Irinotecan (CPT-11) metabolites in human bile and urine.
A female patient was treated with irinotecan (CPT-11) for liver metastatic colon carcinoma. She had a percutaneous biliary catheter because of extrahepatic biliary obstruction. The patient was treated with CPT-11 for three courses at doses of 350 mg/m2 for the first course and 300 mg/m2 for the remaining courses, given as a 30-min i. v. infusion. Metabolism studies in bile and urine were performed by coupling high-performance liquid chromatography to electrospray mass spectrometry. Conventional spectra [liquid chromatography/mass spectrometry (LC/MS)] allowed on-line molecular mass determination of CPT-11 and its main metabolites, whereas structural information was obtained by tandem mass spectrometry (LC/MS/MS). At least 16 metabolites were detected in bile, while 8 of them were also detected in urine. Three compounds were identified as the parent drug, the active metabolite 7-ethyl-10-hydroxycamptothecin (SN-38), and SN-38 glucuronide. The major metabolic pathway consists in oxidations of the terminal piperidine ring of the CPT-11 side chain, which eventually results in the formation of a primary amine. Other metabolites result from oxidation of the camptothecin nucleus. Finally, decarboxylation of the carboxylate form of CPT-11 was also observed. Several metabolites result from combinations of these pathways. The structures of the identified metabolites indicate for the first time a major role of monooxygenases in the elimination of a camptothecin derivative in humans. This finding will allow better understanding of interindividual variability in pharmacokinetics and intestinal toxicity of CPT-11.
Lokiec
F
F
Department of Pharmacology, Centre René Huguenin, 35 rue Dailly, F-92210 Saint-Cloud, France.
du Sorbier
B M
BM
Sanderink
G J
GJ
D000972:Antineoplastic Agents, Phytogenic / Q000378:metabolism* / Q000627:therapeutic use / Q000652:urine; D001646:Bile / Q000378:metabolism*; D002166:Camptothecin / Q000031:analogs & derivatives* / Q000378:metabolism / Q000627:therapeutic use / Q000652:urine; D003110:Colonic Neoplasms / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D005260:Female; D006801:Humans; D000077146:Irinotecan; D008113:Liver Neoplasms / Q000188:drug therapy / Q000378:metabolism* / Q000556:secondary; D013058:Mass Spectrometry; D008875:Middle Aged; D009362:Neoplasm Metastasis
D000972:Antineoplastic Agents, Phytogenic; D000077146:Irinotecan; D002166:Camptothecin