Scintigraphic Assessment of the Regional Distribution and Kinetics of Pharmaceuticals

Abstract

A lesser known use of imaging studies in drug development is to determine the patterns of deposition, biodistribution, and regional kinetics of drugs in the body. This kind of study is of most interest when the drug is intended for local action following topical administration by inhalation. Imaging provides a convenient noninvasive method for observing initial deposition patterns and their variations caused by variables of the drug’s formulation and delivery method. Though planar gamma imaging is the method that has most often been used, recent years have seen promising demonstrations of SPECT and PET imaging to provide three-dimensional and quantitative measurements of drug deposition. When the goal of a drug is direct local treatment of diseased tissue, delivery of that drug is an important therapeutic variable. Imaging studies allow the drug delivery to be measured and optimized before a drug formulation is committed to clinical trials.