Effect of Different Lactone Percentage of 9-nitrocamptothecin to Biliary Excretion

OBJECTIVE To investigate the effect of administered 9-nitrocamptothecin(9-NC) forms (lactone or carboxylate form) on biliary excretion. METHODS The accurate HPLC method was developed for quantifying 9-NC in bile samples of rats. Then the ratios of cumulative excretion in bile were determined at different time following intravenous administration of 4 mg?kg^-1 9-NC solution with different lactone percentages to rats. RESULTS Following injection of 9-NC solution of 100%, 75%, 50%, 25% and 0% lactone ratios, the ratios of cumulative excretion in bile to the dose were determined to be (7.03±2.23)%, (13.36±0.83)%, (22.68±4.83)%, (28.01±6.71)%, (32.65±2.82)%, respectively. CONCULSION 9-NC in carboxylate form is easily excreted in bile compared to lactone form.