Tamoxifen Dosage

Medically reviewed by Drugs.com. Last updated on Jun 24, 2021.

Usual Adult Dose for Breast Cancer

Metastatic breast cancer in women and men:
20 to 40 mg orally daily for 5 years; doses greater than 20 mg should be given in divided doses (morning and evening)

DCIS following breast surgery and radiation:
20 mg orally daily for 5 years

To reduce the incidence of breast cancer in women at high risk for breast cancer:
20 mg orally daily for 5 years

Comments:

• There are no data to support the use of this drug other than for 5 years.

Uses:

• Metastatic For metastatic breast cancer in women and men. In premenopausal women with metastatic breast cancer, this drug is an alternative to oophorectomy or ovarian irradiation. Patients whose tumors are estrogen receptor positive are more likely to benefit.
• Ductal Carcinoma in Situ (DCIS): In women with DCIS, following breast surgery and radiation, to reduce the risk of invasive breast cancer.
• Reduction in Breast Cancer Incidence in High Risk Women: To reduce the incidence of breast cancer in women at high risk. "High risk" is defined as women at least 35 years of age with a 5-year predicted risk of breast cancer greater than or equal to 1.67%, as calculated by the Gail Model.

Usual Adult Dose for Breast Cancer - Adjuvant

20 mg orally once daily or 10 mg orally 2 times daily
Duration of therapy: Up to 5 years

Comments:

• There are no data to support the use of this drug other than for 5 years.

Use: For the treatment of node-positive breast cancer in postmenopausal women following total mastectomy or segmental mastectomy, axillary dissection, and breast irradiation

Usual Pediatric Dose for McCune-Albright Syndrome

Girls 2 to 10 years with McCune-Albright Syndrome and precocious puberty:
20 mg orally once daily
Duration of therapy: Up to 12 months

Use: McCune-Albright Syndrome; precocious puberty

Usual Pediatric Dose for Precocious Puberty

Girls 2 to 10 years with McCune-Albright Syndrome and precocious puberty:
20 mg orally once daily
Duration of therapy: Up to 12 months

Use: McCune-Albright Syndrome; precocious puberty

Renal Dose Adjustments

Data not available

Liver Dose Adjustments

Data not available

Precautions

US BOXED WARNINGS:
Women with Ductal Carcinoma in Situ (DCIS) and Women at High Risk for Breast Cancer:

• Serious and life-threatening events associated with this drug in the risk reduction setting (women at high risk for cancer and women with DCIS) include uterine malignancies, stroke, and pulmonary embolism. Uterine malignancies consist of both endometrial adenocarcinoma and uterine sarcoma.
• Some of the strokes, pulmonary emboli, and uterine malignancies were fatal.
• Health care providers should discuss the potential benefits versus risks of these events with women at high risk of breast cancer and women with DCIS considering this drug to reduce their risk of developing breast cancer.
• The benefits of this drug outweigh its risks in women already diagnosed with breast cancer.

CONTRAINDICATIONS:

• Hypersensitivity to the active component or any of the ingredients
• In women who require concomitant coumarin-type anticoagulant therapy or in women with a history of deep-vein thrombosis or pulmonary embolus

Safety and efficacy have not been established in male patients younger than 18 years.

Safety and efficacy have not been established in female patients younger than 2 years for McCune-Albright Syndrome and precocious puberty, or female patients 10 years to 18 years for McCune-Albright Syndrome and precocious puberty.

Consult WARNINGS section for additional precautions.

Dialysis

Data not available

Other Comments

Patient advice:

• Swallow the tablet whole, with water or another non-alcoholic liquid.
• This drug can be taken with or without food.
• If a dose is forgotten, take it when you remember, then take the next dose as usual. If it is almost time for your next dose or you remember at your next dose, do not take extra tablets to make up the missed dose.
• Take this drug for 5 years, unless your doctor tells you otherwise.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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