Pharmacodynamics<unk>  is an antiestrogen which acts as an antagonist of the estrogen receptor (ER) and additionally as a selective estrogen receptor degrader (SERD). It works by binding to the estrogen receptor and making it more hydrophobic, which makes the receptor unstable and misfold, which in turn leads normal processes inside the cell to degrade it. In addition to its antiestrogenic activity,<unk>  is an agonist of the G protein-coupled estrogen receptor (GPER), albeit with relatively low affinity (10–100 nM, relative to 3–6 nM for estradiol). Pharmacokinetics<unk>  after an intramuscular injection is slowly absorbed and maximal levels (Cmax) are reached after 5 days on average with a range of 2 to 19 days. The elimination half-life of<unk>  with intramuscular injection is 40 to 50 days. This is 40 times longer than the half-life of<unk>  by intravenous injection, indicating that its long half-life with intramuscular injection is due to slow absorption from the injection site. Levels of<unk>  with 500 mg/month by intramuscular injection (and a single additional 500 mg loading dose on day 15 of therapy) in postmenopausal women with advanced breast cancer were 25.1 ng/mL (25,100 pg/mL) at peak and 28.0 ng/mL (28,000 pg/mL) at trough with a single dose and 28.0 ng/mL (28,000 pg/mL) at peak and 12.2 ng/mL (12,200 pg/mL) at trough after multiple doses at steady state.<unk>  does not cross the blood–brain barrier in animals and may not in humans as well. Accordingly, no effects of<unk>  on brain function have been observed in preclinical or clinical research.<unk>  is highly (99%) bound to plasma proteins. It is bound to very low density lipoprotein, low density lipoprotein, and high density lipoprotein, but not to sex hormone-binding globulin.<unk>  appears to be metabolized along similar pathways as endogenous steroids; CYP3A4 may be involved, but non-cytochrome P450 routes appear to be more important. It does not inhibit any cytochrome P450 enzymes. Elimination is almost all via feces.<unk>  can form colloidal aggregates at certain concentration ranges and this can limit its activity as well as produce bell-shaped concentration–response curves.
Fulvestrant
Salvestrol
Tamoxifen
Anastrozole
N-Desmethyltamoxifen
Goserelin
Exemestane
Endoxifen