Gamma scintigraphy in the delivery, biodistribution and targeting of therapeutic agents

The established clinical role of radionuclide imaging includes the diagnosis and monitoring of a wide range of clinical conditions. The therapeutic use of radionuclides has centred on a relatively small number of pathological conditions, particularly within the field of oncology. More recently there has been growing interest in the use of radionuclide imaging in drug evaluation and research (RIDER). Studies have been undertaken in order to increase the understanding of the in in vivo behaviour of pharmaceutical dosage forms in addition to the in vivo behaviour of molecular and cellular anti-tumour agents. The imaging facilities required for such undertakings are available in most nuclear medicine departments, although the expertise for radiolabelling and the requirements for the production of drug conjugates and pharmaceutical formulations are limited to a small number of centres. This paper discusses the application of radionuclide imaging in drug research with particular reference to the role of gamma-scintigraphy in monitoring the biodistribution and pharmacokinetics of immune mediated drug conjugates intended for the treatment of malignant disease. Examples described include the evaluation of oral and inhaled drug delivery systems and the biodistribution and in vivo kinetics of parenteral administrations.