Name: Soltamox

Why is this medication prescribed?

Tamoxifen is used to treat breast cancer that has spread to other parts of the body in men and women. It is used to treat early breast cancer in women who have already been treated with surgery, radiation, and/or chemotherapy. It is used to reduce the risk of developing a more serious type of breast cancer in women who have had ductal carcinoma in situ (DCIS; a type of breast cancer that does not spread outside of the milk duct where it forms) and who have been treated with surgery and radiation. It is used to reduce the risk of breast cancer in women who are at high risk for the disease due to their age, personal medical history, and family medical history.

Tamoxifen is in a class of medications known as antiestrogens. It blocks the activity of estrogen (a female hormone) in the breast. This may stop the growth of some breast tumors that need estrogen to grow.

What special precautions should I follow?

Before taking tamoxifen,

  • tell your doctor and pharmacist if you are allergic to tamoxifen or any other medications.
  • tell your doctor and pharmacist what prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or plan to take. Be sure to mention any of the following: aminoglutethimide (Cytadren); anastrazole (Arimidex), bromocriptine (Parlodel); cancer chemotherapy medication such as cyclophosphamide (Cytoxan, Neosar) letrozole (Femara); medroxyprogesterone (Depo-Provera, Provera, in Prempro); phenobarbital; and rifampin (Rifadin, Rimactane). Your doctor may need to change the doses of your medications or monitor you carefully for side effects.
  • in addition to the conditions listed in the IMPORTANT WARNING section, tell your doctor if you have or have ever had high blood levels of cholesterol.
  • tell your doctor if you are pregnant or plan to become pregnant. You should not plan to become pregnant while taking tamoxifen or for 2 months after your treatment. Your doctor may perform a pregnancy test or tell you to begin your treatment during your menstrual period to be sure that you are not pregnant when you begin taking tamoxifen. You will need to use a reliable nonhormonal method of birth control to prevent pregnancy while you are taking tamoxifen and for 2 months after your treatment. Talk to your doctor about the types of birth control that are right for you, and continue to use birth control even if you do not have regular menstrual periods during your treatment. Stop taking tamoxifen and call your doctor right away if you think you have become pregnant during your treatment. Tamoxifen may harm the fetus.
  • tell your doctor if you are breast-feeding. You should not breastfeed during your treatment with tamoxifen.
  • tell all of your doctors and other health care providers that you are taking tamoxifen.
  • you will still need to look for early signs of breast cancer since it is possible to develop breast cancer even during treatment with tamoxifen. Talk to your doctor about how often you should examine your breasts yourself, have a doctor examine your breasts, and have mammograms (x-ray examinations of the breasts). Call your doctor right away if you find a new lump in your breast.

Dosing & Uses

Dosage Forms & Strengths

tablet (generic)

  • 10mg
  • 20mg

oral solution

  • 10mg/5mL (Soltamox)

Breast Cancer Treatment

20-40 mg/day PO; doses >20mg/day should be divided BID (ie, morning and evening)

Although the FDA has approved a dosage range of 20-40 mg/day, clinical benefit for doses >20 mg/day has not been demonstrated

Continue with adjuvant therapy for at least 5 years

For women with ER-positive disease, continuing tamoxifen to 10 years rather than stopping at 5 years produces a further reduction in recurrence and mortality, particularly after year 10 (ATLAS trial, Lancet 2013;381:805-816; aTTom trial; ASCO Annual Meeting 2013;31:5)

Treatment indications

  • Treatment of metastatic breast cancer in women and men; in premenopausal women, alternative to oophorectomy or ovarian irradiation; estrogen receptor positive tumors more likely to benefit
  • Adjuvant treatment of node-positive breast cancer in postmenopausal women following total mastectomy or segmental mastectomy, axillary dissection, and breast irradiation; most benefit in the subgroup with 4 or more positive axillary nodes
  • Adjuvant treatment of axillary node-negative breast cancer in women following total mastectomy or segmental mastectomy, axillary dissection, and breast irradiation
  • Reduces occurrence of contralateral breast cancer in patients receiving adjuvant treatment

Ductal Carcinoma in Situ

Indicated in women with ductal carcinoma in situ following breast surgery and radiation to reduce the risk of invasive breast cancer

20 mg PO qDay for 5 years

Breast Cancer Prevention

Indicated to reduce the incidence of breast cancer in women at high risk for breast cancer; high risk is defined as women aged ≥35 years with a 5-year predicted risk of breast cancer ≥1.67% (calculated by the Gail Model)

20 mg PO qDay for 5 years

Data are limited for use >5 yr in the risk-reduction setting (NCCN guidelines)

Ovulation Induction (Off-label)

5-40 mg PO q12hr for 4 days

Mastalgia (Off-label)

10 mg PO qDay for 4 months

Other Indications & Uses


Safety and efficacy not established


Black Box Warnings

For women with ductal carcinoma in situ (DCIS) and women at high risk for breast cancer:

Uterine malignancies, stroke, and pulmonary embolism reported with use in risk-reduction setting (women with ductal carcinoma in situ and women at high risk for breast cancer).




Undiagnosed vaginal bleeding

History of thromboembolism (prevention, DCIS)

Coumarin anticoagulation (prevention, DCIS)


History of thromboembolism (CA treatment); tamoxifen significantly increases risk of venous thromboembolism

Coumarin anticoagulation (CA treatment)

CYP2D6 polymorphism-CYP2D6 converts tamoxifen to active metabolite endoxifen; lowered CYP2D6 activity or concomitant CYP2D6 inhibitors may reduce tamoxifen efficacy

Bone metastases


Cholestasis, fatty liver, hepatic necrosis, and hepatitis reported


Postmarketing cases of hyperlipidemia reported

Decreased visual acuity, corneal changes, retinal vein thrombosis

Flushing and increased bone pain and/or tumor pain sometimes associated with good tumor response

Chronic use for prevention may result in increased risk of stroke, pulmonary embolism, endometrial cancer, uterine sarcoma, cataract

Avoid pregnancy

Uses of Soltamox

Soltamox is a prescription medicine used:

  • to lower the risk of getting breast cancer in women with a higher than normal risk of getting breast cancer in the next 5 years (high-risk women)
  • to lower the risk of getting invasive (spreading) breast cancer in women who had surgery and radiation for ductal carcinoma in situ (DCIS); DCIS means the cancer is only inside milk ducts
  • to treat breast cancer in women after they have finished early treatment. Early treatment can include surgery, radiation, and chemotherapy
  • in women and men to treat breast cancer that has spread to other parts of the body (metastatic breast cancer)

This medication may be prescribed for other uses. Ask your doctor or pharmacist for more information.


  • DARA BioSciences, Inc.

What should I discuss with my healthcare provider before taking Soltamox (tamoxifen)?

You should not use tamoxifen if you are allergic to it.

You should not use tamoxifen to reduce your risk of breast cancer if you are also taking a blood thinner such as warfarin (Coumadin, Jantoven).

Do not take tamoxifen if you are pregnant. It could harm the unborn baby. Avoid becoming pregnant while you are using this medicine, and for at least 2 months after your treatment ends.

Hormonal contraception (such as birth control pills, injections, implants, skin patches, and vaginal rings) may not be effective enough to prevent pregnancy while taking tamoxifen. Ask your doctor about using non hormonal birth control (condom, diaphragm with spermicide, or intrauterine device/IUD).

If you are taking tamoxifen to reduce your risk of breast cancer, you may need to take your first dose while you are having a menstrual period. You may also need to have a pregnancy test before you start taking tamoxifen, to make sure you are not pregnant. Follow your doctor's instructions.

Taking tamoxifen may increase your risk of uterine cancer, stroke, or a blood clot in the lung, which can be fatal. Talk with your doctor about your specific risks in taking this medicine.

To make sure tamoxifen is safe for you, tell your doctor if you have:

  • a history of stroke or blood clot;

  • liver disease;

  • high cholesterol or triglycerides (a type of fat in the blood);

  • a history of cataracts; or

  • if you are receiving chemotherapy or radiation.

It is not known whether tamoxifen passes into breast milk or if it could harm a nursing baby. This medicine may slow breast milk production. You should not breast-feed while taking tamoxifen.

Uses For Soltamox

Tamoxifen is a medicine that blocks the effects of the estrogen hormone in the body. It is used to treat breast cancer in women or men. It may also be used to treat other kinds of cancer, as determined by your doctor.

Tamoxifen also may be used to reduce the risk of developing breast cancer in women who have a high risk of developing breast cancer. Women at high risk for developing breast cancer are at least 35 years of age and have a combination of risk factors that make their chance of developing breast cancer 1.67% or more over the next 5 years. Your doctor will help to determine your risk of developing breast cancer.

    The following are risk factors that may increase your chance of developing breast cancer:
  • If you have close family members (mother, sister, or daughter) with breast cancer.
  • If you have ever had a breast biopsy or if high-risk changes in your breast(s) have been found from a breast biopsy.
  • If you have never been pregnant or if your first pregnancy occurred at a late age.
  • If your first menstrual period occurred at an early age.

The exact way that tamoxifen works against cancer is not known, but it may be related to the way it blocks the effects of estrogen on the body.

Before you begin treatment with tamoxifen, you and your doctor should talk about the good this medicine will do as well as the risks of using it.

Tamoxifen is available only with your doctor's prescription.

What are some side effects that I need to call my doctor about right away?

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

  • Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.
  • Signs of high calcium levels like weakness, confusion, feeling tired, headache, upset stomach and throwing up, hard stools (constipation), or bone pain.
  • Weakness on 1 side of the body, trouble speaking or thinking, change in balance, drooping on one side of the face, or blurred eyesight.
  • Change in eyesight.
  • Any unexplained bruising or bleeding.
  • A lump in the breast or breast soreness.
  • Low mood (depression).
  • Feeling very tired or weak.
  • Fever or chills.
  • Sore throat.
  • Swelling.
  • Any skin change.
  • Very bad headache.
  • Call your doctor right away if you have signs of a blood clot like chest pain or pressure; coughing up blood; shortness of breath; swelling, warmth, numbness, change of color, or pain in a leg or arm; or trouble speaking or swallowing.
  • Very bad and sometimes deadly liver problems have happened with Soltamox. Call your doctor right away if you have signs of liver problems like dark urine, feeling tired, not hungry, upset stomach or stomach pain, light-colored stools, throwing up, or yellow skin or eyes.
  • If you are a woman, call your doctor right away if you have pain when passing urine, pelvic pain or pressure, period (menstrual) changes like no period, vaginal bleeding that is not normal, or vaginal discharge.
  • Some men have had sexual problems when taking this medicine. These include lowered interest in sex and not able to get an erection. Call your doctor right away if you have sexual problems when taking Soltamox (tamoxifen solution).

Soltamox Description

Soltamox™ solution, a nonsteroidal antiestrogen, is for oral administration. Each 5 mL solution contains 10 mg tamoxifen, equivalent to 15.2 mg tamoxifen citrate and the following inactive ingredients: ethanol, glycerol, propylene glycol, sorbitol solution, licorice flavor, aniseed flavor, purified water.

The chemical name is (Z)2-[4-(1,2-diphenyl-l-butenyl) phenoxy]-N,N-dimethylethanamine 2-hydroxy-1,2,3- propanetricarboxylate (1:1). The structural and empirical formulas are:

Tamoxifen citrate has a molecular weight of 563.62, the pKa' is 8.85, the equilibrium solubility in water at 37°C is 0.5 mg/mL and in 0.02 N HCl at 37°C, it is 0.2 mg/mL.