HIGH-PERFORMANCE LIQUID CHROMATOGRAPHIC METHODS FOR THE DETERMINATION OF A NOVEL POLYMER-BOUND PACLITAXEL DERIVATIVE AND FREE PACLITAXEL IN HUMAN PLASMA

A high-performance liquid chromatographic (HPLC) assay has been designed for the quantitative determination of polymer-bound paclitaxel (after hydrolytic release of paclitaxel from the polymer) and free paclitaxel in human plasma after intravenous administration of the antitumor polymer-drug conjugate PNU166945. Chemical stabilization with 0.2 M ammonium acetate and solid-phase extraction (SPE) were required as sample pretreatment prior to the HPLC analysis. Separation was performed on an APEX Octyl analytical column and a mobile phase of acetonitrile-methanol-0.02 M ammonium acetate buffer pH 5.0 (4:1:5, v/v/v) and paclitaxel was detected at 227 nm. Total paclitaxel (polymer-bound pus free) levels were determined after chemical hydrolysis of the clinical samples with a mixture of 0.1 M KH2PO4 and methanol (1:1 v/v, pH 7.5) during 48 hours at room temperature. Concentrations of polymer-bound paclitaxel were calculated by subtraction of free from total drug levels. Plasma samples containing paclitaxel were...