Loyola University Medical Education Network

Radiochemicals and Radiopharmaceuticals

There are many similarities between radiochemicals and radiopharmaceuticals. From the standpoint of both chemistry and radionuclide purity, there is usually minimal or no difference. The Tl-201 chloride sold as a radiochemical most likely came from the same cyclotron run as the radiopharmaceutical grade Tl-201 chloride used for diagnostic imaging.

Radiopharmaceuticals, however, have undergone a very lengthy and expensive regulatory process as well as extensive chemical and physical testing (pH, isotonicity, and chemical parameters) to insure that the final product is sterile, pyrogen-free, safe for human use, and is efficacious. This includes both animal and human studies prior to release of the product for sale.

Radiochemicals typically don't undergo this rigorous testing and neither their sterility nor apyrogenicity is guaranteed. Radiochemical usage is usually limited to chemical and biological research; in addition, the tracers used in RIA procedures are usually radiochemical grade. Radiopharmaceuticals are designed for diagnostic imaging and therapy procedures, but may also serve as tracers in research projects.


Stephen Karesh, PhD.

Last Updated: August 14, 1996
Created: March 1, 1996