Radioiodine dispensing and usage in a centralized hospital nuclear pharmacy

131I sodium iodide is the radiopharmaceutical of choice for both diagnosis and therapy in patients with various thyroid abnormalities. The radioiodide capsule has been the preferred dosage form, primarily because it provides a more convenient and safer vehicle for radioiodine administration. However, encapsulated 131I costs approximately twice as much a liquid 131I and does not provide as much flexibility as 131I solution in dosage selection. Also, the bioavailability of the capsular radioiodide preparation is inferior to that of the aqueous dosage form. The patient must swallow multiple capsules when a large amount of 131I activity is used. Capsule form is not suitable for any patient who has difficulty swallowing a capsule, has a feeding tube, or requires intravenous injection of 131I solution. In addition, radioiodide capsules must be analyzed statistically to ensure that the dosage units meet the United States Pharmacopeia uniformity requirements. If liquid radioiodine is used, distilled water rather than tap water should be used for dose preparation. It also is recommended that an antioxidant (e.g., sodium thiosulfate, sodium bisulfite), disodium edetate, and a pH adjustment of 7.5-9.0 be used to reduce radioiodide volatility. Due to the acceleration of the oxidative reaction caused by heat and light, 131I should be stored in a dark, cool environment. To comply with the quality management program implemented by the US Nuclear Regulatory Commission on January 27, 1992, all of the required information (e.g., prescribed dosage, procedure date, and signature of the authorized user) for a valid written directive is preprinted to ensure that the written directive is completed entirely and appropriately. Before each administration of therapeutic 131I solution, the calculated dose is verified by the prescribing physician, and the measured dose of 131I is reconfirmed by a second nuclear medicine technologist. Each patient's identity is verified by two methods (i.e., patient's full name and birth date).