Posted on December 2nd, 2008 by

Class: Radiopharmaceutical

Generic Name: Sodium Iodide (SOE-dee-um  EYE-oh-dyde) I 131
Trade Name: Iodotope®

How is this drug used? Sodium iodide I 131 is FDA approved for the treatment of some types of thyroid cancer. It is important for patients to remember that physicians have the ability to prescribe medication for conditions other than those for which the drug has been approved by the FDA. Patients who have received a prescription of this drug for a condition other than which it is approved may wish to discuss this issue with their physician.
What is the mechanism of action? Sodium iodide 131 belongs to a class of agents referred to as radiopharmaceuticals. Sodium iodide I 131 selectively collects in the thyroid, emitting radiation to kill the cancer cells and shrink the cancer.

How is sodium iodide I 131 given (administered)? Sodium iodide I 131 may be administered orally as a capsule, or as a solution, and the dose depends on several factors, including the condition being treated, the size of the patient, the particular regimen being used and the overall health of the patient. Patients may receive special instructions from their physician to get ready for treatment.

How are patients monitored? Patients will usually have scheduled meetings with their healthcare provider while they are being treated with sodium iodide I 131.  Typically, blood will be drawn to check levels of blood cells and to monitor functions of some organ systems, such as the kidneys or liver.  Patients may also undergo physical examinations, scans or other measures to assess side effects and response to therapy.

What are the most common (occur in 10 – 29% of patients) side effects of treatment with sodium iodide I 131?

• Low levels of white blood cells - increases risk of infection
• Low levels of red blood cells - increases risk of anemia
• Low levels of platelets - increases risk of bleeding
• Nausea and vomiting
• Increase in symptoms caused by the cancer
• Tenderness, swelling, pain of the neck
• Sore throat
• Cough
• Thinning of hair
• Allergic-type reactions
• Loss of taste (temporary)
• Tenderness of salivary glands

This is not a complete list of side effects. Some patients may experience other side effects that are not listed here. Patients may wish to discuss with their physician the other less common side effects of this drug, some of which may be serious.

Some side effects may require medical attention. Other side effects do not require medical attention and may go away during treatment. Patients should check with their physician about any side effects that continue or are bothersome.
What are the possible late side effects of treatment with sodium iodide I 131? Patients treated with sodium iodide I 131 are at an increased risk of developing a secondary malignancy.  A secondary malignancy is a new and unrelated cancer that occurs in an individual as a result of previous treatment with radiation or chemotherapy.  Patients should ask their physician about the possibility of developing a secondary malignancy as a result of their treatment.

What can patients do to help alleviate or prevent discomfort and side effects?

• Pay careful attention to the physician’s instructions and inform the physician of any side effects.
• Maintain adequate rest and nutrition.
• Wear sunscreen and protective clothing and try to minimize sun exposure.
• Drink plenty of fluids. (Patients should ask their physician about the amount of liquid to consume during a day.)
• Over the counter pain medication may help alleviate some pain caused by treatment. Patients should speak with their physician about this issue.
• Patients should prepare family members or roommates prior to treatment of the possible radiation precautions that need to be taken.
• If possible, the patient should avoid large crowds or persons who are sick or not feeling well, as this drug may leave some patients susceptible to infection.
• Wash hands often to reduce the risk of infection.
• Avoid activities that may cause injury or bruising.
• Use a soft toothbrush and an electric razor to prevent cuts on the mouth or skin.
• Eat small meals frequently to help alleviate nausea.

Are there any special precautions patients should be aware of before starting treatment?

• Patients should inform their physician if they are pregnant, breastfeeding or planning a family in the near future. This drug may cause birth defects. It is important to use some kind of birth control while undergoing treatment. Also, patients may want to talk to their physician if they are considering having children in the future, since some drugs may cause fertility problems.
• It is important that patients inform their physician of any pre-existing conditions (chicken pox, heart disease, kidney disease, liver disease, lung disease, etc.) as they may worsen with this drug.
• Patients should inform their physician of any other medication they are taking (whether prescription or over-the-counter, including vitamins, herbs, etc.) as they may interfere with treatment.
• Patients should check with their physician before starting any new drug or nutritional supplement.
• Patients should inform their physician of any known drug or food allergies or any reactions to medications they have experienced in the past.
• Patients are being treated with a radioactive substance, and radioactivity will be present in excreted urine. Patients need to discuss precautions against radioactivity with their physician and how long precautions should be followed.
• A toilet, versus a urinal should be used whenever possible. The toilet should be flushed several times immediately after every use. If urine spills outside the toilet, it should be cleaned up immediately and completely, and patients should wash their hands thoroughly. If blood or urine gets onto clothing, bed sheets, towels, etc., these items should be washed separately from other items.
• Patients should not use another persons eating or drinking utensils, towels or toothbrush.
• Wash eating utensils and clothes separately.
• Patients should not sit close to others, especially pregnant women.
• Patients should not engage in sex while being treated with sodium iodide I 131.
• If an oral dose is missed, do not double up on doses.  Patients should contact their doctor in this event.
• Keep tablets out of reach of children and return to the pharmacy for safe disposal if treatment is terminated.

When should patients notify their physician?

• Difficulty breathing
• Unusual bleeding (nosebleeds, bruising, pin sized red dots on skin, blood in urine or stool)
• Chest pain
• Swelling, pain, redness of one extremity and not the other
• Pain, lower back pain, side pain
• Swelling of feet or ankles
• Flu or cold-like symptoms - fever, chills, sore throat, cough, hoarseness
• Signs of infection – redness, swelling, pus, tenderness, painful or difficulty urination
• Severe fatigue

What is a package insert?
A package insert is required by the FDA and contains a summary of the essential scientific information needed for the safe and effective use of the drug for healthcare providers and consumers.  A package insert typically includes information regarding specific indications, administration schedules, dosing, side effects, contraindications, results from some clinical trials, chemical structure, pharmacokinetics and metabolism of the specific drug. By carefully reviewing the package insert, you will get the most complete and current information about how to safely use this drug. If you do not have the package insert for the drug you are using, your pharmacist or physician may be able to provide you with a copy.

Copyright © 2016 CancerConnect Last updated 07/10.

Important Limitations of Use

The information provided above on the drug you have selected is provided for your information only and is not a substitute for consultation with an appropriate medical doctor. We are providing this information solely as a courtesy and, as such, it is in no way a recommendation as to the safety, efficacy or appropriateness of any particular drug, regimen, dosing schedule for any particular cancer, condition or patient nor is it in any way to be considered medical advice. Patients should discuss the appropriateness of a particular drug or chemotherapy regimen with their physician.

As with any printed reference, the use of particular drugs, regimens and drug dosages may become out-of-date over time, since new information may have been published and become generally accepted after the latest update to this printed information. Please keep in mind that health care professionals are fully responsible for practicing within current standards, avoiding use of outdated regimens, employing good clinical judgment in selecting drugs and/or regimens, in calculating doses for individual patients, and verifying all dosage calculations.



The prescribing physician is solely responsible for making all decisions relating to appropriate patient care including, but not limited to, drugs, regimens, dose, schedule, and any supportive care.

Tags: I, Radiopharmaceutical

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