The purpose of this study was to evaluate the distribution of CPT-11 and its active metabolite, SN-38, in pleural and pericardial fluid after intravenous administration.
Two patients with lung cancer were treated with intravenous CPT-11 (60 mg/m2) on days 1, 8, and 15. The CPT-11 was detected in the pleural fluid 1.5 hr after the begining of intravenous infusion, and the level reached the maximum 24 hrs later. Similarly, the active metabolite SN-38 was detected in the pleural fluid 1.5 hr after the begining of intravenous infusion, and SN-38 concentration in the pleural fluid was almost as high as that in plasma 24 hrs later. These results suggest that intravenously administered CPT-11 may penetrate the thoracic cavity and may be metabolized to SN-38 there. The proportions of maximum concentrations of CPT-11 and SN-38 in the pleural fluid to the corresponding plasma levels were 20.4% and 28.5%, respectively. In addition, the AUCs of the lactone form SN-38 were much lower than those of the carboxyl form in the pleural fluid.
CPT-11, SN-38 and SN-38 glucronide showed similar pharmacokinetics in the pericardium as that in plasma.
