Clomiphene citrate is an antiestrogen belonging to the triphenylethylene group. It is classified as selective estrogen receptor modulator with mixed agonist and antagonistic properties This means that in certain tissues they block the action of estrogen by binding to receptors, while there is an exception – the  bone tissue, where, on the contrary, it. activates estrogen receptors, and its useful feature to prevent osteoporosis.
In men, both drugs act as antiestrogens in their ability to interfere with the negative feedback of estrogens to the hypothalamus and stimulate increased production of GnRH (gonadoliberin), which increase the production of LH and FSH hormones by the pituitary gland, triggering the synthesis of testosterone and sperm in the testicles.

EFFECTS:
blocking estrogen receptor(mostly active in brain)
increase production of endogenous testosterone(as the part of PCT or anti-age therapy).
strengthens bones.
prevents the estrogen induced gynecomastia.
clomiphene  acts on estrogen receptors in the pituitary gland and ovaries. By binding the estrogen receptors in the pituitary gland, clomiphene breaks the negative feedback mechanism, i.e. if usually estrogens, acting on the pituitary gland, reduce the production of FSH and LH, then when taking clomiphene this does not happen. Clomiphene does not directly affect the level of estrogen in the blood.
thus, clomiphene acts as an antagonist of estrogens and eliminates their inhibitory effect on the hypothalamus and pituitary gland, contributing to a more rapid restoration of their function.