Sodium iodide i 131 (Oral)

Sodium iodide I 131 is used to treat hyperthyroidism (an overactive thyroid) and certain types of thyroid cancer. This medicine is mainly taken up by the thyroid gland. In treating an overactive thyroid gland, the radiation from the radioactive iodine harms the thyroid gland to reduce its activity to normal levels. Larger doses of radioiodide are typically used after thyroid cancer surgery to destroy any remaining unhealthy thyroid tissue or to eliminate thyroid cancer that has spread to other areas.

When very small doses are given, measuring the radioactivity taken up by the gland helps your doctor determine if your thyroid gland is functioning properly or to find tumors caused by certain types of thyroid cancers.

This medicine should only be given by or under the direct supervision of a doctor who has specialized training in nuclear medicine or radiation oncology.

Your doctor will monitor your progress closely while you are taking this medicine. This helps your doctor see if the medicine is effective and decide if you should keep taking it. Blood and urine tests may be needed to check for side effects.

Using this medicine while pregnant can harm your unborn baby. If you are a woman who can get pregnant, your doctor may give you a pregnancy test before you start this medicine to ensure you are not pregnant. You must use two forms of birth control together for at least 6 months after using this medicine. Use birth control pills along with another form of birth control, like a condom, diaphragm, or contraceptive foam or jelly. If you think you have become pregnant while using the medicine, tell your doctor immediately.

If you are receiving sodium iodide I 131 for an overactive thyroid or thyroid cancer, your doctor may advise you to follow some or all of these guidelines for 48 to 96 hours after taking the medicine to help reduce the risk of contaminating others:

• Do not kiss anyone, or handle or use another person's eating or drinking utensils, toothbrush, or bathroom glass.
• Do not have sex.
• Do not sit close to others, especially pregnant women, and do not hold children in your lap for long periods.
• Sleep alone.
• Wash the tub and sink after each use (including after brushing your teeth).
• Wash your hands after using or cleaning the toilet.
• Use a separate towel and washcloth.
• Wash your clothes, bed linens, and eating utensils separately.
• Sodium iodide I 131 is passed in the urine. To prevent contamination of your home, flush the toilet twice after you urinate.

If you were treated with sodium iodide I 131 for an overactive thyroid, your doctor may want to check your thyroid hormone levels in your blood every 2 to 3 months during the first year, and then once a year thereafter. This is to ensure that your thyroid has not become underactive.

This medicine may cause allergic reactions. Contact your doctor immediately if you have a rash, hives, itching, fast heartbeat, shortness of breath, or swelling of the eyes, face, or lips after taking the medicine.

This medicine may increase your risk for cancer or thyroid issues. Discuss these risks with your doctor. You may need to take other medicines alongside this medicine to prevent thyroid problems.

You will be exposed to radiation risks while using this medicine. Speak with your doctor about these risks and any precautions you may need to take.

This medicine may cause temporary infertility in both men and women. Discuss this with your doctor if you plan to have children.

Do not take other medicines unless you have discussed them with your doctor. This includes prescription or over-the-counter medicines and herbal or vitamin supplements.

In deciding to use this medicine, it is important to consider the risks against the benefits. This is a choice you and your doctor will make together. For this medicine, the following points should be taken into account:

Allergies

Tell your doctor if you have ever had any unusual or allergic reactions to this medicine or any other medicines. Also inform your healthcare professional about any other allergies you may have, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.

Pediatric

There have not been enough studies to understand how sodium iodide I 131 capsules or solution affects children. Safety and effectiveness have not been established for this age group.

Geriatric

Current studies have not shown any specific problems in older adults that would limit the use of sodium iodide I 131 capsules or solution. However, older patients are more likely to have age-related kidney or heart issues, which may require caution and a dose adjustment for those receiving sodium iodide I 131 capsules or solution.

Breast Feeding

Studies in breastfeeding women have shown harmful effects on infants. You should be prescribed an alternative to this medication, or you should stop breastfeeding while taking this medicine.

Interactions with Medicines

Some medicines should never be used together, while others may be used together even if interactions could occur. In these cases, your doctor may adjust the dose or take other precautions. Inform your healthcare professional if you are taking any other prescription or nonprescription (over-the-counter [OTC]) medicine.

Interactions with Food/Tobacco/Alcohol

Some medicines should not be taken around the time of eating food or certain types of food due to possible interactions. Using alcohol or tobacco with some medicines may also cause interactions. Discuss with your healthcare professional about taking your medicine with food, alcohol, or tobacco.

Other Medical Problems

Having other medical issues may affect how you use this medicine. Be sure to tell your doctor if you have any other medical problems, especially:

• Asthma or
• Sulfite allergy, history of—This medicine contains sodium bisulfite, which can worsen these conditions.

• Diarrhea or vomiting or
• Thyroid cancer, medullary or anaplastic—Should not be used in patients with these conditions unless your doctor decides otherwise.

• Heart disease or
• Problems blocking the neck or throat (e.g., esophagus, trachea, or blood vessels in the neck)—Use with caution. May worsen these conditions.

• Kidney disease—Use with caution. The effects may be increased due to slower removal of the medicine from the body.

Along with its necessary effects, a medicine may cause some unwanted effects. Not all of these side effects may happen, but if they do, they may require medical attention.

Check with your doctor or nurse right away if any of the following side effects occur:

After treatment of overactive thyroid

Symptoms of an underactive thyroid

• Changes in menstrual periods
• Clumsiness
• Coldness
• Drowsiness
• Dry, puffy skin
• Headache
• Listlessness
• Muscle aches
• Thinning of the hair (temporary)
• Unusual tiredness or weakness
• Weight gain

Rare

After treatment of overactive thyroid

• Excessive sweating
• Fast, irregular, pounding, or racing heartbeat or pulse
• Fever
• Unusual irritability

After treatment of cancer of the thyroid

• Black, tarry stools
• Blood in the urine or stools
• Cough or hoarseness
• Fever or chills
• Lower back or side pain
• Painful or difficult swallowing
• Painful or difficult urination
• Pinpoint red spots on the skin
• Unusual bleeding or bruising

Incidence not known

After treatment of overactive thyroid

• Chest pain
• Fast, pounding, or irregular heartbeat or pulse
• Hives, itching, and rash
• Nervousness
• Sensitivity to heat
• Sweating
• Tenderness of salivary glands
• Trouble sleeping
• Weight loss

After treatment of cancer of the thyroid

• Abdominal or stomach cramps
• Bleeding gums
• Bone pain
• Diarrhea
• Feeling of discomfort
• Loss of appetite
• Nausea
• Sore throat
• Unusual tiredness or weakness
• Vomiting
• Weakness

Some 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. Your health care professional may also be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

Less common

After treatment of overactive thyroid or cancer of the thyroid

• Neck tenderness or swelling
• Sore throat

After treatment of cancer of the thyroid

• Loss of taste (temporary)
• Nausea and vomiting (temporary)
• Tenderness of the salivary glands

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

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

In the U.S.

• Iodotope

Available Dosage Forms:

• Kit

Therapeutic Class: Diagnostic Agent, Radiopharmaceutical Imaging

Before receiving this medicine, make sure you understand all the risks and benefits. It is important for you to work closely with your doctor during your treatment.

A nurse or other trained health professional will give you this medicine in a hospital or clinic. It is given by mouth.

Your doctor may have special instructions for you to get ready for your treatment. If you have not received such instructions or you do not understand them, check with your doctor ahead of time.