Effect of the ProstheticGroup on the PharmacologicProperties of 18F-Labeled Rhodamine B, a PotentialMyocardial Perfusion Agent for Positron Emission Tomography (PET).

We recently reported the development of the 2-[18F]fluoroethylester of rhodamine B as a potential positron emission tomography (PET)tracer for myocardial perfusion imaging. This compound, which wasprepared using a [18F]fluoroethyl prosthetic group, hassignificant uptake in the myocardium in rats but also demonstratesrelatively high liver uptake and is rapidly hydrolyzed in vivo inmice. We have now prepared 18F-labeled rhodamine B usingthree additional prosthetic groups (propyl, diethylene glycol, andtriethylene glycol) and found that the prosthetic group has a significanteffect on the in vitro and in vivo properties of these compounds.Of the esters prepared to date, the diethylene glycol ester is superiorin terms of in vitro stability and pharmacokinetics. These observationssuggest that the prosthetic group plays a significant role in determiningthe pharmacological properties of 18F-labeled compounds.They also support the value of continued investigation of 18F-labeled rhodamines as PET radiopharmaceuticals for myocardial perfusionimaging. [ABSTRACT FROM AUTHOR]