Stabilities of 3H- and 2H-labelled camptothecins

✍ Scribed by Hellmuth R. Hinz; Nicholas J. Harris; Beppino C. Giovanella; Edward L. Ezell; Joachim G. Liehr

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: French
• Weight: 386 KB
• Volume: 38
• Category: Article
• ISSN: 0022-2135
• DOI: 10.1002/(sici)1099-1344(199608)38:8<733::aid-jlcr888>3.0.co;2-6

✦ Synopsis

Commercially available [3Hl-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 38OC for 72 h. Carnptothecin dissolved in CH302H/2Hz0, incorporated deuterium at the C-5 position with a 50% uptake after one day at pH 11 .O or after 10-1 1 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 [3Hl-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, [3Hl-camptothecin prepared as described in this paper for ['HI-camptothecin is expected to be useful.