Begg A C, Smith K A
Br J Cancer. 1984 Jan;49(1):49-55. doi: 10.1038/bjc.1984.8.
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.
已开发出一种生物测定法，用于检测和定量小鼠血液、肿瘤及肺中细胞毒性环磷酰胺（CY）代谢物的浓度。从给予CY的小鼠身上采集血液或实体组织并制成提取物，然后用这些提取物在培养中处理对数期中国仓鼠V79细胞长达24小时。7天后通过集落形成来检测细胞杀伤量。研究了孵育时间、CY剂量以及CY注射后组织采样时间的影响。该生物测定法能够检测腹腔注射低至10 mg/kg CY剂量后血液中的细胞毒性代谢物。腹腔注射400 mg/kg后，这些代谢物在血液中的半衰期在2小时内从14分钟降至9分钟。然后对该方法进行了改进，以确定CY代谢物在两种不同类型肿瘤及肺中的药代动力学。肺中细胞毒性代谢物的半衰期比血液中长，在2小时内从35分钟降至11分钟。在肿瘤中，半衰期更长，约为61分钟。尽管两种肿瘤类型对CY的治疗反应明显不同，但达到的最大代谢物水平相似。CY生物测定法是一种相对简单且快速的程序，将其应用从体液扩展到实体组织使其成为实验药代动力学研究中的一种有用工具。
