Abstract: AimTo develop a sensitive, specific and accurate method for quantifying 9-nitrocamptothecin in rat plasma and tissues and to study the distribution of 9-nitrocamptothecin in rat tissues. MethodsPlasma and tissue samples were prepared based on a simple liquid-liquid extraction and separation through a Hypersil BDS C₁₈ column. The mobile phase for plasma samples and tissue samples consisted of a mixture of acetonitrile-water-formic acid (35∶65∶2) and a mixture of acetonitrile-water-formic acid (30∶70∶2), respectively. The UV detector was set at 370 nm. ResultsA linear calibration curve of 9-nitrocamptothecin in plasma was obtained in the concentration range of 25-1 600 μg·L^-1, and the quantitation limit of plasma and tissues was 25 μg·L^-1. A linear range of concentrations for 9-nitrocamptothecin in heart, lung, spleen, stomach, fat, womb, and ovary was 10-1 000 ng·g^-1, and the quantitation limit was 10 ng·g^-1. A linear range of concentrations for 9-nitrocamptothecin in brain, kidney, liver, intestine, smooth muscle, skeletal muscle, and tectical was 5-500 ng·g^-1, and the quantitation limit was 5 ng·g^-1. The intra- and inter-run precision was measured to be below 11%. The inter-run accuracy was less than 5% for the analyte. After iv administration of 9-nitrocamptothecin, the drug was distributed extensively in rat in vivo. The concentration in lung was the highest, and the drug was accumulated in lung and liver. Following ig administration, the concentration in stomach was higher than that in other organs. ConclusionThe method is shown to be accurate and convenient, and suitable for preclinical pharmacokinetic studies of 9-nitrocamptothecin.