Diltiazem does not increase the in vivo sensitivity of murine hemopoietic progenitor cells to doxorubicin.

The effect of doxorubicin and the calcium antagonist, diltiazem, on murine hemopoietic progenitor cells was studied in vivo. Dose-survival curves of murine bone marrow colony forming units (CFU)--spleen and granulocyte macrophage--were determined by in vivo and in vitro methods in DBA/2NCr/BR mice treated with doxorubicin alone or by simultaneous administration of doxorubicin (DX) and diltiazem (DTZ). Time response of bone marrow hematopoietic progenitor cells (HPC) was followed in mice similarly treated. Combination of DTZ with DX did not change the toxic effect of the latter on hemopoietic cells, either in the dose-survival model or in the time-related experiment.