Abstract
A bioassay has been developed to detect and quantify the concentration of cytotoxic metabolites of cyclophosphamide (CY) in blood, tumour, and lungs of mice. Extracts were made of blood or solid tissues taken from mice given CY and these were used to treat log phase Chinese Hamster V79 cells in culture for up to 24 h. The amount of cell killing was tested by colony formation 7 days later. The effects of incubation time, CY dose, and the time of tissue sampling after CY injection were investigated. The bioassay could detect cytotoxic metabolites in blood after doses as low as 10 mg kg-1 CY given i.p. The half life of these metabolites in blood after giving 400 mg kg-1 i.p. decreased over a 2 h period from 14 to 9 min. The method was then modified to define the pharmacokinetics of CY metabolites in two different types of tumour and in lung. The half life of the cytotoxic metabolites in the lung was longer than in blood, falling from 35 to 11 min over a 2 h period. In tumours, the half lives were longer again, i.e. approximately 61 min. The maximum metabolite levels achieved were similar in the two tumour types, although these differed markedly in their therapeutic response to CY. The bioassay for CY is a relatively simple and rapid procedure, and the extension of its application from body fluids to solid tissues makes it a useful tool in experimental pharmacokinetic studies.
Full text
PDF
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Brock N. Comparative pharmacologic study in vitro and in vivo with cyclophosphamide (NSC-26271), cyclophosphamide metabolites, and plain nitrogen mustard compounds. Cancer Treat Rep. 1976 Apr;60(4):301–308. [PubMed] [Google Scholar]
- Brock N., Hohorst H. J. Metabolism of cyclophosphamide. Cancer. 1967 May;20(5):900–904. doi: 10.1002/1097-0142(1967)20:5<900::aid-cncr2820200552>3.0.co;2-y. [DOI] [PubMed] [Google Scholar]
- Connors T. A., Grover P. L., McLoughlin A. M. Microsomal activation of cyclophosphamide in vivo. Biochem Pharmacol. 1970 Apr;19(4):1533–1535. doi: 10.1016/0006-2952(70)90077-8. [DOI] [PubMed] [Google Scholar]
- Cox P. J., Phillips B. J., Thomas P. The enzymatic basis of the selective action of cyclophosphamide. Cancer Res. 1975 Dec;35(12):3755–3761. [PubMed] [Google Scholar]
- Domeyer B. E., Sladek N. E. Kinetics of cyclophosphamide biotransformation in vivo. Cancer Res. 1980 Jan;40(1):174–180. [PubMed] [Google Scholar]
- Fenselau C., Kan M. N., Rao S. S., Myles A., Friedman O. M., Colvin M. Identification of aldophosphamide as a metabolite of cyclophosphamide in vitro and in vivo in humans. Cancer Res. 1977 Aug;37(8 Pt 1):2538–2543. [PubMed] [Google Scholar]
- Fu K. K., Begg A. B., Kane L. J., Phillips T. L. Interaction of radiation and adriamycin on the EMT6 tumor as a function of tumor size and assay method. Int J Radiat Oncol Biol Phys. 1979 Aug;5(8):1249–1254. doi: 10.1016/0360-3016(79)90648-5. [DOI] [PubMed] [Google Scholar]
- Sladek N. E. Bioassay and relative cytotoxic potency of cyclophosphamide metabolites generated in vitro and in vivo. Cancer Res. 1973 Jun;33(6):1150–1158. [PubMed] [Google Scholar]
- Sladek N. E. Metabolism of cyclophosphamide by rat hepatic microsomes. Cancer Res. 1971 Jun;31(6):901–908. [PubMed] [Google Scholar]
- Steel G. G., Adams K. Stem-cell survival and tumor control in the Lewis lung carcinoma. Cancer Res. 1975 Jun;35(6):1530–1535. [PubMed] [Google Scholar]
- Tannock I. F. In vivo interaction of anti-cancer drugs with misonidazole or metronidazole: cyclophosphamide and BCNU. Br J Cancer. 1980 Dec;42(6):871–880. doi: 10.1038/bjc.1980.335. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Twentyman P. R., Bleehen N. M. The sensitivity to cytotoxic agents of the EMT6 tumor in vivo. Comparative response of lung nodules in rapid expotential growth and of the solid flank tumour. Br J Cancer. 1976 Mar;33(3):320–328. doi: 10.1038/bjc.1976.46. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Weaver F. A., Torkelson A. R., Zygmunt W. A., Browder H. P. Tissue culture cytotoxicity assay for cyclophosphamide metabolites in rat body fluids. J Pharm Sci. 1978 Jul;67(7):1009–1012. doi: 10.1002/jps.2600670738. [DOI] [PubMed] [Google Scholar]