High-performance liquid chromatographic analysis for the determination of a novel polymer-bound camptothecin derivative (MAG-camptothecin) and free camptothecin in human plasma

A selective HPLC assay is described for the determination of free and total (free plus polymer-bound) camptothecin (CPT) in human plasma after adminis tration of the anti-tumor drug MAG-CPT (polymer bound camptothecin). Total CPT levels were determined after hydrolysis and free CPT was extracted from acidified plasma using Oasis solid-phase extraction material. Extracts wer e analyzed on a Zorbax SB-C-8 analytical column, using a mixture of acetoni trile-25 mM phosphate buffer (pH 4.0) as the eluent. Detection was performe d fluorimetrically. Concentrations of polymer-bound CPT were calculated by subtraction of free from total CPT. The lower limits of quantitation of the methods were 100 ng/ml for total and 1.0 ng/ml for free CPT using 50 mul a nd 250 mul plasma, respectively. Special attention was paid to the stabilit y of the analytes. The presented method was successfully applied in a clini cal pharmacokinetic study in our institute. (C) 2001 Elsevier Science B.V. All rights reserved.