Sensitive high-performance liquid chromatographic fluorescence assay for the quantitation of topotecan (SKF 104864-A) and its lactone ring-opened product (hydroxy acid) in human plasma and urine.
A sensitive reversed-phase high-performance liquid chromatographic fluorescence method is described for the simultaneous determination of topotecan (I) and the hydrolysed lactone ring-opened product hydroxy acid (II) in plasma and for the determination of I in urine. To 250 microliters of plasma, a 750-microliters volume of cold methanol was added to stabilize the pH-dependent conversion of I into II. In plasma, the lower limit of quantitation (LLQ) for both compounds was 0.10 ng/ml. The between-day variation for I at the LLQ was 7.1% and for II was 5.5%. Prior to injection, urine samples were acidified with orthophosphoric acid and diluted with phosphate-buffered saline (PBS). In urine, the calibration curve for I was linear in the range of 10 to 250 ng/ml and the LLQ was 10 ng/ml. The assay was developed to enable pharmacological analysis of I, in on-going phase I and II studies, in patients with solid tumors.
Loos
W J
WJ
Department of Medical Oncology, Rotterdam Cancer Institute/University Hospital Rotterdam, Netherlands.
Stoter
G
G
Verweij
J
J
Schellens
J H
JH
D002166:Camptothecin / Q000031:analogs & derivatives* / Q000097:blood / Q000652:urine; D002851:Chromatography, High Pressure Liquid / Q000379:methods* / Q000706:statistics & numerical data; D004355:Drug Stability; D004791:Enzyme Inhibitors / Q000097:blood* / Q000652:urine*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D006880:Hydroxy Acids / Q000097:blood / Q000652:urine; D007700:Kinetics; D012044:Regression Analysis; D012680:Sensitivity and Specificity; D059004:Topoisomerase I Inhibitors; D019772:Topotecan
D004791:Enzyme Inhibitors; D006880:Hydroxy Acids; D059004:Topoisomerase I Inhibitors; D019772:Topotecan; D002166:Camptothecin