Recent developments in Tc-99(m)-labelled peptide-based radiopharmaceuticals: An overview

Nature has designed peptides to stimulate, inhibit or regulate many body fu nctions, The development of radiolabelled peptide-based radiopharmaceutical s for imaging a variety of tumours, infection/inflammation and thrombus has seen a new era in nuclear medicine. Recently, a number of Tc-99(m)-labelle d bioactive peptides have proven to be useful diagnostic imaging agents. Du e to their small size, peptide molecules exhibit favourable pharmacokinetic characteristics, such as rapid uptake by target tissue and rapid blood cle arance, which potentially allows images to be acquired earlier following th e administration of a Tc-99(m)-labelled peptide radiopharmaceutical. The ch allenge is to label bioactive peptides with Tc-99(m) with high specific act ivity without impairing the biological properties of the peptides. Molecula r engineering techniques now permit synthesis of a wide range of biological ly active peptides that carry chelating groups in their structure without a ffecting their receptor binding properties, thus permitting a high specific activity product. This review presents recent developments in Tc-99(m)-lab elled small peptides and their potential applications in the imaging of var ious types of diseases. In addition, the different techniques for radiolabe lling small bioactive peptides, the pharmacokinetic properties of peptides, and their potential as diagnostic imaging agents are also addressed. (C) 1 999 Lippincott Willlams & Wilkins).