Different uptake of two alkylating substances by ascites tumor cells

Considerable quantitative differences have been observed between alkylating agents with respect to their effect on cell multiplication of tumor cells. The ethyleneimine derivative triaziquone is approximately a thousand times more effective than the biologically active conversion products of the nitrogen mustard derivative cyclophosphamide. The main difference may be directly related to the extent to which each of the two substances is able to pass into the cells. After a 60-min incubation period approximately 1% of the cyclophosphamide conversion products have been bound by ascites tumor cells. The uptake of the more lipophilic triaziquone, however, is nearly 50% under identical conditions.