Table of Contents
International Journal of Molecular Imaging
Volume 2011, Article ID 537687, 7 pages
http://dx.doi.org/10.1155/2011/537687
Review Article

Advances in Drug Design of Radiometal-Based Imaging Agents for Bone Disorders

1Division of Pharmaceutical Sciences, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
2Department of Patho-Functional Bioanalysis, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan

Received 5 August 2011; Accepted 26 September 2011

Academic Editor: Habib Zaidi

Copyright © 2011 Kazuma Ogawa and Hideo Saji. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Nuclear medicine bone imaging has been the optimum diagnosis for the detection of bone disorders because the lesion could be detectable before the appearance of symptomatic and radiographic changes. Over the past three decades, 99mTc-MDP and 99mTc-HMDP have been used as bone scintigraphic agents because of their superior biodistribution characteristics, although they are far from optimal from a chemical and pharmaceutical point of view. Recently, a more logical drug design has been proposed as a concept of bifunctional radiopharmaceuticals in which the carrier molecules (bisphosphonates) and radiometal chelating groups are separated within a molecule, specifically, 99mTc-mononuclear complex-conjugated bisphosphonate. Some of the 99mTc-mononuclear complex-conjugated bisphosphonate compounds showed superior biodistribution in preclinical studies. Moreover, the drug design concept could be applied to 68Ga PET bone imaging agents. These studies would provide useful information for the development of radiometal-based imaging and therapeutic agents for bone disorders such as bone metastases.