Why is Tamoxifen prescribed?

Tamoxifen, an anticancer drug, is given to treat breast cancer. It also has proved effective when cancer has spread to other parts of the body. Tamoxifen is most effective in stopping the kind of breast cancer that thrives on estrogen.

Tamoxifen is also prescribed to reduce the risk of invasive breast cancer following surgery and radiation therapy for ductal carcinoma in situ. The drug can also be used to reduce the odds of breast cancer in women at high risk of developing the disease. It does not completely eliminate your chances, but in a five-year study of over 1,500 high-risk women, it slashed the number of cases by 44 percent.

Most important fact about Tamoxifen

Although Tamoxifen reduces the risk of breast cancer, it increases othe possibility of developing endometrial (uterine) cancer. Women taking Tamoxifen should have routine gynecological examinations and report any abnormal vaginal bleeding, changes in menstrual periods, change in vaginal discharge, or pelvic pain or pressure to the doctor immediately. Even after Tamoxifen therapy has stopped, any abnormal vaginal bleeding should be reported at once.

How should you take Tamoxifen?

Take Tamoxifen exactly as prescribed. Do not stop taking Tamoxifen without first consulting your doctor. It may be necessary to continue taking the drug for several years.

If you miss a dose: Do not try to make it up. Go back to your regular schedule with the next dose.

Storage instructions: Tamoxifen may be stored at room temperature.

What side effects may occur?

Side effects from Tamoxifen are usually mild and rarely require the drug to be stopped. If any develop or change in intensity, inform your doctor as soon as possible. Only your doctor can determine if it is safe for you to continue taking Tamoxifen.

• More common side effects may include:
  Hot flashes, nausea, vomiting

Why should Tamoxifen not be prescribed?

Do not take Tamoxifen if you are sensitive to it or have ever had an allergic reaction to it.

If you are taking the blood-thinning drug Coumadin or have had problems with clots in your veins or your lungs, you should not take Tamoxifen to reduce the risk of breast cancer, and when taking it to treat an actual case of the disease, you should use it with caution.

Special warnings about Tamoxifen

In addition to increasing the risk of uterine cancer, Tamoxifen also raises the odds of developing endometriosis (the spread of endometrial tissue outside the uterus), uterine fibroids, uterine polyps, and ovarian cysts. Women who take Tamoxifen also face a greater risk of stroke and blood clots lodging in their lungs. The risk increases further when Tamoxifen is combined with toxic cancer drugs. Tamoxifen can also cause liver damage, and should be used with caution if you already have liver problems.

If you experience visual problems while taking Tamoxifen, notify your doctor immediately.

In a few women Tamoxifen may raise the level of cholesterol and other fats in the blood. Your doctor may periodically do blood tests to check your cholesterol and triglyceride levels.

Tamoxifen may produce an abnormally high level of calcium in the blood. Symptoms include muscle pain and weakness, loss of appetite, and, if severe, kidney failure. If you experience any of these symptoms, notify your doctor as soon as possible.

If tests show that your blood contains too few white blood cells or platelets while you are taking Tamoxifen, your doctor should monitor you with special care. These problems have sometimes been found in women taking Tamoxifen; whether the drug caused the blood-cell abnormalities is uncertain.

Possible food and drug interactions when taking Tamoxifen

If Tamoxifen is taken with certain other drugs, the effects of either could be increased, decreased, or altered. It is especially important to check with your doctor before combining Tamoxifen with the following:

Aminoglutethimide (Cytadren)
Blood-thinning drugs such as Coumadin
Bromocriptine (Parlodel)
Cancer drugs such as Cytoxan
Letrozole (Femara)
Phenobarbital
Rifampin (Rifadin)

Special information if you are pregnant or breastfeeding

It is important to avoid pregnancy while taking Tamoxifen, because the drug could harm the unborn child. Since Tamoxifen is an anti-estrogen drug, you will need to use a non-hormonal form of contraception, such as a condom and/or diaphragm, and not birth control pills. If you accidentally become pregnant while taking Tamoxifen, or within 2 months after you have stopped taking it, discuss this with your doctor immediately.

Because Tamoxifen might cause serious harm to a nursing infant, you should not breastfeed your baby while taking Tamoxifen. If Tamoxifen is essential to your health, your doctor may advise you to discontinue breastfeeding until your treatment is finished.

Recommended dosage

ADULTS

Breast Cancer Treatment

The daily dosage ranges from 20 to 40 milligrams. If you are taking more than 20 milligrams a day, your doctor will have you divide the total into 2 smaller doses taken in the morning and evening. Tamoxifen comes in 10- and 20-milligram tablets.

Ductal Carcinoma in Situ

The recommended dose is 20 milligrams once daily for 5 years.

Breast Cancer Prevention

The recommended dose is 20 milligrams once a day for up to 5 years.

CHILDREN

Safety and efficacy in children have not been established.

Overdosage

Any medication taken in excess can have serious consequences. If you suspect an overdose of Tamoxifen, seek medical attention immediately.

• Symptoms of Tamoxifen overdose may include:
  Dizziness, overactive reflexes, tremor, unsteady gait