An In Vitro Approach to Evaluate and Develop Potential 117mSn-based Bone-seeking Radiopharmaceuticals

Testing on animals has become standard practice for evaluating the potential efficacy of therapeutic or diagnostic agents. Not only are the overhead costs of such testing extremely high, but subjecting substantial numbers of animals to intensive testing and re-testing raises serious ethical questions and is widely unpopular with the public. This study explores the advantages of combining various analytical methods with mathematical and computer modeling to construct a multifaceted tool for the pre-vivo screening of prospective radiopharmaceuticals. The benefits of such a method lie in cost minimization and the avoidance of the ethical dimension. The 117mSn radionuclide was identified as an ideal pharmacological component for the treatment of bone pain, and two tin-bisphosponate complexes - Sn(II)-APDDMP and Sn(IV)-PEI-MP were chosen for evaluation. This book describes how these complexes were studied using various techniques including; glass electrode potentiometry, blood plasma modeling, observation of 31P spectra in time and tests for adsorption characteristics. Only one minimal biodistribution test in a rodent model proved necessary to confirm the predicted results. This method provides a holistic approach to investigating some of the fundamental issues in the development of radiopharmaceuticals. It allows for adaptation or the inclusion of additional techniques such as cell assays or dissociation kinetic measurements by free-ion selective radiotracer extraction (FISRE) as required, and makes it possible to better understand and predict the behavior of novel drug concepts without the use of costly and unpopular animal models.