Diethylstilbestrol di-trimethylacetate (DSTMA). A long-acting estrogen

A series of estradiol and diethylstilbestrol (DES) esters was prepared as part of a study of the structure-activity relations in estrogens. Among the esters tested, DES di-trimethylacetate (DSTMA) exhibited the most favorable combination of a low minimum-effective dose and prolongation of effect in all experimental groups (mice, rats, dogs). Toxicity of DSTMA was low. A clinical trial in four stage III and stage IV prostatic cancer patients showed that dosage levels of DSTMA as high as 75 mg per day for short periods were well tolerated and no toxic symptoms attributable to the estrogen itself were observed.