Indications and Usage

  • This drug is useful to decrease the thyroid's retention of radioiodine and may be considered if it is too late for KI (potassium iodide) to be effective.
  • Suggested PO dosing
    • 100 mg (2 tabs, 50 mg/tab) PO tid
    • Can be given daily for 8 days.

FDA Product Safety Info

  • Not FDA approved for this indication/off-label use
  • When KI is unavailable or contraindicated, propylthiouracil and methimazole may be considered alternative drugs for blocking thyroid uptake of radioiodine. However, propylthiouracil is not FDA-approved as a substitute for KI, and it should be used only in the case of documented and serious internal contamination with radioiodine when KI is unavailable or unlikely to be effective.
  • Propylthiouracil should not be used unless a health physicist has documented the expected thyroid radiation dose.
  • For adults over 40 years of age, treatment for radioiodine inhalation is not recommended unless the projected thyroid dose exceeds 500 rem.
  • The potential for granulocytopenia and agranulocytosis is significant.
  • WARNING: Pregnancy Category D

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Drug Label

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  1. Management of Persons Contaminated with Radionuclides: Handbook (NCRP Report No. 161, Vol. I), National Council on Radiation Protection and Measurements, Bethesda, MD, 2008, Medical Treatments Arranged by Radionuclide (p. 215) and Table 12.15 (pp. 216-217). [Note: NCRP 161 supersedes NCRP 65.]