FDA approves new dose of sodium fluoride for bone scans

After its withdrawal from the marketplace 35 years ago, sodium fluoride F 18 for use in bone scans is experiencing a rebirth as a result of a New Drug Application (NDA) submitted by the National Cancer Institute (NCI) and approved by FDA. The NDA, which changes the strength and maximum dose of sodium fluoride and approves its use in children, is the first ever filed by NCI or its parent organization, the National Institutes of Health.

The application also requires “good manufacturing practices” in the production of the drug.

The original sodium fluoride therapy was discontinued because of its higher price and shorter half-life - a mere 2 hours - and replaced by technetium-99m (Tc-99m) MDP, a less expensive radioactive tracer; however, the Tc-99m suffered problems of its own. The tracer is produced in nuclear reactors using highly enriched uranium; one reactor in Canada, which supplied most of the United States, has had frequent outages. In addition, the Tc-99m is used in Single Photon Emission Computed Tomography, while the sodium fluoride is produced in cyclotrons available in most hospitals and uses Position Emission Tomography, a more advanced imaging technique that provides earlier and more precise detection of bone metastases.

Paula Jacobs, acting associate director, Division of Cancer Treatment and Diagnosis, Cancer Imaging Program, NCI, hopes that the NDA will open the door to Abbreviated New Drug Applications for production of less expensive generic versions. “We expect that the NDA will increase the supply of sodium fluoride and make it more available to hospitals, as well as commercially,” she said, “and compensate for the continuing shortage of Tc-99m. It wasn’t a matter of safety or efficacy, but one of reliable supply.”

Jacobs anticipates that insurers will follow the lead of CMS, which allows Coverage With Evidence Development - allowing provisional access to sodium fluoride PET scans, while generating the evidence needed to determine whether unconditional coverage is warranted - in conjunction with a patient registry.