Modelling DTPA therapy following Am contamination in rats

Area of Science:

• Radiochemistry
• Biokinetics
• Toxicology

Background:

• Standard biokinetic models are inadequate for actinide decorporation with DTPA due to perturbed radionuclide kinetics.
• Existing models are often empirical, limited to specific cases, and lack a unified structure for chelator interactions.

Purpose of the Study:

• To develop a generic biokinetic model for simultaneously describing americium (Am), DTPA, and the Am-DTPA chelate.
• To improve the assessment of radionuclide intake and dose estimation during decorporation therapy.

Main Methods:

• Utilized controlled animal studies with known Am contamination and varying DTPA administration (timing and dose).
• Proposed a model where DTPA chelates Am in both extracellular fluids and hepatocytes to enhance faecal excretion and reduce liver retention.
• Validated model predictions against experimental data for urinary/faecal excretion and liver accumulation.

Main Results:

• The proposed model demonstrated good agreement with experimental results for urinary and faecal excretion patterns.
• Model predictions accurately reflected reduced Am accumulation and retention in the liver.
• The model failed to satisfactorily reproduce Am decorporation from the skeletal compartment under the applied assumptions.

Conclusions:

• The developed generic model provides a framework for understanding Am biokinetics during DTPA decorporation, particularly concerning excretion and liver dynamics.
• Further refinement is needed to accurately model skeletal Am removal, suggesting limitations in the current assumptions regarding chelation sites or processes.