New preparation of [123I]PE2I: investigation of the oxidation and purification steps

In order to simplify preparation of [123I]PE2I, iodogen and hydrogen peroxide were examined as oxidants for the preparation of radioiodinated PE2I, e.g. (E)‐N‐(3‐iodoprop‐2‐enyl)‐2β‐carbomethoxy‐3β‐(4′‐tolyl) nortropane). Among the oxidizing compounds assayed, iodogen appears to afford the best results for this purpose (high radiochemical yield, high chemical purity and a reasonable reaction time). A simplified and efficient method is described here for the preparation of [123I]PE2I based on the exchange of a 123I tributyl tin analogue in oxidative conditions followed by purification by solid phase extraction (SPE). Using this method, [123I]PE2I was obtained with a radio‐pharmaceutical yield over 60%, with chemical and radiochemical purities higher than 95% without the addition of a carrier (Na127I) (2G Bq/nmol) or with a specific activity adjusted to 85–90 MBq/nmol in the presence of the carrier.