Sodium Iodide I 131 Capsules
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This article is compiled based on the United States Pharmacopeia (USP) – 2025 Edition
Issued and maintained by the United States Pharmacopeial Convention (USP)
Sodium iodide (Na131I).
Sodium iodide (Na131I) CAS RN®: 7790-26-3.
» Sodium Iodide I 131 Capsules contain radioactive iodine (131I) processed in the form of Sodium Iodide from products of uranium fission or the neutron bombardment of tellurium in such a manner that it is essentially carrier-free and contains only minute amounts of naturally occurring iodine 127. Capsules contain not less than 90.0 percent and not more than 110.0 percent of the labeled amount of 131I as iodide expressed in megabecquerels (microcuries or millicuries) at the time indicated in the labeling. Other chemical forms of radioactivity do not exceed 5 percent of the total radioactivity. The Capsules may contain a stabilizing agent.
Packaging and storage—Preserve in well-closed containers.
Labeling—Label the Capsules to include the following: the date of calibration; the amount of 131I as iodide expressed in megabecquerels (microcuries or millicuries) per Capsule at the time of calibration; a statement of whether the contents are intended for diagnostic or therapeutic use; the expiration date; and the statement “Caution—Radioactive Material.” The labeling indicates that in making dosage calculations, correction is to be made for radioactive decay, and also indicates that the radioactive half-life of 131I is 8.08 days.
Radionuclide identification—A solution or suspension of 1 or more Capsules in water responds to the test for Radionuclide identification under
Sodium Iodide I 131 Solution.
Uniformity of dosage units 〈905〉: meet the requirements.
Procedure for content uniformity—Determine the instrument response of each of 20 Capsules by measurement in a suitable counting assembly and under identical geometric conditions. Calculate the mean radioactivity value per Capsule. The requirements are met if not fewer than 19 of the Capsules are within the limits of 96.5% and 103.5% of the mean radioactivity value.
Radiochemical purity—Homogenize 1 Capsule in 3 mL of water, add 3 mL of methanol, and centrifuge. The supernatant meets the requirements of the test for Radiochemical purity under Sodium Iodide I 131 Solution.
Other requirements—A solution or suspension prepared by homogenizing 1 or more Capsules in sufficient water to yield a concentration of not less than 1 MBq (25 μCi) per mL meets the requirements of the Assay for radioactivity under Sodium Iodide I 131 Solution.
