ER antagonists mechanism & types

Estrogen receptor antagonists: FULVESTRANT, RALOXIFENE, TAMOXIFEN, TOREMIFENE

Selective ER modulators (SERMs): may function as estrogen-receptor agonists, antagonists, or mixed agonist-antagonists, depending on the target tissue

Selective ER downregulators (SERDs): competitive antagonists in every tissue
- FULVESTRANT

	Breast	Uterus	Bone
Estrogen	Proliferative	Proliferative	Anti-resorptive
TAMOXIFEN SERM	Antagonist (partial agonist)	Agonist	Agonist (postmenopausal women only)
TOREMIFENE SERM	Antagonist	Probably agonist	No effect
RALOXIFENE SERM	Antagonist	Antagonist	Agonist
FULVESTRANT SERD	Antagonist	Antagonist	Antagonist