Which of the following factors can affect the radionuclidic purity of a radiopharmaceutical?

Radionuclidic purity refers to the proportion of the desired radionuclide in a radiopharmaceutical compared to other radionuclides present in the preparation. It is crucial for ensuring the safety and efficacy of the radiopharmaceutical for diagnostic or therapeutic applications.

Radiochemical impurities can significantly impact radionuclidic purity because they represent the presence of undesired radionuclides that may have been formed during the radiopharmaceutical production process or as a result of decay. The presence of these impurities can lead to inaccurate imaging results or unintended radiation exposure. Maintaining high radionuclidic purity is critical for achieving reliable diagnostic outcomes, as any added radionuclides could alter the biological behavior and distribution of the radiopharmaceutical in the body.

In this context, factors such as excessive heat, mode of excretion, and concentration of the active ingredient, while potentially influential in other aspects of radiopharmaceutical quality, do not directly address the presence of other radionuclides within the product. Therefore, radiochemical impurities stand out as a primary factor affecting radionuclidic purity.