Dendrimers in diagnostics

Dendrimers are currently under investigation as potential polymeric carrier s of contrast agents for magnetic resonance imaging (MRI), scintigraphy and X-ray techniques, i.e. computed tomography (CT). The objective for synthes izing large molecular weight contrast agents is to modify the pharmacokinet ic behavior of presently available small-sized compounds from a broad extra cellular to an intravascular distribution. Major target indications include angiography, tissue perfusion determination and tumor detection and differ entiation. In principle, imaging moieties, e.g. metal chelates for MRI and scintigraphy and triiodobenzene derivatives for CT,are coupled to a dendrim eric carrier characterized by a defined molecular weight. The structures an d sizes of these carriers are presently optimized. So far, however, no comp ound has reached the status of clinical application. Possible hurdles to ov ercome are synthetic problems such as drug uniformity, reproducible product ion of pure compounds and analytical issues, e.g. demonstrating purity. In principle, proof of concept for dendrimeric contrast agents as intravascula r and tumor-targeting substances seems to have been established. However, a lot of effort is still necessary before a dendrimeric contrast agent will finally be available for wide-spread use in patients.