Fulvestrant

Many breast cancers have estrogen receptors (ER) and the growth of these tumors can be stimulated by estrogen. Fulvestrant is an estrogen receptor antagonist that binds to the estrogen receptor in a competitive manner with affinity comparable to that of estradiol and downregulates the ER protein in human breast cancer cells.

• Fulvestrant Injection is an estrogen receptor antagonist indicated for the treatment of: Hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative advanced breast cancer in postmenopausal women not previously treated with endocrine therapy. ( 1 ) HR-positive advanced breast cancer in postmenopausal women with disease progression following endocrine therapy.ICD-10: C50.919

• Fulvestrant Injection is contraindicated in patients with a known hypersensitivity to the drug or to any of its components. Hypersensitivity reactions, including urticaria and angioedema, have been reported in association with Fulvestrant Injection [see Adverse Reactions ( 6.2 )].contraindicated

Fulvestrant Injection 500 mg should be administered intramuscularly into the buttocks (gluteal area) slowly (1 - 2 minutes per injection) as two 5 mL injections, one in each buttock, on Days 1, 15, 29, and once monthly thereafter. ( 2.1 , 14 ) A dose of 250 mg is recommended in patients with moderate hepatic impairment to be administered intramuscularly into the buttock (gluteal area) slowly (1 - 2 minutes) as one 5 mL injection on Days 1, 15, 29, and once monthly thereafter. ( 2.2 , 5.2 , 8.6 ) 2.1 Recommended Dose Monotherapy The recommended dose of Fulvestrant Injection is 500 mg to be administered intramuscularly into the buttocks (gluteal area) slowly (1 - 2 minutes per injection) as two 5 mL injections, one in each buttock, on Days 1, 15, 29, and once monthly thereafter [see Clinical Studies ( 14 )]. Combination Therapy When Fulvestrant Injection is used in combination with palbociclib, abemaciclib, or ribociclib, the recommended dose of Fulvestrant Injection is 500 mg to be administered intramuscularly into the buttocks (gluteal area) slowly (1 - 2 minutes per injection) as two 5 mL injections, one in each buttock, on Days 1, 15, 29, and once monthly thereafter. When Fulvestrant Injection is used in combination with palbociclib, the recommended dose of palbociclib is a 125 mg capsule taken orally once daily for 21 consecutive days followed by 7 days off treatment to comprise a complete cycle of 28 days. Palbociclib should be taken with food. Refer to the Full Prescribing Information for palbociclib.

Risk of Bleeding: Use with caution in patients with bleeding diatheses, thrombocytopenia, or anticoagulant use. ( 5.1 ) Increased Exposure in Patients with Hepatic Impairment: Use a 250 mg dose for patients with moderate hepatic impairment. ( 2.2 , 5.2 , 8.6 ) Injection Site Reaction: Use caution while administering Fulvestrant Injection at the dorsogluteal injection site due to the proximity of the underlying sciatic nerve. ( 5.3 ) Embryo-Fetal Toxicity: Can cause fetal harm. Advise females of reproductive potential of the potential risk to a fetus and to use effective contraception. ( 5.4 , 8.1 , 8.3 ) Immunoassay Measurement of Serum Estradiol: Fulvestrant Injection can interfere with estradiol measurement by immunoassay, resulting in falsely elevated estradiol levels. ( 5.5 ) 5.1 Risk of Bleeding Because Fulvestrant Injection is administered intramuscularly, it should be used with caution in patients with bleeding diatheses, thrombocytopenia, or anticoagulant use. 5.2 Increased Exposure in Patients with Hepatic Impairment The safety and pharmacokinetics of Fulvestrant Injection were evaluated in a study in seven subjects with moderate hepatic impairment (Child-Pugh class B) and seven subjects with normal hepatic function. Exposure was increased in patients with moderate hepatic impairment, therefore a dose of 250 mg is recommended [see Dosage and Administration ( 2.2 )]. Fulvestrant Injection has not been studied in patients with severe hepatic impairment (Child-Pugh class C) [see Use in Specific Populations ( 8.6 )].

The following adverse reactions are discussed in more detail in other sections of the labeling: Risk of Bleeding [see Warnings and Precautions ( 5.1 )] Increased Exposure in Patients with Hepatic Impairment [see Warnings and Precautions ( 5.2 )] Injection Site Reaction [see Warnings and Precautions ( 5.3 )] Embryo-Fetal Toxicity [see Warnings and Precautions ( 5.4 )] The most common adverse reactions occurring in ≥5% of patients receiving Fulvestrant Injection 500 mg were: injection site pain, nausea, bone pain, arthralgia, headache, back pain, fatigue, pain in extremity, hot flash, vomiting, anorexia, asthenia, musculoskeletal pain, cough, dyspnea, and constipation. ( 6.1 ) Increased hepatic enzymes (ALT, AST, ALP) occurred in >15% of Fulvestrant Injection patients and were not dose-dependent. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Meitheal Pharmaceuticals, Inc. at 1-844-824-8426 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch . 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, the adverse reaction rates observed cannot be directly compared to rates in other trials and may not reflect the rates observed in clinical practice. Monotherapy Comparison of Fulvestrant Injection 500 mg and Fulvestrant Injection 250 mg (CONFIRM) The following adverse reactions (ARs) were calculated based on the safety analysis of CONFIRM comparing the administration of Fulvestrant Injection 500 mg intramuscularly once a month with Fulvestrant Injection 250 mg intramuscularly once a month.

Lactation: Advise not to breastfeed. ( 8.2 ) 8.1 Pregnancy Risk Summary Based on findings from animal studies and its mechanism of action, Fulvestrant Injection can cause fetal harm when administered to a pregnant woman [see Clinical Pharmacology ( 12.1 )]. There are no available data in pregnant women to inform the drug-associated risk. In animal reproduction studies, administration of fulvestrant to pregnant rats and rabbits during organogenesis caused embryo-fetal toxicity, including skeletal malformations and fetal loss, at daily doses that were 6% and 30% of the maximum recommended human dose based on mg/m 2 , respectively [see Data ] . Advise pregnant women of the potential risk to a fetus. The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2-4% and 15-20%, respectively. Data Animal Data Administration of fulvestrant to rats prior to and up to implantation caused embryonic loss at daily doses that were 0.6% of the daily maximum recommended human dose based on mg/m 2 .

Metabolism

Absorption The single dose and multiple dose PK parameters for the 500 mg dosing regimen with an additional dose (AD) at Day 15 are reported in Table 11 . The additional dose of Fulvestrant Injection given two weeks after the initial dose allows for steady state concentrations to be reached within the first month of dosing.

Human experience of overdose with Fulvestrant Injection is limited. There are isolated reports of overdose with Fulvestrant Injection in humans. No adverse reactions were seen in healthy male and female volunteers who received intravenous fulvestrant, which resulted in peak plasma concentrations at the end of the infusion, that were approximately 10 to 15 times those seen after intramuscular injection. The potential toxicity of fulvestrant at these or higher concentrations in cancer patients who may have additional comorbidities is unknown. There is no specific treatment in the event of fulvestrant overdose, and symptoms of overdose are not established. In the event of an overdose, healthcare practitioners should follow general supportive measures and should treat symptomatically.

• Apr 25, 2002NDANDA021344Astrazeneca
• Mar 4, 2019ANDAANDA210044Amneal
• May 14, 2019ANDAANDA205935Sandoz
• May 20, 2019NDANDA210326Fresenius Kabi Usa
• Aug 22, 2019ANDAANDA207754Glenmark Pharms
• Nov 21, 2019ANDAANDA209714Hbt Labs Inc
• Feb 7, 2020ANDAANDA211422Chia Tai Tianqing
• Aug 7, 2020ANDAANDA209246Dr Reddys

1. 1Malignant Neoplasm Progression4,11313%
2. 2Fatigue4,10213%
3. 3Nausea2,9479.2%
4. 4Death2,7078.4%
5. 5Diarrhoea2,5427.9%
6. 6Neutropenia2,4377.6%
7. 7White Blood Cell Count Decreased2,1596.7%
8. 8Neoplasm Progression2,1286.6%
9. 9Metastases To Bone2,0896.5%
10. 10Asthenia1,7305.4%
11. 11Pain1,7085.3%
12. 12Metastases To Liver1,6885.2%
13. 13Breast Cancer Metastatic1,6045.0%
14. 14Dyspnoea1,5965.0%
15. 15Vomiting1,5324.8%

Recent PubMed references pinned to Fulvestrant as a MeSH major topic. Citations link to pubmed.ncbi.nlm.nih.gov.

• Fulvestrant versus capecitabine as maintenance therapy in hormone receptor-positive, HER2-negative metastatic breast cancer after first-line chemotherapy (FAMILY): a multicenter, open-label, randomized, phase 3 trial.
  Signal transduction and targeted therapy · 2026 · Wu W, Yang Y, Chen H, et al.
  PMID 42168151DOI 10.1038/s41392-026-02720-6
• SGLT2 Inhibitor Dapagliflozin Attenuates Cardiomyocyte Injury and Inflammation Induced by PI3Kα-Selective Inhibitor Alpelisib and Fulvestrant Under Hyperglycemia.
  International journal of molecular sciences · 2026 · Quagliariello V, Berretta M, Barbato M, et al.
  PMID 42074235DOI 10.3390/ijms27083597
• Cost-effectiveness analysis of capivasertib plus fulvestrant in the PIK3CA/AKT1/PTEN-altered subgroup with HR+/HER2- advanced breast cancer: a United States payer perspective.
  Journal of medical economics · 2026 · Liang X, Malone DC, Tan CJ, et al.
  PMID 42009253DOI 10.1080/13696998.2026.2656072
• Alpelisib and Fulvestrant in PIK3CA-mutated hormone receptor-positive HER2-negative advanced breast cancer included in the German PRAEGNANT trial.
  Breast cancer research and treatment · 2026 · Hörner M, Tretschock LM, John N, et al.
  PMID 41925922DOI 10.1007/s10549-026-07939-z
• Abemaciclib plus fulvestrant in treating hormone-receptor positive, HER2-negative advanced breast cancer-comparing real-world outcomes in England to the MONARCH-2 trial.
  British journal of cancer · 2026 · Anderson J, Lawton S, Thackray K, et al.
  PMID 41912678DOI 10.1038/s41416-026-03396-z
• Bireociclib Plus Fulvestrant in Advanced Breast Cancer After Endocrine Progression: The BRIGHT-2 Phase 3 Randomized Clinical Trial.
  JAMA oncology · 2026 · Wang J, Zhang Q, Li H, et al.
  PMID 41854603DOI 10.1001/jamaoncol.2026.0318
• The impact of fulvestrant on estrogen receptor-driven chromatin dynamics in breast cancer cells.
  Epigenetics & chromatin · 2026 · Barlier C, Simplicien M, Hermoso A, et al.
  PMID 41840649DOI 10.1186/s13072-026-00667-0
• Imlunestrant plus abemaciclib versus fulvestrant plus abemaciclib in ER-positive, HER2-negative advanced breast cancer: an indirect treatment comparison of three phase III trials.
  ESMO open · 2026 · Jhaveri K, Bidard FC, Kalinsky K, et al.
  PMID 41785668DOI 10.1016/j.esmoop.2026.106091

The 10 most recently updated of 590 ClinicalTrials.gov registrations naming Fulvestrant as an intervention. Registration is not evidence of efficacy or safety — reference crosswalk only.

• Targeted Therapy Directed by Genetic Testing in Treating Patients With Locally Advanced or Advanced Solid Tumors, The ComboMATCH Screening Trial
  Recruiting · Phase 2 · Interventional · 2,900 enrolled · National Cancer Institute (NCI)
  NCT05564377updated 2026-06-12
• Nab-Sirolimus and Endocrine Therapy in Recurrent Low Grade Serous Ovarian Cancer (NARETO)
  Active not recruiting · Phase 2 · Interventional · 37 enrolled · University of Oklahoma
  NCT06494150updated 2026-06-12
• A Study to Evaluate the Effectiveness and Safety of Inavolisib in Participants With Endocrine-resistant, PIK3CA-mutated, Hormone Receptor-positive, HER2-negative Locally Advanced or Metastatic Breast Cancer
  Recruiting · Observational · 500 enrolled · Hoffmann-La Roche
  NCT07347600updated 2026-06-12
• A Trial of HRS-6209-205 to Evaluate the Safety, Tolerability, Pharmacokinetics and Efficacy of HRS-6209 in Combination Therapy in Subjects With HR-Positive/HER2-Negative Cancer
  Recruiting · Phase 1 · Interventional · 15 enrolled · Atridia Pty Ltd.
  NCT07358377updated 2026-06-12
• Phase 3 Study of RLY-2608 + Fulvestrant vs Capivasertib + Fulvestrant as Treatment for Locally Advanced or Metastatic PIK3CA-mutant HR+/HER2- Breast Cancer
  Recruiting · Phase 3 · Interventional · 540 enrolled · Relay Therapeutics, Inc.
  NCT06982521updated 2026-06-11
• Roll-over Study to Allow Continued Access to Ribociclib
  Active not recruiting · Phase 4 · Interventional · 134 enrolled · Novartis Pharmaceuticals
  NCT05161195updated 2026-06-11
• Study Assessing the Efficacy and Safety of Treatment With Alpelisib Plus Fulvestrant Versus Placebo Plus Fulvestrant in Chinese Men and Postmenopausal Women With Advanced Breast Cancer
  Active not recruiting · Phase 2 · Interventional · 69 enrolled · Novartis Pharmaceuticals
  NCT04544189updated 2026-06-11
• Study to Assess the Efficacy and Safety of Alpelisib Plus Fulvestrant in Participants With HR-positive (HR+), HER2-negative, Advanced Breast Cancer After Treatment With a CDK4/6 Inhibitor and an Aromatase Inhibitor.
  Active not recruiting · Phase 3 · Interventional · 210 enrolled · Novartis Pharmaceuticals
  NCT05038735updated 2026-06-11
• Study Assessing the Efficacy and Safety of Treatment With Alpelisib Plus Fulvestrant in Japanese Men and Postmenopausal Women With Advanced Breast Cancer
  Active not recruiting · Phase 2 · Interventional · 24 enrolled · Novartis Pharmaceuticals
  NCT04524000updated 2026-06-11
• Reversing InGuinal Hernia Trial: The Evaluation of Sex Hormones to Reverse Inguinal Hernias in Males
  Not yet recruiting · Phase 1 · Interventional · 30 enrolled · Northwestern University
  NCT07604272updated 2026-06-11

Frequently asked questions

How does Fulvestrant work?

Many breast cancers have estrogen receptors (ER) and the growth of these tumors can be stimulated by estrogen. Fulvestrant is an estrogen receptor antagonist that binds to the estrogen receptor in a competitive manner with affinity comparable to that of estradiol and downregulates the ER protein in human breast cancer cells.

What is Fulvestrant used for?

According to FDA labeling, Fulvestrant carries indications including: Fulvestrant Injection is an estrogen receptor antagonist indicated for the treatment of: Hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative advanced breast cancer in postmenopausal women not previously treated with endocrine therapy. ( 1 ) HR-positive advanced breast cancer in postmenopausal women with disease progression following endocrine therapy.. This is a reference summary of labeled uses, not medical advice or a treatment recommendation.

What class of drug is Fulvestrant?

Fulvestrant is classified as Anti-estrogens, Estrogen Receptor Antagonist, Estrogen Receptor Antagonists, Selective Estrogen Receptor Modulators, Decreased Ovarian Estrogen Secretion.

What are the brand names for Fulvestrant?

Fulvestrant is marketed under brand names including Faslodex.

What are the contraindications for Fulvestrant?

Fulvestrant labeling lists contraindications including: Fulvestrant Injection is contraindicated in patients with a known hypersensitivity to the drug or to any of its components. Hypersensitivity reactions, including urticaria and angioedema, have been reported in association with Fulvestrant Injection [see Adverse Reactions ( 6.2 )].. Always consult the full prescribing information and a clinician.