In the U.S.—

• Antineoplastic

Samarium Sm 153 lexidronam (sa-MARE-ee-um lex-ID-roe-nam) is a radiopharmaceutical (ray-dee-oh-far-ma-SOO-ti-kal) . Radiopharmaceuticals are radioactive agents that may be used to diagnose some diseases by studying the function of the body's organs or to treat certain diseases.

Samarium Sm 153 lexidronam is used to help relieve the bone pain that may occur with certain kinds of cancer. The radioactive samarium is taken up in the bone cancer area and gives off radiation that helps provide relief of pain.

Samarium Sm 153 lexidronam is to be given only by or under the direct supervision of a doctor with specialized training in nuclear medicine or radiation oncology. It is available in the following dosage form:

Parenteral
• Injection (U.S.)

In deciding to use a medicine, the risks of receiving the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For samarium Sm 153 lexidronam, the following should be considered:

Allergies—Tell your doctor if you have ever had any unusual or allergic reaction to bone tumor–seeking medicines, like samarium Sm 153 lexidronam, or bone-imaging radiopharmaceuticals. Also tell your doctor if you are allergic to any other substances, such as foods, preservatives, or dyes.

Pregnancy—Studies have not been done in either humans or animals. However, to avoid exposing the fetus to radiation, samarium Sm 153 lexidronam is not recommended for use during pregnancy. Be sure you have discussed this with your doctor.

Breast-feeding—Tell your doctor if you are breast-feeding or if you intend to breast-feed during treatment with this medicine. Because samarium Sm 153 lexidronam may cause serious side effects, breast-feeding is generally not recommended while you are receiving this medicine.

Children—Studies on this medicine have been done only in adult patients, and there is no specific information comparing use of samarium Sm 153 lexidronam in children with use in other age groups.

Older adults—Samarium Sm 153 lexidronam has been used in older people and has not been shown to cause different side effects or problems in older people than it does in younger adults.

Other medicines—Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In other cases, your doctor may want to change the dose, or other precautions may be necessary. When you are receiving samarium Sm 153 lexidronam, it is especially important that your doctor know the following:

• If you have ever received radiation therapy or anticancer medicines—Anticancer medicines or radiation therapy may increase the harmful effects of samarium Sm 153 lexidronam on the bone marrow
• Etidronate (e.g., Didronel)—This medicine may prevent samarium Sm 153 lexidronam from working properly

Your doctor may have special instructions for you to follow to get ready for your treatment. If you do not understand them or if you have not received such instructions, check with your doctor in advance.

This radiopharmaceutical may accumulate in your bladder. Therefore, to increase the flow of urine and lessen the amount of radiation to your bladder your doctor may instruct you to drink plenty of liquids before receiving samarium Sm 153 lexidronam and urinate often afterwards.

If you have a problem controlling your bladder, tell your doctor before receiving samarium Sm 153 lexidronam. Special precautions will need to be taken to prevent radiation contamination of clothing, bed linens, and the environment.

Dosing—

The doses of radiopharmaceuticals will be different for different patients and for the different types of treatment. The amount of radioactivity of a radiopharmaceutical is expressed in units called becquerels or curies. The usual adult dose of samarium Sm 153 lexidronam is 37 megabecquerels (1 millicurie) per kg (16.8 megabecquerels [0.45 millicurie] per pound) of body weight. The dose you receive depends on your body size. The amount of radiation received from this medicine by specific areas of the body to treat a disease is many times higher than that from any diagnostic test, such as x-rays and nuclear medicine scans. Repeated doses may be necessary, depending on the kind of disease you have and how your body is responding to treatment.

It is very important that your doctor check your progress at regular visits to make sure that this medicine is working properly and to check for unwanted effects. You may need to have blood tests done regularly.

Follow these guidelines for 12 hours after receiving samarium Sm 153 lexidronam, to help reduce the chance of contaminating other persons or the environment with radiation:

• Use a normal toilet, if available, instead of a urinal.
• Samarium Sm 153 lexidronam is passed mainly in the urine. To prevent contamination of your home environment, flush the toilet twice after using.
• Wipe any spilled urine with a tissue and flush it away.
• Wash your hands after using or cleaning the toilet.
• Wash your clothes and bed linens immediately, if they become soiled with your urine or blood. Wash them separately from other clothes.
• If you cut yourself, wash away any spilled blood.

Samarium Sm 153 lexidronam can temporarily lower the number of white blood cells in your blood, increasing the chance of getting an infection. It can also lower the number of platelets, which are necessary for proper blood clotting. If your blood count becomes abnormally low, there are certain precautions you can take to reduce the risk of infection or bleeding, such as:

• With abnormally low white blood cell counts:
  • If you can, avoid people with infections. Check with your doctor immediately if you think you are getting an infection or if you get a fever or chills, cough or hoarseness, lower back or side pain, or painful or difficult urination.
  • Be careful when using a regular toothbrush, dental floss, or toothpick. Your medical doctor, dentist, or nurse may recommend other ways to clean your teeth and gums. Check with your medical doctor before having any dental work done.
  • Do not touch your eyes or the inside of your nose unless you have just washed your hands and have not touched anything else in the meantime.
• With abnormally low platelet blood counts:
  • Check with your doctor immediately if you notice any unusual bleeding or bruising; black, tarry stools; blood in urine or stools; or pinpoint red spots on your skin.
  • Be careful not to cut yourself when you are using sharp objects such as a safety razor or fingernail or toenail cutters.
  • Avoid contact sports or other situations where bruising or injury could occur.

Along with its needed effects, a medicine may cause some unwanted effects. Blood problems, such as a decrease in the number of white blood cells or platelets, may occur in some patients using samarium Sm 153 lexidronam.

Check with your doctor immediately if any of the following side effects occur:

• More common
  • Black, tarry stools;  blood in urine or stools;  cough or hoarseness;  fever or chills;  lower back or side pain;  painful or difficult urination;  pinpoint red spots on skin;  unusual bleeding or bruising 
  
  

Also, check with your doctor as soon as possible if you notice the following side effect:

• Less common
  • Irregular heartbeat 
  
  

Other side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. However, check with your doctor if any of the following side effects continue or are bothersome:

• Less common
  • Increase in bone pain (transient);  nausea and vomiting 
  
  

Other side effects not listed above may also occur in some patients. If you notice any other effects, check with your doctor.