Pharmaceutical factors that may affect diagnostic and therapeutic outcomes of thyroid disorders
Abstract
Radioactive sodium iodide is the drug of choice for therapy and diagnosis in patients with thyroid disorders. Assurance of the bioavailability of the radioiodide for uptake by the thyroid is essential to obtaining the desired outcome. Variability in the bioavailability of radioiodide between dosage forms could affect the outcome of either a diagnostic study or therapeutic application of the radiopharmaceutical. Also, the presence of an interfering agent in the patient may adversely affect applications of radioiodide for the thyroid. Therefore, a clear understanding of pharmaceutical factors that may affect the outcome of the diagnosis and the treatment of thyroid disorders is most important. Euthyroid rats were employed to determine the influence of several agents on the percentage uptake of radioiodide by the thyroid. The objective of the investigation was to study the influence of agent and the dose of the agent on the uptake of radioiodide as well as the length of interference. Potassium iodide, propylthiouracil, diatrizoate meglumine and iohexol were selected for the study. Two doses of each agent were investigated. Radioiodide thyroid uptake was determined at 1, 8, 15, and 22 days following administration of the agents. The percentage radioiodide uptake value for the thyroid decreased significantly compared to controls for all agents and both doses on day one. The percentage radioiodide uptake values returned to normal control levels at day 22 for all agents and both doses. The relationship between radioiodide thyroid uptake values in hyperthyroid cats and in vitro dissolution profiles for capsules prepared with two formulations was studied. Radioiodide thyroid uptake data at 24 hours after administration did not vary significantly between a formulation that exhibited good release characteristic in vitro and a formulation that released the radioactive iodide more slowly and to a lesser extent. In vitro dissolution profiles for capsules prepared with different volumes of radioactive sodium iodide solution and stored for various times were determined. It was found that none of these factors exhibited a significance influence on the in vitro dissolution profiles.
Degree
Ph.D.
Advisors
Shaw, Purdue University.
Subject Area
Pharmaceuticals|Surgery|Pharmacology
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