Estramustine belongs to the group of cancer-fighting medications known as antineoplastics. It is made up of 2 different types of medications joined together: mechlorethamine and estrogen. Mechlorethamine belongs to a group of medications known as alkylating agents. Estrogen is a female hormone. Estramustine is used to treat cancer of the prostate that has spread and is not responding to other treatments.

The mechlorethamine portion of estramustine prevents the growth of cancer cells by interfering with the genetic material DNA, which is necessary for reproduction of cells. After estramustine is broken down or metabolized by the body, estrogen is released. The estrogen component of estramustine slows down the growth of prostate cancer cells. This medication may need to be taken for several weeks or months in order to be effective.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

The dose is specific for a patient's body size and weight. The recommended dose is usually divided into 3 or 4 doses per day. Estramustine capsules should be taken on an empty stomach at least 1 hour before or 2 hours after meals. They should be swallowed whole with water and should not be taken at the same time as milk, milk products, or calcium-containing drugs such as certain antacids.

Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

It is important to take this medication exactly as prescribed by your doctor. If you feel ill after taking it, do not stop taking it without talking with your doctor first. If you vomit shortly after taking a dose of medication, check with your doctor to find out if you should take another dose or wait for the next scheduled dose.

If you miss a dose of this medicine, skip the missed dose and go back to your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication in a cool, dry place, protect it from light and moisture, and keep it out of the reach of children.

Do not take estramustine if you:

• are sensitive or allergic to estradiol (an estrogen), nitrogen mustard, or any ingredients of this medication
• have active thrombophlebitis or thromboembolic disorders (blood clotting disorders)
• have severe liver disease or heart disease

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• breast tenderness or enlargement
• decreased interest in sex
• decreased sexual ability
• diarrhea
• headache
• muscle weakness
• nausea
• stomach upset
• vomiting

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• confusion
• signs of anemia (low red blood cells; e.g., dizziness,  pale skin, unusual tiredness or weakness, shortness of breath)
• signs of a blood clot in the arm or leg (tenderness, pain, swelling, warmth, or redness in the arm or leg) or lungs (difficulty breathing, sharp chest pain that is worst when breathing in, coughing, coughing up blood, sweating, or passing out)
• signs of clotting problems (e.g., unusual nosebleeds, bruising, blood in urine, coughing blood, bleeding gums, cuts that don’t stop bleeding)
• signs of depression (e.g., poor concentration, changes in weight, changes in sleep, decreased interest in activities, thoughts of suicide)
• signs of very high blood pressure (e.g., headache, dizziness, blurred vision, nausea, vomiting or shortness of breath)
• signs of infection (symptoms may include fever or chills, severe diarrhea, shortness of breath, prolonged dizziness, headache, stiff neck, weight loss, or listlessness)
• signs of liver problems (e.g., nausea, vomiting, diarrhea, loss of appetite, weight loss, yellowing of the skin or whites of the eyes, dark urine, pale stools)
• swelling of feet or lower legs
• unusual tiredness or weakness

Stop taking the medication and seek immediate medical attention if any of the following occur:

• signs of a serious allergic reaction (e.g., abdominal cramps, difficulty breathing, nausea and vomiting, or swelling of the face and throat)
• signs of bleeding in the stomach (e.g., bloody, black, or  tarry stools, spitting up of blood, vomiting blood or material that looks like coffee grounds)
• signs of heart attack (e.g., sudden chest pain or pain radiating to back, down arm, jaw; sensation of fullness of the chest; nausea; vomiting; sweating; anxiety)
• signs of stroke (e.g., sudden or severe headache; sudden loss of coordination; vision changes; sudden slurring of speech; or unexplained weakness, numbness, or pain in arm or leg)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Before you begin taking a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should take this medication.

Blood vessel conditions: The risk and benefits of using this medication for people with a history of thrombophlebitis or other blood clotting problems should be reviewed with a doctor. If you have vascular problems in the brain (such as a history of stroke) or coronary artery disease, discuss the risks and benefits of using this medication with your doctor.

Calcium: This medication can influence the balance of calcium and phosphorus in the body, which may affect certain other medical conditions in addition to prostate cancer. If you have certain bone diseases or cancer that has spread to the bone, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed. Your doctor may want you to have your calcium levels tested regularly with blood tests while you are taking estramustine.

Contraception: Men receiving estramustine should use appropriate contraceptive measures (e.g., latex condoms) with their female partners since this medication can cause serious problems in an unborn child.

Diabetes: Estramustine can cause loss of control of blood glucose levels and glucose tolerance may change. People with diabetes may find it necessary to monitor their blood sugar more frequently while using this medication.

If you have diabetes or are at risk for developing diabetes, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Fluid retention: Estramustine may worsen fluid retention, congestive heart failure, and other conditions affected by fluid retention (e.g., epilepsy, migraine, and kidney impairment). Your doctor will monitor you for these problems when necessary.

High blood pressure: Estramustine may increase blood pressure. If you have high blood pressure before starting this medication, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed. You should regularly monitor your blood pressure.

Infection: As well as killing cancer cells, estramustine can reduce the number of cells that fight infection in the body (white blood cells). If possible, avoid contact with people with contagious infections. Tell your doctor immediately if you notice signs of an infection, such as fever or chills, severe diarrhea, shortness of breath, prolonged dizziness, headache, stiff neck, weight loss, or listlessness. Your doctor will do blood tests regularly to monitor the number of specific types of blood cells in your blood.

Vaccines: You should not be given live vaccines, or be in contact with any person who has received live vaccines, as this may result in serious infections and death. You doctor can tell you which vaccines are safe.

Pregnancy: The safety and effectiveness of using this medication during pregnancy have not been established. Medications similar to estramustine are known to cause harm to an unborn child. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: It is not known if estramustine passes into breast milk. If you are a breast-feeding mother and are taking this medication, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of using this medication have not been established for children.

There may be an interaction between estramustine and any of the following:

• amphotericin B
• anabolic steroids
• androgens (male hormones; e.g., methyltestosterone, nandrolone, testosterone)
• calcium and products containing calcium (e.g., antacids, vitamins)
• clodronate
• denosumab
• echinacea
• estrogens (female hormones)
• fingolimod
• leflunomide
• natalizumab
• pimecrolimus
• roflumilast
• tacrolimus
• tofacitinib
• trastuzumab
• vaccines

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.