Technetium-99m labelled integrated tropane–BAT as a potential dopamine transporter tracer Original Research Article

To reduce the molecular weight of 99mTc-labelled tropanes with the aim to enhance the passage over the blood–brain barrier, a so-called integrated tropane–BAT construct was developed. For this purpose a mercaptoethyl substituent was attached to the amine nitrogen atom of a nortropane precursor and the methyl carboxylate in 2β-position was converted to a 2-mercaptoethylaminomethylene substituent. This integrated tropane–BAT construct could be labelled efficiently (85–90%) with technetium-99m. Results of LC–MS analysis of the tracer agent support the assumed structure. Biodistribution studies in normal rats (n = 3) showed a slightly higher brain uptake for the new tracer agents as compared to 99mTc-TRODAT-1. These results indicate that further biological evaluation of the integrated 99mTc-tropane–BAT is warranted.