Indications
Fulvestrant is an estrogen receptor antagonist. It is used to treat hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative advanced breast cancer in postmenopausal women who have not had endocrine therapy before. It is also used for HR-positive advanced breast cancer in postmenopausal women whose disease has progressed after endocrine therapy. Faslodex is an estrogen receptor antagonist too, and it is indicated for the same two uses: HR-positive, HER2-negative advanced breast cancer in postmenopausal women not previously treated with endocrine therapy, and HR-positive advanced breast cancer in postmenopausal women with disease progression following endocrine therapy. It is also indicated for HR-positive, HER2-negative advanced or metastatic breast cancer in postmenopausal women when given in combination with ribociclib, either as the first endocrine based therapy or after disease progression on endocrine therapy. And it is indicated for HR-positive, HER2-negative advanced or metastatic breast cancer in women whose disease has progressed after endocrine therapy, when given in combination with palbociclib or abemaciclib.
⚠️ Always consult a registered physician before taking any medicine.
Pharmacology
Many breast cancers have estrogen receptors (ER), and estrogen can stimulate the growth of these tumors. Fulvestrant is an estrogen receptor antagonist. It binds to the estrogen receptor in a competitive way, with an affinity comparable to that of estradiol, and it downregulates the ER protein in human breast cancer cells.
In vitro studies showed that fulvestrant is a reversible inhibitor of the growth of tamoxifen-resistant human breast cancer (MCF-7) cell lines, as well as estrogen-sensitive ones. In in vivo tumor studies, fulvestrant delayed the establishment of tumors from xenografts of human breast cancer MCF-7 cells in nude mice. It also inhibited the growth of established MCF-7 xenografts and of tamoxifen-resistant breast tumor xenografts.
Fulvestrant showed no agonist-type effects in in vivo uterotrophic assays in immature or ovariectomized mice and rats. In in vivo studies in immature rats and ovariectomized monkeys, it blocked the uterotrophic action of estradiol. In postmenopausal women, plasma concentrations of FSH and LH did not change in response to fulvestrant treatment (250 mg monthly), which suggests no peripheral steroidal effects.
Pregnancy & Breastfeeding
We don't have any data from pregnant women, so the risk of fulvestrant in pregnancy isn't known. Nor is it known whether fulvestrant passes into human milk, or what effect it might have on milk production or on a breastfed infant.
⚠️ Talk to your doctor before taking any medicine during pregnancy or while breastfeeding.
Dosage Reference
⚠️ Reference ranges from official sources only. Consult your doctor for personalized dosing.
Side Effects & Interactions
Side Effects
No side-effect data recorded yet.