[Pharmacology and metabolism of a new therapeutic drug for prostatic cancer "Estracyt"].

Estracyt is a new drug for treatment of prostatic cancer, which is a molecule combining estradiol and nornitrogen mustard by a carbamate link. Estracyt is completely dephosphorylated prior to reaching the peripheral circulation after oral administration of the drug to men. Estramustine, i. e. dephosphorylated Estracyt, appears to be metabolized in liver as follows: Estramustine leads to estromustine leads to nitrogen mustard + estrone. There is a large amount of estramustine binding protein (EMBP) in the cytosol 3.5 S fraction of human prostatic cancer tissue, which is involved with the selective uptake and long term retention of both estramustine and estromustine in prostate. The anticancer action of Estracyt appears to be the sum of the direct prostatic action of estramustine and estromustine and the indirect prostatic action of free estradiol-17 beta and estrone via the inhibition of hypothalamo-pituitary axis. Estracyt Research Group in Japan concluded that Estracyt was effective in 38% of reactivated prostatic cancer patients (15% (I-C, I-B), 23% (I-A, O-B, O-C]. Side effects of this drug at the time of 3 months treatment is as follows: gastrointestinal disturbance in 36%, edema in 15%, and hepatic disorder in 7%.