• Increased risk of venous thromboembolism and stroke – higher risk with chemotherapy, surgery, or prior clot history
• Risk of endometrial pathology (hyperplasia, polyps, endometrial cancer) – investigate any vaginal bleeding immediately
• Contraindicated in pregnancy and breastfeeding – teratogenic
• Visual disturbances and cataracts may occur – ophthalmology review if symptoms develop
• Hypercalcaemia can occur, especially in patients with bone metastases
• Interacts with CYP2D6 inhibitors (e.g. paroxetine, fluoxetine) – may reduce efficacy
• Tumour flare may occur early in treatment
• Avoid in patients with active or high-risk thromboembolic disease unless benefits outweigh risks
Generic name: Tamoxifen (as tamoxifen citrate)
Brand name: TAMOPLEX®
Drug class: Selective oestrogen receptor modulator (SERM)
Formulation: Oral tablets
Strength: 20 mg
Scheduling status: S4
Mechanism of action:
Tamoxifen acts as an oestrogen antagonist in breast tissue by competitively binding to oestrogen receptors, inhibiting oestrogen-mediated tumour growth. It has partial agonist effects in bone and endometrium.
Breast cancer:
• Treatment of breast cancer in adult patients
Adults (including elderly):
• 20 mg orally once daily
Administration:
• Swallow tablet whole with water
• Do not crush or chew
• Duration of treatment is determined by the treating clinician
Children:
• Not recommended
• No routine dose adjustment required
• Interrupt or discontinue if severe thromboembolic events, severe visual disturbance, or significant endometrial pathology occurs
• Clinical judgement required in patients with hepatic dysfunction or low blood counts
• Hypersensitivity to tamoxifen or any excipients
• Premenopausal status
• Pregnancy or breastfeeding
• Monitor for signs of thromboembolism (leg swelling, chest pain, dyspnoea)
• Gynaecological review if vaginal bleeding, pelvic pain, or menstrual irregularities occur
• Visual symptoms – assess for cataracts or retinal changes
• Periodic blood counts if clinically indicated
• Monitor calcium levels in patients with bone metastases
Very common and common:
• Hot flushes
• Nausea and vomiting
• Fatigue
• Headache
• Alopecia
• Vaginal irritation or discharge
• Menstrual irregularities
• Muscle pain and leg cramps
• Weight gain
• Endometrial hyperplasia
Serious:
• Venous thromboembolism (DVT, PE)
• Stroke or transient ischaemic attack
• Endometrial cancer
• Severe visual disturbance or loss of vision
• Hepatotoxicity
• Interstitial pneumonitis
• Severe allergic reactions
• Anticoagulants (e.g. warfarin) – increased bleeding risk
• CYP2D6 inhibitors (e.g. paroxetine, fluoxetine, bupropion, quinidine) – reduced tamoxifen efficacy
• Rifampicin – reduced tamoxifen levels
• Other cytotoxic chemotherapy – increased thromboembolic risk
• Pregnancy: Contraindicated
• Breastfeeding: Contraindicated
• Premenopausal women: Contraindicated
• Elderly: No dose adjustment required
• Hepatic impairment: Use with caution
• Renal impairment: No specific adjustment required
Continue treatment for the duration prescribed by the treating clinician.
Permanently discontinue if:
• Venous or arterial thromboembolic event occurs
• Endometrial malignancy develops
• Severe visual toxicity occurs
• Pregnancy is confirmed
**Usually discontinued after 5 years - can be given upto 10 years
| Trade Name | |
|---|---|
| Drug Class | Selective Estrogen Receptor Modulators (SERMs) |
| Cost | |
| Company | |
|---|---|
| Drug Rep | Admin |
| Indications | Breast Cancer |
| Dosage |