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Sodium Iodide I 131

Pronunciation: So-dee-uhm EYE-uh-dide I 131
Class: Radiopharmaceutical, Antithyroid agent

Trade Names

Sodium Iodide I 131
- Capsules 0.75 to 100 mCi
- Oral Solution 3.5 to 150 mCi

Pharmacology

After rapid GI absorption, iodine 131 is primarily distributed within extracellular fluid. It is trapped and rapidly converted to protein-bound iodine by the thyroid; it is concentrated, but not protein bound, by the stomach and salivary glands. It is promptly excreted by kidneys. About 90% of the local irradiation is caused by beta radiation and 10% is caused by gamma radiation. Iodine 131 has a physical half-life of 8.04 days.

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Indications and Usage

Thyroid carcinoma, hyperthyroidism.

Contraindications

Preexisting vomiting and diarrhea; women who are or may become pregnant.

Dosage and Administration

Thyroid Carcinoma, Hyperthyroidism
Adults

PO Individualize dosage. Usual dose for ablation of normal thyroid tissue: 50 mCi, with subsequent therapeutic doses usually 100 to 150 mCi.

General Advice

  • Dose will be prepared by a person authorized by the Nuclear Regulatory Commission and will be delivered ready to administer.
  • Administer prescribed dose via equipment supplied (eg, glass straw) and then return equipment to transport container for disposal.

Storage/Stability

Store in transport container until time of administration.

Drug Interactions

Iodine, thyroid, and antithyroid agents

Uptake of iodine 131 will be affected by recent intake of stable iodine in any form, or by use of thyroid, antithyroid, and certain other drugs.

Laboratory Test Interactions

None well documented.

Adverse Reactions

Endocrine

Acute thyroid crises.

Hematologic

Depression of hematopoietic system with large doses; bone marrow depression; acute leukemia; anemia; blood dyscrasia; leukopenia; thrombocytopenia; death.

Miscellaneous

Radiation sickness; severe sialoadenitis; increased clinical symptoms; chest pain; tachycardia; rash; hives; chromosomal abnormalities; tenderness and swelling of neck; pain on swallowing; sore throat and cough may occur around third day after treatment; temporary hair thinning (may occur 2 to 3 mo after treatment).

Precautions

Pregnancy

Category X .

Lactation

Discontinue breast-feeding during therapy. Do not resume breast-feeding until all radiation is absent from breast milk (approximately 14 days).

Children

Safety and efficacy have not been established.

Sulfite Sensitivity

Contains sulfites that may cause allergic-type reactions, including anaphylactic symptoms.

Radiation exposure

Ensure minimum radiation exposure to patients and occupational workers consistent with proper patient management.

Overdosage

Symptoms

Hypothyroidism.

Patient Information

  • Advise patient that medication will be prepared and administered by health care provider in a health care setting.
  • Advise patient, family, or caregiver that medication is usually administered 1 time only.
  • Advise patient, family, or caregiver to report any of the following to the health care provider: persistent or worsening tenderness or swelling of the neck; pain on swallowing; sore throat; cough; persistent nausea or vomiting; worsening symptoms of hyperthyroidism; any other unexplained sensation.

Copyright © 2009 Wolters Kluwer Health.

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