W34 is a prodrug of FL118, and it can be converted to FL118 via a hydrolysis reaction. In this report, a highly sensitive LC-MS/MS method using a C18 column was validated and used for the simultaneous determination of W34 and FL118 in rat blood. A stepwise gradient elution with 0.1% formic acid in water and acetonitrile was employed. The assays were linear over a concentration range of 0.50-50.0 ng/ml for both W34 and FL118. The accuracy of the validation method ranged from 89.74 to 98.94% for W34 and from 88.61 to 94.60% for FL118. The precision was within 7.15% for W34 and 9.63% for FL118. Extraction recoveries of W34 were 94.56-100.49 and 87.67-106.32% for FL118. No significant matrix effects for both W34 and FL118 were observed in blood. The assay has been successfully applied to biological samples obtained from a stability and pharmacokinetic study of W34 and FL118.
Keywords: FL118; LC-MS/MS; W34; camptothecin; pharmacokinetics.
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