SIDE EFFECTS: The side effects commonly seen with sodium iodide I 131 treatment are mild with the smaller doses given for hyperthyroidism but may be more severe with the larger doses given for thyroid cancer. Sodium iodide I 131 may cause suppression of the bone marrow, resulting in anemia, and reductions in white blood cells and platelets. It also may cause acute leukemia.
Other important side effects that can occur with large doses include symptoms of:
Thyroid crisis (due to the release of large amounts of thyroid hormone), severe inflammation of the salivary glands, and chromosomal abnormalities may occur. On day three after treatment, a constellation of signs and symptoms may occur including:
Finally, temporary hair thinning may occur two to three months after treatment.
GENERIC AVAILABLE: Yes
PREPARATIONS: Capsules; with radioactivity of 0.75 to 100 mCi per capsule. (A millicurie is a unit for measuring activity). Sodium iodide I 131also is available as a liquid in vials containing 5 to 150 mCi/vial.
STORAGE: Sodium iodide I 131 should be store at room temperature, 20-25 C (68-77 C). Sodium iodide I 131 is ordered for individual patients in a hospital setting. It arrives at room temperature in a lead container to minimize radiation exposure to hospital personnel. Special handling is required.
DOSING: The usual sodium iodide I 131 dose ranges from 4-10 mCi to treat hyperthyroidism. Doses to treat thyroid cancer are individualized and are usually 10-27 times greater than for hyperthyroidism.
DRUG INTERACTIONS: Non-radioactive iodine, thyroid hormone, propylthiouracil (PTU) or methimazole (Tapazole, Northyx) may all interfere with the trapping of sodium iodide I 131 by the thyroid gland. Thyroid hormone, drugs that contain iodine (for example, amiodarone [Coradone]), and iodine containing contrast agents all interfere with the action of sodium iodide I 131.
PREGNANCY: Sodium iodide I 131 has been shown to cause harm to a developing fetus. Use in pregnant women should be avoided.
NURSING MOTHERS: Iodine is excreted in breast milk. Therefore, formula feedings for infants are strongly recommended for nursing women requiring sodium iodide I 131 treatment.
Medically reviewed by Eni Williams, PharmD
Reference: FDA Prescribing Information
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