COMPARISON OF FILTER AND TUNABLE FLUORESCENCE DETECTION FOR THE HPLC SIMULTANEOUS QUANTITATION OF LACTONE AND CARBOXYLATE FORMS OF TOPOTECAN IN PLASMA

The hydrolysis of the alpha-hydroxy-delta-lactone ring moiety in topot ecan is routinely monitored using high performance liquid chromatograp hy (HPLC) with fluorescence detection. While both tunable and filter f luorescence detectors are commercially available, only the tunable det ector has been studied for clinical and in vitro applications of topot ecan. In the present study we have developed a simple HPLC method for the simultaneous separation of the lactone and carboxylate forms of to potecan in plasma, which, can be utilized for both clinical and in vit ro studies. Limits of detection, percent relative standard deviation, and linear range for both the lactone and carboxylate forms of the dru g in plasma are presented and compared using a tunable and filter fluo rescence detector. Limits of detection in plasma of 0.10 ng/mL for car boxylate and 0.26 ng/mL for lactone have been obtained using a tunable fluorescence detector. A filter fluorescence detector produced limits of detection of 0.15 ng/mL for carboxylate and 0.30 ng/mL for lactone . Reproducible quantitation using a tunable fluorescence detector from 0.25 to 250 ng/mL for carboxylate and from 0.50 to 250 ng/mL for lact one was achieved, which is an improvement over existing methods. The f ilter detector, which has not been previously studied, provided reprod ucible detection from 0.50 to 250 ng/mL for carboxylate and from 0.75 to 250 ng/mL for lactone.