DrugindexOnline^{2nd edition}

Pronouncation: (fool-VESS-trant)
Class: Antiestrogen

Trade Names:
Faslodex
- Solution for injection 50 mg/mL

Mechanism of Action

Pharmacology

Fulvestrant competitively binds to the estrogen receptor and downregulates the estrogen receptor protein in human breast cancer cells.

Pharmacokinetics

Absorption

C _max is about 8.5 ng/mL and about 15.8 ng/mL at steady state. T _max is 7 days. C _min is about 2.6 ng/mL and about 7.4 ng/mL at steady state. AUC is about 131 ng•day/mL and about 328 ng•day/mL at steady state.

Distribution

Apparent Vd _ss is 3 to 5 L/kg. Protein binding is 99%.

Metabolism

Metabolism takes place in the liver by oxidation via CYP-450 3A4 isoenzyme, aromatic hydroxylation, and conjugation with glucuronic acid and/or sulphate.

Elimination

The t _{1/ 2} is about 40 days. Cl is about 690 mL/min. Fulvestrant is cleared by the hepatobiliary route; renal elimination is less than 1%. It is primarily excreted in the feces (about 90%).

Indications and Usage

Treatment of hormone receptor-positive metastatic breast cancer in postmenopausal women with disease progression following antiestrogen therapy.

Contraindications

Pregnancy; hypersensitivity to the drug or any component of the product.

Dosage and Administration

Adults

IM 250 mg into buttock at 1-mo intervals using prefilled syringe(s) and supplied safety needle(s).

General Advice

• For IM administration only. Not for IV, SC, or ID administration.
• Administer as single 5 mL injection or concurrent 2.5 mL injections into buttock.
• Do not administer if cloudiness or particulate matter is noted.

Storage/Stability

Store prefilled syringes in refrigerator (36° to 46°F).

Drug Interactions

None well documented.

Laboratory Test Interactions

None well documented.

Adverse Reactions

CNS

Headache; dizziness; insomnia; paresthesia; depression; anxiety.

Dermatologic

Rash; sweating.

EENT

Pharyngitis.

GI

Nausea; vomiting; constipation; diarrhea; abdominal pain; anorexia.

Genitourinary

Urinary tract infection.

Hematologic

Anemia.

Respiratory

Dyspnea; increased cough.

Miscellaneous

Back pain; hot flushes; bone pain; arthritis; asthenia; pain; transient pain and inflammation at injection site; vasodilation; pelvic pain; peripheral edema; chest pain; flu-like syndrome; fever; accidental injury.

Precautions

Pregnancy

Category D .

Lactation

Undetermined.

Children

Safety and efficacy not established.

Patient Information

• Advise patient that medication will be prepared and administered by health care provider in a health care setting on a monthly basis.
• Instruct patient to inform health care provider if any of the following symptoms occur: intolerable nausea, vomiting, constipation, diarrhea, stomach pain, headache, hot flushes, injection site pain or inflammation.