PERMEABILITY OF N,N-BIS(2-CHLOROETHYL)-DIAMIDO-PHOSPHORIC-ACID INTO TUMOR-CELLS

The uptake of tritiated N,N-bis(2-chloroethyl)-diamido-phosphoric-acid into Ehrlich-Ascites-Tumor Cells of mice was studied by means of the siliconoil-filtration technique. At 10 m M concentration no permeation of the metabolite into the tumor cells could be found within 5 min at 1°C, while its congenors cyclophosphamide and 4-hydroperoxycyclophosphamide (1 m M) were shown to permeate into the cells very easily reaching saturation values. Thus lack of permeation into tumor cells of N,N-bis(2-chloroethyl)-diamidophosphoric-acid seems to be the reason for the poor cytotoxic activity of this metabolite of cyclophosphamide. © 1979 Springer-Verlag.