Generic
Tamoxifen
13 brands available in the market
At a glance
Tamoxifen is an anti-estrogen drug used for breast cancer treatment and reducing breast cancer risk in high-risk women. It blocks estrogen effects in breast tissue by binding to estrogen receptors.
Description
Tamoxifen is a triphenylethylene derivative that competitively binds to estrogen receptors, blocking estrogen effects in breast tumors and other tissues. It decreases DNA synthesis and arrests cells in G0 and G1 phases, exhibiting cytostatic activity. It also helps maintain bone mineral density in postmenopausal women.
Indications
- Breast cancer treatment (ER-positive)
- Breast cancer prevention in high-risk women
- Anovulatory infertility
Therapeutic class
Hormonal Chemotherapy
Pharmacological class
Selective Estrogen Receptor Modulator (SERM)
Pharmacology
Tamoxifen competitively binds to estrogen receptors, blocking estrogen-dependent tumor cell growth. It decreases DNA synthesis and arrests cells in G0 and G1 phases of the cell cycle, reducing cell division. It also helps maintain bone mineral density in postmenopausal women.
Mechanism of action
Slows breast cancer cell growth by blocking estrogen receptors.
Dosage
Adult Dose (Oral):
- Breast cancer: 20 mg/day (single or 2 divided doses); max 40 mg/day; adjuvant therapy for at least 5 years (up to 10 years recommended)
- Breast cancer prevention: 20 mg/day for 5 years
- Anovulatory infertility: 20 mg/day (days 2-5 of cycle); may increase to 40-80 mg/day
Administration
- Take with or without food
- Swallow tablet whole; do not chew, crush, or break
- Take at the same time each day
- Do not stop without your doctor's advice
Missed dose
If you miss a dose, take it as soon as you remember; if almost time for the next dose, skip it; do not double the dose.
Side effects
Common Side Effects:
- Nausea, skin rash
- Hot flashes, hair thinning
- Vaginal discharge, edema
- Headache, light-headedness
Serious:
- DVT, pulmonary embolism (thromboembolic events)
- Endometrial cancer (monitor for vaginal bleeding)
- Hypercalcemia (in bone metastases)
Precautions & warnings
- Do not use in history of DVT or pulmonary embolism
- Do not use in pregnancy and lactation
- Investigate any abnormal gynecological symptoms (vaginal bleeding)
- Birth control pills are less effective; use condoms
- Monitor liver function and calcium levels
Contraindications
- History of DVT or pulmonary embolism
- Pregnancy and lactation
- Concomitant coumarin-type anticoagulant therapy
- Hypersensitivity to tamoxifen
Drug interactions
- Bromocriptine: Increased dopaminergic effect
- Cytotoxic drugs: Increased risk of thromboembolic events
- Coumarin anticoagulants (warfarin): Significantly increased anticoagulant effect (potentially fatal)
- CYP3A4 inducers: Decreased tamoxifen levels
- CYP3A4 inhibitors: Increased levels
Food interactions
Alcohol is unsafe with Tamoxifen (increased liver risk).
Use in pregnancy
Use in Pregnancy: Highly unsafe (Category D); significant risk to developing baby; do not use; consult your doctor.
Pregnancy Category: X — always consult a doctor before taking during pregnancy.
Use in lactation
Use in Lactation: Probably unsafe; drug may pass into breast milk and harm the baby; do not use; consult your doctor.
Pediatric use
Safety and efficacy not established in children
Geriatric use
Indicated for elderly
Renal / hepatic impairment
Renal Impairment: Safe in kidney disease; dose adjustment may not be needed; consult your doctor.
Hepatic Impairment: Limited information; consult your doctor.
Overdose effects
No specific antidote for overdose; provide symptomatic and supportive treatment.
Storage conditions
Store at 20-25°C, protected from light; keep out of reach of children.
Chemical structure
Tamoxifen