A simple and efficient in vitro method for metabolism studies of radiotracers

In vitro metabolism of acetylcholinesterase inhibitors containing 3-[¹⁸F]fluoromethylbenzyl- ([¹⁸F]1) and 4-[¹⁸F]fluorobenzyl-piperidine moieties ([¹⁸F]2) was studied and compared with the in vivo metabolism. Defluorination of the [¹⁸F]1 mainly occurred to generate [¹⁸F]fluoride ion both in vitro and in vivo. In contrast, the [¹⁸F]2 was converted into an unknown polar metabolite in both metabolism methods and another metabolite, 4-[¹⁸F]fluorobenzoic acid in vitro. These results demonstrated that the in vitro method can be used to predict the in vivo metabolism of both radiotracers.