According to the FDA, written consent must be obtained to administer which drug?

Sodium Iodine 131 is a radiopharmaceutical that is used in the treatment of certain thyroid conditions, including hyperthyroidism and thyroid cancer. The reason written consent must be obtained prior to administering this drug is due to its radioactive properties and the potential risks associated with its use. These risks include radiation exposure to the patient and to others, as well as potential side effects that can arise from the medication.

In contrast, Technetium-99m is commonly used for diagnostic imaging and, because of its shorter half-life and lower associated risks, does not require similar consent protocols. Thallium-201, while also used for imaging, typically does not require written consent in the same way as Sodium Iodine 131 primarily because it is used in less risky protocols. Iodine-123 hardly requires written consent either, as it is often used in neurological imaging and presents a lower risk profile.

The requirement for written consent ensures that patients are fully informed about the nature of the treatment and any associated risks, which is essential in patient care, particularly for treatments involving radioactive materials.