Nature of estrogenic and anti-estrogenic actions of centchroman on rat uterus.

The uterine effects of centchroman, 3,4-trans-2,2-dimethyl-3-phenyl- 4-(p(beta-pyrrolidioethoxy)-phenyl)-7-methoxy chroman hydrochloride in ovariectomized rats, with or without estrogen treatment, were studied. Centchroman had a very weak estrogenic action in the absence of exogenous estrogen. However, it did have a relatively strong antiestrogenic action when estradiol benzoate was administered. The results indicate a competitive inhibition of estrogen action at the receptor site. It is suggested that the action of centchroman is similar to that of clomiphene.