Tamoxifen
Mechanism of action
- Competitive antagonist on the estrogen receptors of the breast → ↓ breast cancer cell growth
- Agonist on estrogen receptors in the following tissues:
- Bone tissue → inhibition of osteoclasts → ↓ risk of osteoporosis and fractures
- Endometrium → ↑ proliferation
- Myometrium → ↑ proliferation
Indications
Side effects
Raloxifene
Mechanism of action
- Competitive antagonist on estrogen receptors in the following tissues:
- Breast → ↓ breast cancer cell growth
- Endometrium and myometrium → ↓ proliferation (in contrast to tamoxifen)
- Agonist on estrogen receptor in bone tissue → inhibition of osteoclasts
Indications
Side effects
Clomiphene
Mechanism of action
- Blocks hypothalamic estrogen receptors, thereby inhibiting negative feedback and increasing release of FSH and LH to trigger ovulation
Indications
- Infertility (for ovulation induction)
Side effects