Metabolism of the antineoplastic and immunosuppressive drug 2-CdA (Leustatin) in animals and humans.
1. The in vivo metabolism of the antineoplastic and immunosuppressive drug 2-CdA (Leustatin) was investigated in mice, monkeys and humans after a single subcutaneous dose of cladribine 60 mg kg(-1) to eight male and eight female mice and 10 mg kg(-1) to one male and one female monkey, and an intravenous infusion dose of cladribine 22-45 mg(-1) per subject to 12 male patients. 2. Plasma (1 h), red blood cells (1 h) and faecal samples (0-24 h) were obtained from mice and monkeys, and urine samples (0-24 h) were obtained from these species and humans. 3. Unchanged cladribine (urine: 47% of the sample in human; 60% of the sample in mouse; 73% of the sample in monkey) and 10 metabolites, consisting of four phase I metabolites (M1-3, M7) and six phase II metabolites -- five glucuronides (M4, M6, M8-10) and one sulfate (M5) -- were profiled, characterized and tentatively identified in plasma, red blood cells, and faecal and urine samples on the basis of API ionspray-mass spectrometry (MS) and MS/MS data. 4. Metabolites were formed via the following three metabolic pathways: oxidative cleavage at the adenosine and deoxyribose linkage (A); oxidation at adenosine/deoxyribose (B); and conjugation (C). 5. Pathways A and B appear to be major steps, forming four oxidative/cleavage metabolites (M1-3, M7) (each 3-20% of the sample). 6. Pathway C along or in conjunction with pathways A and B produced cladribine glucuronide, cladribine sulfate and four glucuronides of oxidative/cleavage metabolites in minor/trace quantities (each < or = 5% of the sample). 7. In addition, the in vitro metabolism of cladribine was conducted using rat and human liver microsomal fractions in the presence of an beta-nicotinamide adenine dinucleotide phosphate-generating system. Unchanged cladribine (> or = 90% of the sample) plus three minor metabolites, M1-3 (each < 8% of the sample), were profiled and tentatively identified by thin-layer chromatography and MS data. 8. Cladribine is not extensively metabolized in vitro and in vivo in all species. However, humans appear to metabolize cladribine to a greater extent than other animals.
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Division of Preclinical Drug Evaluation, Johnson & Johnson Pharmaceutical Research & Development, L.L.C, Spring House, PA, USA.
McKown
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Moyer
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Cheung
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D000818:Animals; D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000378:metabolism* / Q000493:pharmacokinetics* / Q000652:urine; D017338:Cladribine / Q000008:administration & dosage / Q000378:metabolism* / Q000493:pharmacokinetics* / Q000652:urine; D005260:Female; D000882:Haplorhini; D006801:Humans; D007166:Immunosuppressive Agents / Q000008:administration & dosage / Q000378:metabolism* / Q000493:pharmacokinetics* / Q000652:urine; D008297:Male; D013058:Mass Spectrometry; D051379:Mice; D008862:Microsomes, Liver / Q000378:metabolism; D015394:Molecular Structure
D000970:Antineoplastic Agents; D007166:Immunosuppressive Agents; D017338:Cladribine