Contribution to the mechanism of Stilbostat action.

The hormone-cytostatic drug Stilbostat does not influence the estradiol binding capacity of the rat uterus tissue and tissues of human and experimentally induced mammary tumors. It exhibits an alkylating potency similar to that of other cytostatic drugs used in the therapy of neoplasia. An in vitro splitting of Stillbostat into diethylstilbestrol by tissue slices could not be detected. It was impossible to demonstrate an excretion of splitting products of Stilbostat by rat urine.