the quantitative determination of paclitaxel in plasma, tissues and tumor of mice. Tissue specimens including liver, kidneys, spleen, lungs, heart and tumor were separately homogenized in bovine serum albumin (BSA, 40 g/l) in water. Plasma or tissue homogenates (0.1 ml) containing paclitaxel and internal standard (dimethyl-4,4′-dimethoxy-5,6,5′,6′-dimethylene dioxy biphenyl-2′,2′ dicarboxylate (DDB), I.S.) were extracted by ethyl acetate (10 ml). A 4.6 mm × 250 mm ODS column was used to separate the components in biological samples with UV detection at 227 nm and gradient system was applied to a quantitation of paclitaxel consisting of acetonitrile-deionized water. The I.S. and paclitaxel were eluted at 13.7 and 18.0 min, respectively, and no interfering peaks were observed. Linear relationships (r2 > 0.999) were obtained between the peak height ratios and the corresponding biological sample concentrations over the range of 0.1-20 μg/ml. The average intra- and inter-day variations (% R.S.D.s and % deviations) of the assay for biological samples were less than 10%. The LOD and LOQ were 5 and 10 ng/ml, respectively, for paclitaxel using a microsample volume (100 μl) of plasma sample. This HPLC method has been successfully applied for the determination of paclitaxel in pharmacokinetic and biodistribution study in after administration of 50 mg equivalent paclitaxel/kg dose of paclitaxel-loaded polymeric micelle and 20 mg equivalent paclitaxel/kg dose of Taxol® to female SPF C57BL/6 mice.