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1/29/2003

Oral Product Approved for Hyperthyroidism, Thyroid Cancer

Cheryl A. Thompson

A kit for preparing single-capsule doses of sodium iodide I-131, a radiopharmaceutical, for use in the treatment of hyperthyroidism and certain cases of thyroid cancer was recently approved for use in the United States.

The kit contains a highly concentrated solution of Sodium Iodide I-131 and two sizes of hard gelatin capsules.

According to the kit's labeling, a patient's dose is prepared by first diluting a portion of the solution so that the final liquid contains the quantity of radioactivity desired in a volume of 110 microliters or less. A nuclear pharmacist, nuclear pharmacy technician, or nuclear medicine physician places one of the small capsules from the kit in the bottom half of a large capsule, injects the diluted radiopharmaceutical solution into the unopened small capsule, and then closes the large capsule by affixing its top half. Until use, which should be within seven days of preparation, the finished capsule is to be stored in a polypropylene container in a lead pot.

The concentrated solution can also be used to prepare a dilution for use in patients unable to swallow a capsule.

Sodium iodide I-131, whether in a capsule or solution, must not be taken by patients who have been vomiting or have diarrhea. The radiopharmaceutical also must not be taken by women who are or may be pregnant.

After ingesting a dose of sodium iodide I-131, patients must take special precautions to minimize exposing other people to the radiation or contaminating the environment. The precautions are described in the kit's labeling (PDF). To ensure the rapid excretion of any radioiodide that is not absorbed by the thyroid, patients should also drink plenty of fluids before and after taking a dose.

DraxImage Inc. described its concentrated solution of sodium iodide I-131, containing 37 gigabecquerels per milliliter, as the first new formulation of the radiopharmaceutical in more than two decades.