Pipeline Impact of Radiolabeled Compounds in Drug Discovery and Development.

The long-lived radionuclides tritium and carbon-14 have been used for many years in pharmaceutical research and development for making key efficacy and toxicological decisions. Early discovery utilizes radiolabels for compound selection through radioligand binding assays and autoradiography. In preclinical safety evaluation, the use of labeled compounds for adsorption, distribution, metabolism, and excretion studies is often preferred for the added detection sensitivity. As the drug substance proceeds to the clinic, human metabolism studies are reliant on the use of labeled materials to fulfill required regulatory applications.