Testolactone

(tess-tuh-lak-tone)

Trade/other name(s): Teslac

Why would this drug be used?

Testolactone is used to treat breast cancer in women who have gone through menopause (no longer have menstrual periods).

How does this drug work?

Testolactone belongs to the general group of drugs known as hormone antagonists. Its action is not fully understood, but it helps keep the body from making estrone (a type of estrogen that is more plentiful after menopause) by inhibiting the enzyme aromatase.

Before taking this medicine

Tell your doctor…

• If you are allergic to anything, including medicines, dyes, additives, or foods.
• If you have any medical conditions such as kidney disease, liver disease (including hepatitis), heart disease, congestive heart failure, diabetes, gout, or infections. These conditions may require that your medicine dose, regimen, or timing be changed.
• If you are pregnant, trying to get pregnant, or if there is any chance of pregnancy. There may be an increased risk of birth defects if a woman takes this drug during pregnancy.
• If you are breast-feeding. It is not known whether this drug passes into breast milk. If it does, it could harm the baby.
• If you think you might want to have children in the future. It is not known whether or not this drug can affect fertility. It is only approved for use in women who are menopausal. Talk with your doctor about the possible risk with this drug and any options that may preserve your ability to have children.
• About any other prescription or over-the-counter medicines you are taking, including vitamins and herbs. In fact, keeping a written list of each of these medicines (including the doses of each and when you take them) with you in case of emergency may help prevent complications if you get sick.

Interactions with other drugs

This drug may cause anticoagulants (blood thinners such as warfarin) to become more active. This can increase your risk of bleeding.

Check with your doctor, nurse, or pharmacist about other medicines, vitamins, herbs, and supplements, and whether alcohol can cause problems with this medicine.

Interactions with foods

No serious interactions with food are known at this time. Check with your doctor, nurse, or pharmacist about whether foods may be a problem.

Tell all the doctors, dentists, nurses, and pharmacists you visit that you are taking this drug.

How is this drug taken or given?

Testolactone comes in pill form, and is taken by mouth 4 times a day. Take this drug exactly as directed by your doctor. If you do not understand the instructions, ask your doctor or nurse to explain them to you. Store the medicine in a tightly closed container and away from children and pets.

Precautions

Testolactone may cause you to retain salt and water. Your doctor may prescribe a diuretic ("water pill"). Tell your doctor or nurse if you gain weight or notice swelling in your feet or ankles.

Testolactone is not to be used in male breast cancer, and has not been tested in children.

Possible side effects

You will probably not have most of the following side effects, but if you have any talk to your doctor or nurse. They can help you understand the side effects and cope with them.

Less common

• nausea
• loss of appetite
• diarrhea
• increase in blood pressure
• skin rash
• body aches
• swelling of the legs and feet*
• swollen red tongue

*See the "Precautions" section for more detailed information.

There are other side effects not listed above that can also occur in some patients. Tell your doctor or nurse if you develop these or any other problems.

FDA approval

Yes – first approved before 1984. (FDA cannot verify dates of drugs approved before 1984.)

Disclaimer: This information does not cover all possible uses, actions, precautions, side effects, or interactions. It is not intended as medical advice, and should not be relied upon as a substitute for talking with your doctor, who is familiar with your medical needs.