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Stabilities of 3 H‐ and 2 H‐labelled camptothecins
Author(s) -
Hinz Hellmuth R.,
Harris Nicholas J.,
Giovanella Beppino C.,
Ezell Edward L.,
Liehr Joachim G.
Publication year - 1996
Publication title -
journal of labelled compounds and radiopharmaceuticals
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.432
H-Index - 47
eISSN - 1099-1344
pISSN - 0362-4803
DOI - 10.1002/(sici)1099-1344(199608)38:8<733::aid-jlcr888>3.0.co;2-6
Subject(s) - camptothecin , chemistry , tritium , deuterium , in vivo , radiochemistry , chromatography , incubation , nuclear chemistry , organic chemistry , biochemistry , physics , microbiology and biotechnology , quantum mechanics , nuclear physics , biology
Commercially available [ 3 H]‐camptothecin, labeled mainly at the C‐5 position, had partially lost the tritium label after recovery from the plasma of a patient injected with this drug or after incubation in plasma at 38°C for 72 h. Camptothecin dissolved in CH 3 O 2 H/ 2 H 2 O, incorporated deuterium at the C‐5 position with a 50% uptake after one day at pH 11.0 or after 10–11 days at pH 7.4. At pH 2.0, the deuterium uptake was negligible. Camptothecin, dissolved in deuterated sulfuric acid, incorporated 37 or 80% deuterium at C‐14 when heated to 65 or 80°C, respectively. Commercially available [ 3 H]‐camptothecin, labeled mainly at the C‐5 position, is thus not useful for in vivo metabolism or pharmacokinetic studies due to rapid loss of tritium in plasma. In contrast, [ 3 H]‐camptothecin prepared as described in this paper for [ 2 H]‐camptothecin is expected to be useful.