From the Guidelines
Fulvestrant is administered as an intramuscular injection, typically given as two separate injections (one in each buttock) of 250 mg each, for a total dose of 500 mg, with a loading dose followed by 500 mg every 28 days, as recommended by the most recent and highest quality study 1.
Administration Details
The standard dosing schedule begins with the first dose, followed by another dose two weeks later, then another dose four weeks later, and subsequently continues with monthly injections.
- These injections must be given slowly into the muscle by a healthcare professional, usually a nurse or doctor, in a clinical setting.
- The medication comes as a pre-filled syringe and should be stored in the refrigerator until shortly before use.
Mechanism of Action and Side Effects
Fulvestrant works as an estrogen receptor antagonist by binding to estrogen receptors in breast cancer cells and blocking estrogen's stimulatory effects, which helps slow or stop the growth of hormone-receptor-positive breast cancer.
- Patients may experience injection site pain, so the healthcare provider might recommend applying ice to reduce discomfort.
- Other common side effects include hot flashes, nausea, and bone pain, which patients should be aware of when receiving this treatment, as reported in studies such as 1 and 1.
Clinical Guidelines
The administration of fulvestrant is supported by clinical guidelines, including those from the American Society of Clinical Oncology 1, which recommend fulvestrant as a treatment option for hormone receptor-positive metastatic breast cancer.
- The guidelines emphasize the importance of sequential hormone therapy and the use of fulvestrant in combination with other endocrine agents, as studied in trials such as SWOG S0226 1.
From the FDA Drug Label
PACKAGE LABEL. PRINCIPAL DISPLAY PANEL NDC 70771-1626-2 Fulvestrant Injection 250 mg/5 mL (50 mg/mL) For Intramuscular Use Only Both single-dose prefilled syringes must be administered to receive the 500 mg dose This carton contains a total of 500 mg fulvestrant in TWO single-dose prefilled syringes each containing 250 mg/5 mL, and two Safety Glide™ shielding intramuscular injection needles. Both single-dose prefilled syringes must be administered to receive the 500 mg dose.
Fulvestrant is given intramuscularly. The recommended dose is administered using two single-dose prefilled syringes, each containing 250 mg/5 mL, to receive a total dose of 500 mg 2.
From the Research
Administration of Fulvestrant
- Fulvestrant is administered via intramuscular injections 3, 4, 5, 6, 7
- The recommended dose of fulvestrant is 500 mg, which is given monthly with a loading dose on day 15 of the first month and every 28 days thereafter 4, 5, 7
- A lower dose of 250 mg is also used, but studies have shown that the 500 mg dose has a better efficacy profile 4, 7
- Fulvestrant can be used as a second-line therapy for the treatment of hormone receptor-positive metastatic breast cancer in postmenopausal women who have progressed following prior endocrine therapy 3, 4, 6, 7
Key Points
- Fulvestrant is an estrogen receptor antagonist with no known agonist effects 3, 4, 6
- It is effective in the treatment of tamoxifen-resistant disease and has a distinct mechanism of action that ensures a lack of cross-resistance with other hormonal agents 3
- Fulvestrant is generally well-tolerated, with mostly mild to moderate treatment-related adverse events 3, 4, 5, 7