Iobenguane I-131 is a radiopharmaceutical (RAY dee oh far ma SOO tik al) medicine that is used to treat a certain type of adrenal gland tumor (pheochromocytoma).

Iobenguane I-131 is also used to treat a rare type of nerve cell tumor (paraganglioma) that can spread throughout the body.

Iobenguane I-131 is for use in adults and children who are at least 12 years old.

Iobenguane I-131 may also be used for purposes not listed in this medication guide.

Both men and women using iobenguane I-131 should use effective birth control to prevent pregnancy. Iobenguane I-131 can harm an unborn baby if the mother or father is receiving this medicine.

If you are a woman, keep using birth control for at least 7 months after your last dose. If you are a man, keep using birth control for at least 4 months after your last dose.

Iobenguane I-131 is given as an infusion into a vein. A healthcare provider will give you this injection.

Iobenguane I-131 is usually given within 1 hour before the first in a series of 3 radiologic tests over 5 days. Two additional doses are then given, separated by at least 90 days.

You may be given other medication to help protect your thyroid gland from exposure to the radiation in iobenguane I-131. Keep using iobenguane I-131 for as long as your doctor has prescribed.

Drink at least 2 liters of liquid on the day before you receive iobenguane I-131, and for 1 week afterward. Follow your doctor's instructions about the types of liquids you should drink. Iobenguane I-131 is radioactive and it can cause dangerous effects on your bladder if it is not properly eliminated from your body through urination.

Expect to urinate often during the first few days after your test. This will help rid your body of the radioactive materials.

Iobenguane I-131 can lower your blood cell counts. Your blood will need to be tested often. Your treatments may be delayed based on the results.

Your blood pressure and kidney function will also need to be checked often.

Tell your doctor if you have ever had:

• kidney disease; or

• if you have routine "INR" or prothrombin time tests.

Using iobenguane I-131 may increase your risk of developing other cancers, such as leukemia. Ask your doctor about this risk.

You may need to have a negative pregnancy test before starting this treatment.

Iobenguane I-131 can harm an unborn baby if the mother or the father is receiving this medicine.

• If you are a woman, do not use iobenguane I-131 if you are pregnant. Use effective birth control to prevent pregnancy while you are receiving this medicine and for at least 7 months after your last dose.

• If you are a man, use effective birth control if your sex partner is able to get pregnant. Keep using birth control for at least 4 months after your last dose.

• Tell your doctor right away if a pregnancy occurs while either the mother or the father is receiving iobenguane I-131.

This medicine may affect fertility (ability to have children) in both men and women. However, it is important to use birth control to prevent pregnancy because iobenguane I-131 can harm an unborn baby.

Do not breast-feed while using this medicine, and for at least 80 days after your last dose.

Call your doctor for instructions if you miss an appointment for your iobenguane I-131 injection.

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

For a short time after you receive iobenguane I-131, your body can give off radiation. For at least 1 week after each dose, avoid having contact with other people as much as possible (especially children and pregnant women). Avoid sharing an eating utensil or drinking glass with another person. Wash your hands with soap and water after each time you use the bathroom.

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Iobenguane I-131 may cause serious side effects. Call your doctor at once if you have:

• chest pressure, dry cough, feeling short of breath;

• easy bruising, unusual bleeding, purple or red spots under your skin;

• thyroid symptoms--extreme tired feeling, dry skin, joint pain or stiffness, muscle pain or weakness, hoarse voice, feeling more sensitive to cold temperatures, weight gain;

• low white blood cell counts--fever, mouth sores, skin sores, sore throat, cough, trouble breathing; or

• low red blood cells (anemia)--pale skin, unusual tiredness, feeling light-headed or short of breath, cold hands and feet.

Common side effects of iobenguane I-131 may include:

• low blood cell counts;

• feeling tired;

• nausea, vomiting;

• dizziness; or

• low blood pressure (feeling light-headed).

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Some medicines can interfere with the quality of images produced by iobenguane I-131. Tell your doctor about all your current medicines and any you recently stopped using, especially:

• St. John's wort;

• tramadol;

• blood pressure medication;

• an antidepressant such as amitriptyline, bupropion, duloxetine, mirtazapine, venlafaxine, Wellbutrin, Cymbalta, Effexor, Pristiq, and others;

• diet pills, cold or cough medicine; or

• stimulant medicine such as dextroamphetamine, methylphenidate, Ritalin, Adderall, and others.

This list is not complete and many other drugs may affect iobenguane I-131. This includes prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible drug interactions are listed here.